diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 135e5b5f..488b9032 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -382,13 +382,6 @@ Security/YAMLLoad:
     - 'lib/stack_master/parameter_loader.rb'
     - 'lib/stack_master/template_utils.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: prefer_alias, prefer_alias_method
-Style/Alias:
-  Exclude:
-    - 'lib/stack_master/sparkle_formation/template_file.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: always, conditionals
@@ -396,50 +389,6 @@ Style/AndOr:
   Exclude:
     - 'lib/stack_master/cli.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, ProceduralMethods, FunctionalMethods, AllowedMethods, AllowedPatterns, AllowBracesOnProceduralOneLiners, BracesRequiredMethods.
-# SupportedStyles: line_count_based, semantic, braces_for_chaining, always_braces
-# ProceduralMethods: benchmark, bm, bmbm, create, each_with_object, measure, new, realtime, tap, with_object
-# FunctionalMethods: let, let!, subject, watch
-# AllowedMethods: lambda, proc, it
-Style/BlockDelimiters:
-  Exclude:
-    - 'lib/stack_master/aws_driver/s3.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample-ctp.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample.rb'
-    - 'spec/stack_master/change_set_spec.rb'
-    - 'spec/stack_master/command_spec.rb'
-    - 'spec/stack_master/commands/compile_spec.rb'
-    - 'spec/stack_master/commands/drift_spec.rb'
-    - 'spec/stack_master/commands/lint_spec.rb'
-    - 'spec/stack_master/commands/nag_spec.rb'
-    - 'spec/stack_master/config_spec.rb'
-    - 'spec/stack_master/paged_response_accumulator_spec.rb'
-    - 'spec/stack_master/parameter_resolver_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/one_password_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/sns_topic_name_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/sso_group_id_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/stack_output_spec.rb'
-    - 'spec/stack_master/security_group_finder_spec.rb'
-    - 'spec/stack_master/sparkle_formation/template_file_spec.rb'
-    - 'spec/stack_master/stack_differ_spec.rb'
-    - 'spec/stack_master/stack_events/fetcher_spec.rb'
-    - 'spec/stack_master/stack_events/streamer_spec.rb'
-    - 'spec/stack_master/stack_spec.rb'
-    - 'spec/stack_master/template_compiler_spec.rb'
-    - 'spec/stack_master/template_compilers/json_spec.rb'
-    - 'spec/stack_master/template_compilers/sparkle_formation_spec.rb'
-    - 'spec/stack_master/template_compilers/yaml_spec.rb'
-    - 'spec/stack_master/test_driver/cloud_formation_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowOnConstant, AllowOnSelfClass.
-Style/CaseEquality:
-  Exclude:
-    - 'lib/stack_master/parameter_resolver.rb'
-    - 'lib/stack_master/stack_definition.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle, EnforcedStyleForClasses, EnforcedStyleForModules.
 # SupportedStyles: nested, compact
@@ -453,21 +402,6 @@ Style/ClassAndModuleChildren:
     - 'lib/stack_master/template_compilers/yaml.rb'
     - 'lib/stack_master/template_compilers/yaml_erb.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, AllowInnerBackticks.
-# SupportedStyles: backticks, percent_x, mixed
-Style/CommandLiteral:
-  Exclude:
-    - 'lib/stack_master/parameter_resolvers/one_password.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, SingleLineConditionsOnly, IncludeTernaryExpressions.
-# SupportedStyles: assign_to_condition, assign_inside_condition
-Style/ConditionalAssignment:
-  Exclude:
-    - 'lib/stack_master/command.rb'
-    - 'lib/stack_master/parameter_validator.rb'
-
 # Configuration parameters: AllowedConstants.
 Style/Documentation:
   Exclude:
@@ -557,46 +491,6 @@ Style/Documentation:
     - 'lib/stack_master/utils.rb'
     - 'lib/stack_master/validator.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/EachWithObject:
-  Exclude:
-    - 'features/step_definitions/stack_steps.rb'
-    - 'lib/stack_master/config.rb'
-    - 'lib/stack_master/parameter_loader.rb'
-    - 'lib/stack_master/parameter_resolver.rb'
-    - 'lib/stack_master/stack.rb'
-    - 'lib/stack_master/stack_definition.rb'
-    - 'lib/stack_master/utils.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/EmptyLiteral:
-  Exclude:
-    - 'lib/stack_master/test_driver/s3.rb'
-    - 'spec/stack_master/stack_differ_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: compact, expanded
-Style/EmptyMethod:
-  Exclude:
-    - 'lib/stack_master/test_driver/s3.rb'
-    - 'spec/stack_master/parameter_resolver_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/Encoding:
-  Exclude:
-    - 'stack_master.gemspec'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/ExpandPathArguments:
-  Exclude:
-    - 'stack_master.gemspec'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/ExplicitBlockArgument:
-  Exclude:
-    - 'lib/stack_master/parameter_resolver.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: always, always_true, never
@@ -609,44 +503,10 @@ Style/GlobalStdStream:
     - 'lib/stack_master/cli.rb'
     - 'spec/stack_master/commands/apply_spec.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: MinBodyLength, AllowConsecutiveConditionals.
-Style/GuardClause:
-  Exclude:
-    - 'lib/stack_master/aws_driver/cloud_formation.rb'
-    - 'lib/stack_master/commands/apply.rb'
-    - 'lib/stack_master/commands/events.rb'
-    - 'lib/stack_master/commands/init.rb'
-    - 'lib/stack_master/parameter_resolver.rb'
-    - 'lib/stack_master/parameter_resolvers/ejson.rb'
-    - 'lib/stack_master/parameter_resolvers/stack_output.rb'
-    - 'lib/stack_master/sparkle_formation/compile_time/value_builder.rb'
-    - 'lib/stack_master/test_driver/cloud_formation.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, EnforcedShorthandSyntax, UseHashRocketsWithSymbolValues, PreferHashRocketsForNonAlnumEndingSymbols.
-# SupportedStyles: ruby19, hash_rockets, no_mixed_keys, ruby19_no_mixed_keys
-# SupportedShorthandSyntax: always, never, either, consistent, either_consistent
-Style/HashSyntax:
-  Exclude:
-    - 'Rakefile'
-    - 'lib/stack_master/template_compilers/sparkle_formation.rb'
-    - 'spec/stack_master/aws_driver/s3_spec.rb'
-    - 'spec/stack_master/commands/delete_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/latest_container_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/stack_output_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/IfUnlessModifier:
+# This cop supports unsafe autocorrection (--autocorrect-all).
+Style/HashTransformValues:
   Exclude:
-    - 'bin/stack_master'
-    - 'lib/stack_master/change_set.rb'
-    - 'lib/stack_master/commands/apply.rb'
-    - 'lib/stack_master/commands/drift.rb'
-    - 'lib/stack_master/commands/events.rb'
-    - 'lib/stack_master/sparkle_formation/compile_time/value_builder.rb'
-    - 'lib/stack_master/sparkle_formation/compile_time/value_validator.rb'
-    - 'lib/stack_master/stack_differ.rb'
+    - 'lib/stack_master/stack.rb'
 
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: InverseMethods, InverseBlocks.
@@ -654,26 +514,6 @@ Style/InverseMethods:
   Exclude:
     - 'lib/stack_master/commands/tidy.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/KeywordParametersOrder:
-  Exclude:
-    - 'lib/stack_master/diff.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowedMethods, AllowedPatterns.
-Style/MethodCallWithoutArgsParentheses:
-  Exclude:
-    - 'lib/stack_master/commands/tidy.rb'
-    - 'lib/stack_master/parameter_resolvers/sso_group_id.rb'
-    - 'spec/stack_master/commands/init_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: require_parentheses, require_no_parentheses, require_no_parentheses_except_multiline
-Style/MethodDefParentheses:
-  Exclude:
-    - 'lib/stack_master/config.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle, Autocorrect.
 # SupportedStyles: module_function, extend_self, forbidden
@@ -684,11 +524,6 @@ Style/ModuleFunction:
     - 'lib/stack_master/template_utils.rb'
     - 'lib/stack_master/utils.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/MultilineIfModifier:
-  Exclude:
-    - 'lib/stack_master/cli.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: literals, strict
@@ -701,33 +536,6 @@ Style/MutableConstant:
     - 'lib/stack_master/sparkle_formation/compile_time/value_validator_factory.rb'
     - 'lib/stack_master/version.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: both, prefix, postfix
-Style/NegatedIf:
-  Exclude:
-    - 'lib/stack_master/commands/init.rb'
-    - 'lib/stack_master/commands/tidy.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, MinBodyLength, AllowConsecutiveConditionals.
-# SupportedStyles: skip_modifier_ifs, always
-Style/Next:
-  Exclude:
-    - 'lib/stack_master/commands/tidy.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: MinDigits, Strict, AllowedNumbers, AllowedPatterns.
-Style/NumericLiterals:
-  Exclude:
-    - 'lib/stack_master/template_compilers/json.rb'
-    - 'lib/stack_master/template_utils.rb'
-    - 'spec/stack_master/commands/apply_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/latest_ami_spec.rb'
-    - 'spec/stack_master/stack_spec.rb'
-    - 'spec/stack_master/template_compilers/json_spec.rb'
-    - 'spec/stack_master/template_utils_spec.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle, AllowedMethods, AllowedPatterns.
 # SupportedStyles: predicate, comparison
@@ -745,18 +553,6 @@ Style/OptionalBooleanParameter:
     - 'lib/stack_master/commands/status.rb'
     - 'lib/stack_master/stack.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/ParallelAssignment:
-  Exclude:
-    - 'lib/stack_master/cli.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: PreferredDelimiters.
-Style/PercentLiteralDelimiters:
-  Exclude:
-    - 'spec/stack_master/identity_spec.rb'
-    - 'stack_master.gemspec'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle, AllowedCompactTypes.
 # SupportedStyles: compact, exploded
@@ -769,17 +565,6 @@ Style/RaiseArgs:
     - 'lib/stack_master/sparkle_formation/compile_time/parameters_validator.rb'
     - 'lib/stack_master/template_compilers/sparkle_formation.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantAssignment:
-  Exclude:
-    - 'lib/stack_master/commands/tidy.rb'
-    - 'lib/stack_master/parameter_resolvers/ami_finder.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantException:
-  Exclude:
-    - 'spec/stack_master/command_spec.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Style/RedundantInterpolation:
   Exclude:
@@ -788,50 +573,6 @@ Style/RedundantInterpolation:
     - 'lib/stack_master/stack_definition.rb'
     - 'spec/stack_master/stack_definition_spec.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantPercentQ:
-  Exclude:
-    - 'stack_master.gemspec'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantRegexpCharacterClass:
-  Exclude:
-    - 'spec/stack_master/command_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantRegexpEscape:
-  Exclude:
-    - 'spec/stack_master/stack_differ_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowMultipleReturnValues.
-Style/RedundantReturn:
-  Exclude:
-    - 'lib/stack_master/parameter_resolvers/one_password.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantSelf:
-  Exclude:
-    - 'lib/stack_master/commands/list_stacks.rb'
-    - 'lib/stack_master/commands/outputs.rb'
-    - 'lib/stack_master/commands/status.rb'
-    - 'lib/stack_master/resolver_array.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, AllowInnerSlashes.
-# SupportedStyles: slashes, percent_r, mixed
-Style/RegexpLiteral:
-  Exclude:
-    - 'lib/stack_master/commands/terminal_helper.rb'
-    - 'lib/stack_master/sparkle_formation/compile_time/allowed_pattern_validator.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: implicit, explicit
-Style/RescueStandardError:
-  Exclude:
-    - 'spec/stack_master/command_spec.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: ConvertCodeThatCanStartToReturnNil, AllowedMethods, MaxChainLength.
 # AllowedMethods: present?, blank?, presence, try, try!
@@ -843,13 +584,6 @@ Style/SafeNavigation:
     - 'lib/stack_master/stack_status.rb'
     - 'lib/stack_master/template_compilers/sparkle_formation.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: only_raise, only_fail, semantic
-Style/SignalException:
-  Exclude:
-    - 'lib/stack_master/resolver_array.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: RequireEnglish, EnforcedStyle.
 # SupportedStyles: use_perl_names, use_english_names, use_builtin_english_names
@@ -868,98 +602,6 @@ Style/StringConcatenation:
     - 'spec/stack_master/commands/compile_spec.rb'
     - 'spec/stack_master/template_utils_spec.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, ConsistentQuotesInMultiline.
-# SupportedStyles: single_quotes, double_quotes
-Style/StringLiterals:
-  Exclude:
-    - 'Rakefile'
-    - 'bin/stack_master'
-    - 'example/simple/templates/myapp_vpc.rb'
-    - 'example/simple/templates/myapp_web.rb'
-    - 'features/step_definitions/parameter_store_steps.rb'
-    - 'features/support/env.rb'
-    - 'lib/stack_master.rb'
-    - 'lib/stack_master/aws_driver/s3.rb'
-    - 'lib/stack_master/change_set.rb'
-    - 'lib/stack_master/cli.rb'
-    - 'lib/stack_master/commands/apply.rb'
-    - 'lib/stack_master/commands/delete.rb'
-    - 'lib/stack_master/commands/drift.rb'
-    - 'lib/stack_master/commands/init.rb'
-    - 'lib/stack_master/commands/lint.rb'
-    - 'lib/stack_master/commands/status.rb'
-    - 'lib/stack_master/commands/terminal_helper.rb'
-    - 'lib/stack_master/commands/tidy.rb'
-    - 'lib/stack_master/config.rb'
-    - 'lib/stack_master/diff.rb'
-    - 'lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb'
-    - 'lib/stack_master/parameter_resolvers/latest_container.rb'
-    - 'lib/stack_master/parameter_resolvers/one_password.rb'
-    - 'lib/stack_master/prompter.rb'
-    - 'lib/stack_master/role_assumer.rb'
-    - 'lib/stack_master/security_group_finder.rb'
-    - 'lib/stack_master/sns_topic_finder.rb'
-    - 'lib/stack_master/stack_definition.rb'
-    - 'lib/stack_master/stack_differ.rb'
-    - 'lib/stack_master/validator.rb'
-    - 'lib/stack_master/version.rb'
-    - 'spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/dynamics/my_dynamic.rb'
-    - 'spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates/dynamics/local_dynamic.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample-ctp.rb'
-    - 'spec/fixtures/templates/rb/cfndsl/sample.rb'
-    - 'spec/fixtures/templates/rb/sparkle_formation/templates/template.rb'
-    - 'spec/integration/drift_spec.rb'
-    - 'spec/spec_helper.rb'
-    - 'spec/stack_master/aws_driver/s3_spec.rb'
-    - 'spec/stack_master/commands/apply_spec.rb'
-    - 'spec/stack_master/commands/compile_spec.rb'
-    - 'spec/stack_master/commands/delete_spec.rb'
-    - 'spec/stack_master/commands/drift_spec.rb'
-    - 'spec/stack_master/commands/init_spec.rb'
-    - 'spec/stack_master/commands/lint_spec.rb'
-    - 'spec/stack_master/commands/nag_spec.rb'
-    - 'spec/stack_master/commands/status_spec.rb'
-    - 'spec/stack_master/commands/validate_spec.rb'
-    - 'spec/stack_master/config_spec.rb'
-    - 'spec/stack_master/parameter_loader_spec.rb'
-    - 'spec/stack_master/parameter_resolver_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/ami_finder_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/ejson_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/latest_container_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/one_password_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/parameter_store_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/security_group_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/security_groups_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/stack_output_spec.rb'
-    - 'spec/stack_master/parameter_validator_spec.rb'
-    - 'spec/stack_master/security_group_finder_spec.rb'
-    - 'spec/stack_master/sparkle_formation/template_file_spec.rb'
-    - 'spec/stack_master/sso_group_id_finder_spec.rb'
-    - 'spec/stack_master/stack_definition_spec.rb'
-    - 'spec/stack_master/stack_differ_spec.rb'
-    - 'spec/stack_master/stack_events/presenter_spec.rb'
-    - 'spec/stack_master/stack_events/streamer_spec.rb'
-    - 'spec/stack_master/stack_spec.rb'
-    - 'spec/stack_master/template_compiler_spec.rb'
-    - 'spec/stack_master/template_compilers/cfndsl_spec.rb'
-    - 'spec/stack_master/template_compilers/json_spec.rb'
-    - 'spec/stack_master/template_compilers/sparkle_formation_spec.rb'
-    - 'spec/stack_master/template_utils_spec.rb'
-    - 'spec/stack_master/test_driver/cloud_formation_spec.rb'
-    - 'spec/stack_master/utils_spec.rb'
-    - 'spec/stack_master/validator_spec.rb'
-    - 'spec/stack_master_spec.rb'
-    - 'spec/support/aws_stubs.rb'
-    - 'stack_master.gemspec'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: MinSize.
-# SupportedStyles: percent, brackets
-Style/SymbolArray:
-  EnforcedStyle: brackets
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: AllowMethodsWithArguments, AllowedMethods, AllowedPatterns, AllowComments.
 # AllowedMethods: define_method
@@ -968,57 +610,6 @@ Style/SymbolProc:
     - 'lib/stack_master/command.rb'
     - 'spec/support/validator_spec.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyleForMultiline.
-# SupportedStylesForMultiline: comma, consistent_comma, diff_comma, no_comma
-Style/TrailingCommaInArguments:
-  Exclude:
-    - 'lib/stack_master/template_compilers/sparkle_formation.rb'
-    - 'spec/stack_master/validator_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyleForMultiline.
-# SupportedStylesForMultiline: comma, consistent_comma, diff_comma, no_comma
-Style/TrailingCommaInArrayLiteral:
-  Exclude:
-    - 'lib/stack_master/security_group_finder.rb'
-    - 'spec/integration/drift_spec.rb'
-    - 'spec/stack_master/cloudformation_interpolating_eruby_spec.rb'
-    - 'spec/stack_master/parameter_resolvers/latest_container_spec.rb'
-    - 'spec/stack_master/security_group_finder_spec.rb'
-    - 'spec/stack_master/sns_topic_finder_spec.rb'
-    - 'spec/stack_master/stack_definition_spec.rb'
-    - 'spec/stack_master/stack_events/fetcher_spec.rb'
-    - 'spec/stack_master/stack_events/streamer_spec.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyleForMultiline.
-# SupportedStylesForMultiline: comma, consistent_comma, diff_comma, no_comma
-Style/TrailingCommaInHashLiteral:
-  Exclude:
-    - 'lib/stack_master/commands/status.rb'
-    - 'lib/stack_master/config.rb'
-    - 'lib/stack_master/parameter_resolvers/latest_container.rb'
-    - 'lib/stack_master/security_group_finder.rb'
-    - 'lib/stack_master/sso_group_id_finder.rb'
-    - 'spec/integration/drift_spec.rb'
-    - 'spec/stack_master/commands/apply_spec.rb'
-    - 'spec/stack_master/config_spec.rb'
-    - 'spec/stack_master/security_group_finder_spec.rb'
-    - 'stack_master.gemspec'
-
-# This cop supports safe autocorrection (--autocorrect).
-Style/UnlessElse:
-  Exclude:
-    - 'lib/stack_master/cli.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: WordRegex.
-# SupportedStyles: percent, brackets
-Style/WordArray:
-  EnforcedStyle: percent
-  MinSize: 4
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Style/ZeroLengthPredicate:
   Exclude:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index da098b86..110c2e67 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,12 @@ The format is based on [Keep a Changelog], and this project adheres to
 
 ## [Unreleased]
 
+### Changed
+
+- Resolve style issues identified by RuboCop ([#396])
+
 [Unreleased]: https://github.com/envato/stack_master/compare/v2.17.1...HEAD
+[#396]: https://github.com/envato/stack_master/pull/396
 
 ## [2.17.1] - 2025-12-19
 
diff --git a/Rakefile b/Rakefile
index 161a82dd..ced81b38 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,11 +1,11 @@
-require "bundler/gem_tasks"
+require 'bundler/gem_tasks'
 require 'bundler/setup'
 
 task :environment do
   require 'stack_master'
 end
 
-task :console => :environment do
+task console: :environment do
   require 'pry'
   binding.pry
 end
@@ -19,7 +19,7 @@ begin
 
   require 'rspec/core/rake_task'
   RSpec::Core::RakeTask.new(:spec) do |t|
-    t.rspec_opts = "--format doc"
+    t.rspec_opts = '--format doc'
   end
 
   require 'rubocop/rake_task'
@@ -27,4 +27,4 @@ begin
 rescue LoadError
 end
 
-task :default => [:features, :spec, :rubocop]
+task default: %i[features spec rubocop]
diff --git a/bin/stack_master b/bin/stack_master
index 5379c577..09e8f56e 100755
--- a/bin/stack_master
+++ b/bin/stack_master
@@ -2,14 +2,12 @@
 
 require 'stack_master'
 
-if ENV['STUB_AWS'] == 'true'
-  require 'stack_master/testing'
-end
+require 'stack_master/testing' if ENV['STUB_AWS'] == 'true'
 
-trap("SIGINT") { raise StackMaster::CtrlC }
+trap('SIGINT') { raise StackMaster::CtrlC }
 
 begin
   StackMaster::CLI.new(ARGV.dup).execute!
 rescue StackMaster::CtrlC
-  StackMaster.stdout.puts "Exiting..."
+  StackMaster.stdout.puts 'Exiting...'
 end
diff --git a/example/simple/templates/myapp_vpc.rb b/example/simple/templates/myapp_vpc.rb
index e26bf84c..b18e38ca 100644
--- a/example/simple/templates/myapp_vpc.rb
+++ b/example/simple/templates/myapp_vpc.rb
@@ -1,5 +1,5 @@
 SparkleFormation.new(:myapp_vpc) do
-  description "A test VPC template"
+  description 'A test VPC template'
 
   resources.vpc do
     type 'AWS::EC2::VPC'
diff --git a/example/simple/templates/myapp_web.rb b/example/simple/templates/myapp_web.rb
index 638f6a33..39b7cccb 100644
--- a/example/simple/templates/myapp_web.rb
+++ b/example/simple/templates/myapp_web.rb
@@ -1,5 +1,5 @@
 SparkleFormation.new(:myapp_web) do
-  description "Test web template"
+  description 'Test web template'
 
   parameters.vpc_id do
     description 'VPC ID'
diff --git a/features/step_definitions/parameter_store_steps.rb b/features/step_definitions/parameter_store_steps.rb
index 1afc9224..384ca190 100644
--- a/features/step_definitions/parameter_store_steps.rb
+++ b/features/step_definitions/parameter_store_steps.rb
@@ -6,7 +6,7 @@
         parameter: {
           name: parameter_name,
           value: parameter_value,
-          type: "SecureString",
+          type: 'SecureString',
           version: 1
         }
       }
diff --git a/features/step_definitions/stack_steps.rb b/features/step_definitions/stack_steps.rb
index 7b535eb3..44ca2902 100644
--- a/features/step_definitions/stack_steps.rb
+++ b/features/step_definitions/stack_steps.rb
@@ -21,10 +21,9 @@
 end
 
 def extract_hash_from_kv_string(string)
-  string.to_s.split(',').inject({}) do |hash, kv|
+  string.to_s.split(',').each_with_object({}) do |kv, hash|
     key, value = kv.split('=')
     hash[key] = value
-    hash
   end
 end
 
@@ -32,9 +31,8 @@ def extract_hash_from_kv_string(string)
   table.hashes.each do |row|
     row.symbolize_keys!
     row[:parameters] = StackMaster::Utils.hash_to_aws_parameters(extract_hash_from_kv_string(row[:parameters]))
-    outputs = extract_hash_from_kv_string(row[:outputs]).inject([]) do |array, (k, v)|
+    outputs = extract_hash_from_kv_string(row[:outputs]).each_with_object([]) do |(k, v), array|
       array << OpenStruct.new(output_key: k, output_value: v)
-      array
     end
     row[:outputs] = outputs
     StackMaster.cloud_formation_driver.add_stack(row)
diff --git a/features/support/env.rb b/features/support/env.rb
index 7e3ca482..a9723a65 100644
--- a/features/support/env.rb
+++ b/features/support/env.rb
@@ -22,5 +22,5 @@
   Timecop.return
 end
 
-lib = File.join(File.dirname(__FILE__), "../../spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib")
+lib = File.join(File.dirname(__FILE__), '../../spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib')
 $LOAD_PATH << lib
diff --git a/lib/stack_master.rb b/lib/stack_master.rb
index 5f94d8dc..d48ee779 100644
--- a/lib/stack_master.rb
+++ b/lib/stack_master.rb
@@ -172,7 +172,7 @@ def skip_account_check?
   @non_interactive_answer = 'y'
 
   def base_dir
-    File.expand_path(File.join(File.dirname(__FILE__), ".."))
+    File.expand_path(File.join(File.dirname(__FILE__), '..'))
   end
 
   def cloud_formation_driver
diff --git a/lib/stack_master/aws_driver/cloud_formation.rb b/lib/stack_master/aws_driver/cloud_formation.rb
index 2cc7b1b9..acdf1567 100644
--- a/lib/stack_master/aws_driver/cloud_formation.rb
+++ b/lib/stack_master/aws_driver/cloud_formation.rb
@@ -8,10 +8,10 @@ def region
       end
 
       def set_region(value)
-        if region != value
-          @region = value
-          @cf = nil
-        end
+        return if region == value
+
+        @region = value
+        @cf = nil
       end
 
       def_delegators(
diff --git a/lib/stack_master/aws_driver/s3.rb b/lib/stack_master/aws_driver/s3.rb
index 0f385b0d..2b66d238 100644
--- a/lib/stack_master/aws_driver/s3.rb
+++ b/lib/stack_master/aws_driver/s3.rb
@@ -24,11 +24,11 @@ def upload_files(bucket: nil, prefix: nil, region: nil, files: {})
             prefix: prefix,
             bucket: bucket
           }
-        ).map(&:contents).flatten.inject({}) { |h, obj|
+        ).map(&:contents).flatten.inject({}) do |h, obj|
           h.merge(obj.key => obj)
-        }
+        end
 
-        StackMaster.stdout.puts "Uploading files to S3:"
+        StackMaster.stdout.puts 'Uploading files to S3:'
 
         files.each do |template, file|
           body = file.fetch(:body)
@@ -36,7 +36,7 @@ def upload_files(bucket: nil, prefix: nil, region: nil, files: {})
           object_key = template.dup
           object_key.prepend("#{prefix}/") if prefix
           compiled_template_md5 = Digest::MD5.hexdigest(body).to_s
-          s3_md5 = current_objects[object_key] ? current_objects[object_key].etag.gsub("\"", '') : nil
+          s3_md5 = current_objects[object_key] ? current_objects[object_key].etag.gsub('"', '') : nil
 
           next if compiled_template_md5 == s3_md5
 
@@ -51,14 +51,14 @@ def upload_files(bucket: nil, prefix: nil, region: nil, files: {})
               metadata: { md5: compiled_template_md5 }
             }
           )
-          StackMaster.stdout.puts "done."
+          StackMaster.stdout.puts 'done.'
         end
       end
 
       def url(bucket:, prefix:, region:, template:)
         if region == 'us-east-1'
-          ["https://s3.amazonaws.com", bucket, prefix, template].compact.join('/')
-        elsif region.start_with? "cn-"
+          ['https://s3.amazonaws.com', bucket, prefix, template].compact.join('/')
+        elsif region.start_with? 'cn-'
           ["https://s3.#{region}.amazonaws.com.cn", bucket, prefix, template].compact.join('/')
         else
           ["https://s3-#{region}.amazonaws.com", bucket, prefix, template].compact.join('/')
diff --git a/lib/stack_master/change_set.rb b/lib/stack_master/change_set.rb
index 3d06ab79..23d91467 100644
--- a/lib/stack_master/change_set.rb
+++ b/lib/stack_master/change_set.rb
@@ -1,9 +1,9 @@
 module StackMaster
   class ChangeSet
-    END_STATES = [
-      'CREATE_COMPLETE',
-      'DELETE_COMPLETE',
-      'FAILED'
+    END_STATES = %w[
+      CREATE_COMPLETE
+      DELETE_COMPLETE
+      FAILED
     ]
 
     def self.generate_change_set_name(stack_name)
@@ -50,7 +50,7 @@ def display(io)
       @response.changes.each do |change|
         display_resource_change(io, change.resource_change)
       end
-      io.puts "========================================"
+      io.puts '========================================'
     end
 
     def failed?
@@ -84,13 +84,9 @@ def display_resource_change(io, resource_change)
     def display_resource_change_detail(io, action_name, color, detail)
       target_name = [detail.target.attribute, detail.target.name].compact.join('.')
       detail_messages = [target_name]
-      if action_name == 'Replace'
-        detail_messages << "#{detail.target.requires_recreation} requires recreation"
-      end
+      detail_messages << "#{detail.target.requires_recreation} requires recreation" if action_name == 'Replace'
       triggered_by = [detail.change_source, detail.causing_entity].compact.join('.')
-      if detail.evaluation != 'Static'
-        triggered_by << "(#{detail.evaluation})"
-      end
+      triggered_by << "(#{detail.evaluation})" if detail.evaluation != 'Static'
       detail_messages << "Triggered by: #{triggered_by}"
       io.puts Rainbow("- #{detail_messages.join('. ')}. ").color(color)
     end
diff --git a/lib/stack_master/cli.rb b/lib/stack_master/cli.rb
index 9ba31e45..b170c731 100644
--- a/lib/stack_master/cli.rb
+++ b/lib/stack_master/cli.rb
@@ -6,7 +6,11 @@ class CLI
     include Commander::Methods
 
     def initialize(argv, stdin = STDIN, stdout = STDOUT, stderr = STDERR, kernel = Kernel)
-      @argv, @stdin, @stdout, @stderr, @kernel = argv, stdin, stdout, stderr, kernel
+      @argv = argv
+      @stdin = stdin
+      @stdout = stdout
+      @stderr = stderr
+      @kernel = kernel
       Commander::Runner.instance_variable_set('@instance', Commander::Runner.new(argv))
       StackMaster.stdout = @stdout
       StackMaster.stderr = @stderr
@@ -49,7 +53,7 @@ def execute!
                  'Valid Values: [ DO_NOTHING | ROLLBACK | DELETE ]. ' \
                  "Default: ROLLBACK\n" \
                  'Note: You cannot use this option with Serverless Application Model (SAM) templates.'
-        c.option '--yes-param PARAM_NAME', String, "Auto-approve stack updates when only parameter PARAM_NAME changes"
+        c.option '--yes-param PARAM_NAME', String, 'Auto-approve stack updates when only parameter PARAM_NAME changes'
         c.action do |args, options|
           options.default config: default_config_file
           execute_stacks_command(StackMaster::Commands::Apply, args, options)
@@ -59,7 +63,7 @@ def execute!
       command :outputs do |c|
         c.syntax = 'stack_master outputs [region_or_alias] [stack_name]'
         c.summary = 'Displays outputs for a stack'
-        c.description = "Displays outputs for a stack"
+        c.description = 'Displays outputs for a stack'
         c.action do |args, options|
           options.default config: default_config_file
           execute_stacks_command(StackMaster::Commands::Outputs, args, options)
@@ -73,10 +77,10 @@ def execute!
         c.option('--overwrite', 'Overwrite existing files')
         c.action do |args, options|
           options.default config: default_config_file
-          unless args.size == 2
-            say "Invalid arguments. stack_master init [region] [stack_name]"
-          else
+          if args.size == 2
             StackMaster::Commands::Init.perform(options, *args)
+          else
+            say 'Invalid arguments. stack_master init [region] [stack_name]'
           end
         end
       end
@@ -94,8 +98,8 @@ def execute!
 
       command :events do |c|
         c.syntax = 'stack_master events [region_or_alias] [stack_name]'
-        c.summary = "Shows events for a stack"
-        c.description = "Shows events for a stack"
+        c.summary = 'Shows events for a stack'
+        c.description = 'Shows events for a stack'
         c.example 'show events for myapp-vpc in us-east-1', 'stack_master events us-east-1 myapp-vpc'
         c.option '--number Integer', Integer, 'Number of recent events to show'
         c.option '--all', 'Show all events'
@@ -108,8 +112,8 @@ def execute!
 
       command :resources do |c|
         c.syntax = 'stack_master resources [region] [stack_name]'
-        c.summary = "Shows stack resources"
-        c.description = "Shows stack resources"
+        c.summary = 'Shows stack resources'
+        c.description = 'Shows stack resources'
         c.action do |args, options|
           options.default config: default_config_file
           execute_stacks_command(StackMaster::Commands::Resources, args, options)
@@ -122,7 +126,7 @@ def execute!
         c.description = 'List stack definitions'
         c.action do |args, options|
           options.default config: default_config_file
-          say "Invalid arguments." if args.size > 0
+          say 'Invalid arguments.' if args.size > 0
           config = load_config(options.config)
           StackMaster::Commands::ListStacks.perform(config, nil, options)
         end
@@ -142,8 +146,8 @@ def execute!
 
       command :lint do |c|
         c.syntax = 'stack_master lint [region_or_alias] [stack_name]'
-        c.summary = "Check the stack definition locally"
-        c.description = "Runs cfn-lint on the template which would be sent to AWS on apply"
+        c.summary = 'Check the stack definition locally'
+        c.description = 'Runs cfn-lint on the template which would be sent to AWS on apply'
         c.example 'run cfn-lint on stack myapp-vpc with us-east-1 settings', 'stack_master lint us-east-1 myapp-vpc'
         c.action do |args, options|
           options.default config: default_config_file
@@ -154,7 +158,7 @@ def execute!
       command :nag do |c|
         c.syntax = 'stack_master nag [region_or_alias] [stack_name]'
         c.summary = "Check this stack's template with cfn_nag"
-        c.description = "Runs SAST scan cfn_nag on the template"
+        c.description = 'Runs SAST scan cfn_nag on the template'
         c.example 'run cfn_nag on stack myapp-vpc with us-east-1 settings', 'stack_master nag us-east-1 myapp-vpc'
         c.action do |args, options|
           options.default config: default_config_file
@@ -164,7 +168,7 @@ def execute!
 
       command :compile do |c|
         c.syntax = 'stack_master compile [region_or_alias] [stack_name]'
-        c.summary = "Print the compiled version of a given stack"
+        c.summary = 'Print the compiled version of a given stack'
         c.description = "Processes the stack and prints out a compiled version - same we'd send to AWS"
         c.example 'print compiled stack myapp-vpc with us-east-1 settings', 'stack_master compile us-east-1 myapp-vpc'
         c.action do |args, options|
@@ -181,7 +185,7 @@ def execute!
         c.example 'description', 'Check the status of all stack definitions'
         c.action do |args, options|
           options.default config: default_config_file
-          say "Invalid arguments. stack_master status" and return unless args.size == 0
+          say 'Invalid arguments. stack_master status' and return unless args.size == 0
 
           config = load_config(options.config)
           StackMaster::Commands::Status.perform(config, nil, options)
@@ -196,7 +200,7 @@ def execute!
         c.example 'description', 'Check for missing or extra files'
         c.action do |args, options|
           options.default config: default_config_file
-          say "Invalid arguments. stack_master tidy" and return unless args.size == 0
+          say 'Invalid arguments. stack_master tidy' and return unless args.size == 0
 
           config = load_config(options.config)
           StackMaster::Commands::Tidy.perform(config, nil, options)
@@ -211,7 +215,7 @@ def execute!
         c.action do |args, options|
           options.default config: default_config_file
           unless args.size == 2
-            say "Invalid arguments. stack_master delete [region] [stack_name]"
+            say 'Invalid arguments. stack_master delete [region] [stack_name]'
             return
           end
 
@@ -239,7 +243,7 @@ def execute!
         c.syntax = 'stack_master drift [region_or_alias] [stack_name]'
         c.summary = 'Detects and displays stack drift using the CloudFormation Drift API'
         c.description = 'Detects and displays stack drift'
-        c.option '--timeout SECONDS', Integer, "The number of seconds to wait for drift detection to complete"
+        c.option '--timeout SECONDS', Integer, 'The number of seconds to wait for drift detection to complete'
         c.example 'view stack drift for a stack named myapp-vpc in us-east-1', 'stack_master drift us-east-1 myapp-vpc'
         c.action do |args, options|
           options.default config: default_config_file, timeout: 120
@@ -253,7 +257,7 @@ def execute!
     private
 
     def default_config_file
-      "stack_master.yml"
+      'stack_master.yml'
     end
 
     def load_config(file)
@@ -277,10 +281,12 @@ def execute_stacks_command(command, args, options)
           show_other_region_candidates(config, stack_name)
           success = false
         end
-        stack_definitions = stack_definitions.select do |stack_definition|
-          running_in_allowed_account?(stack_definition.allowed_accounts) &&
-            StackStatus.new(config, stack_definition).changed?
-        end if options.changed
+        if options.changed
+          stack_definitions = stack_definitions.select do |stack_definition|
+            running_in_allowed_account?(stack_definition.allowed_accounts) &&
+              StackStatus.new(config, stack_definition).changed?
+          end
+        end
         stack_definitions.each do |stack_definition|
           StackMaster.cloud_formation_driver.set_region(stack_definition.region)
           StackMaster.stdout.puts(
@@ -295,14 +301,14 @@ def execute_stacks_command(command, args, options)
     end
 
     def show_other_region_candidates(config, stack_name)
-      candidates = config.filter(region = "", stack_name = stack_name)
+      candidates = config.filter(region = '', stack_name = stack_name)
       return if candidates.empty?
 
       StackMaster.stdout.puts "Stack name #{stack_name} exists in regions: #{candidates.map(&:region).join(', ')}"
     end
 
     def execute_if_allowed_account(allowed_accounts, &block)
-      raise ArgumentError, "Block required to execute this method" unless block_given?
+      raise ArgumentError, 'Block required to execute this method' unless block_given?
 
       if running_in_allowed_account?(allowed_accounts)
         block.call
diff --git a/lib/stack_master/command.rb b/lib/stack_master/command.rb
index 7e30f380..c20d8484 100644
--- a/lib/stack_master/command.rb
+++ b/lib/stack_master/command.rb
@@ -43,11 +43,7 @@ def error_message(e)
       msg = "#{e.class} #{e.message}"
       msg << "\n Caused by: #{e.cause.class} #{e.cause.message}" if e.cause
       msg << "\n at #{e.cause.backtrace[0..3].join("\n    ")}\n ..." if e.cause && !options.trace
-      if options.trace
-        msg << "\n#{backtrace(e)}"
-      else
-        msg << "\n Use --trace to view backtrace"
-      end
+      msg << (options.trace ? "\n#{backtrace(e)}" : "\n Use --trace to view backtrace")
       msg
     end
 
diff --git a/lib/stack_master/commands/apply.rb b/lib/stack_master/commands/apply.rb
index ba106855..46c3438f 100644
--- a/lib/stack_master/commands/apply.rb
+++ b/lib/stack_master/commands/apply.rb
@@ -44,10 +44,10 @@ def stack_exists?
       end
 
       def abort_if_review_in_progress
-        if stack_exists? && stack.stack_status == "REVIEW_IN_PROGRESS"
-          StackMaster.stderr.puts "Stack currently exists and is in #{stack.stack_status}"
-          failed! "You will need to delete the stack (#{stack.stack_name}) before continuing"
-        end
+        return unless stack_exists? && stack.stack_status == 'REVIEW_IN_PROGRESS'
+
+        StackMaster.stderr.puts "Stack currently exists and is in #{stack.stack_status}"
+        failed! "You will need to delete the stack (#{stack.stack_name}) before continuing"
       end
 
       def use_s3?
@@ -111,11 +111,11 @@ def create_stack_directly
       end
 
       def ask_to_cancel_stack_update
-        if ask?("Cancel stack update?")
-          StackMaster.stdout.puts "Attempting to cancel stack update"
-          cf.cancel_update_stack(stack_name: stack_name)
-          tail_stack_events
-        end
+        return unless ask?('Cancel stack update?')
+
+        StackMaster.stdout.puts 'Attempting to cancel stack update'
+        cf.cancel_update_stack(stack_name: stack_name)
+        tail_stack_events
       end
 
       def update_stack
@@ -136,10 +136,10 @@ def update_stack
       end
 
       def ask_update_confirmation!
-        unless ask?("Apply change set (y/n)? ")
-          ChangeSet.delete(@change_set.id)
-          halt! "Stack update aborted"
-        end
+        return if ask?('Apply change set (y/n)? ')
+
+        ChangeSet.delete(@change_set.id)
+        halt! 'Stack update aborted'
       end
 
       def upload_files
@@ -177,7 +177,7 @@ def stack_options
           stack_name: stack_name,
           parameters: proposed_stack.aws_parameters,
           tags: proposed_stack.aws_tags,
-          capabilities: ['CAPABILITY_IAM', 'CAPABILITY_NAMED_IAM', 'CAPABILITY_AUTO_EXPAND'],
+          capabilities: %w[CAPABILITY_IAM CAPABILITY_NAMED_IAM CAPABILITY_AUTO_EXPAND],
           role_arn: proposed_stack.role_arn,
           notification_arns: proposed_stack.notification_arns,
           template_method => template_value
@@ -211,9 +211,9 @@ def ensure_valid_parameters!
       end
 
       def ensure_valid_template_body_size!
-        if proposed_stack.too_big?(use_s3?)
-          failed! TEMPLATE_TOO_LARGE_ERROR_MESSAGE
-        end
+        return unless proposed_stack.too_big?(use_s3?)
+
+        failed! TEMPLATE_TOO_LARGE_ERROR_MESSAGE
       end
 
       def set_stack_policy
diff --git a/lib/stack_master/commands/delete.rb b/lib/stack_master/commands/delete.rb
index 9e86006c..cc09e4e2 100644
--- a/lib/stack_master/commands/delete.rb
+++ b/lib/stack_master/commands/delete.rb
@@ -15,7 +15,7 @@ def perform
         return unless check_exists
 
         unless ask?("Really delete stack #{@stack_name} (y/n)? ")
-          StackMaster.stdout.puts "Stack update aborted"
+          StackMaster.stdout.puts 'Stack update aborted'
           return
         end
 
@@ -33,7 +33,7 @@ def check_exists
         cf.describe_stacks({ stack_name: @stack_name })
         true
       rescue Aws::CloudFormation::Errors::ValidationError
-        failed("Stack does not exist")
+        failed('Stack does not exist')
         false
       end
 
@@ -43,10 +43,10 @@ def cf
 
       def tail_stack_events
         StackEvents::Streamer.stream(@stack_name, @region, io: StackMaster.stdout, from: @from_time)
-        StackMaster.stdout.puts "Stack deleted"
+        StackMaster.stdout.puts 'Stack deleted'
       rescue Aws::CloudFormation::Errors::ValidationError
         # Unfortunately the stack as a tendency of going away before we get the final delete event.
-        StackMaster.stdout.puts "Stack deleted"
+        StackMaster.stdout.puts 'Stack deleted'
       end
     end
   end
diff --git a/lib/stack_master/commands/drift.rb b/lib/stack_master/commands/drift.rb
index a3e9858c..812f9e0f 100644
--- a/lib/stack_master/commands/drift.rb
+++ b/lib/stack_master/commands/drift.rb
@@ -6,9 +6,9 @@ class Drift
       include Command
       include Commander::UI
 
-      DETECTION_COMPLETE_STATES = [
-        'DETECTION_COMPLETE',
-        'DETECTION_FAILED'
+      DETECTION_COMPLETE_STATES = %w[
+        DETECTION_COMPLETE
+        DETECTION_FAILED
       ]
 
       def perform
@@ -41,9 +41,7 @@ def display_drift(drift)
                        drift.physical_resource_id].join(' '), color)
         return unless drift.stack_resource_drift_status == 'MODIFIED'
 
-        unless drift.property_differences.empty?
-          puts colorize('  Property differences:', color)
-        end
+        puts colorize('  Property differences:', color) unless drift.property_differences.empty?
         drift.property_differences.each do |property_difference|
           puts colorize("  - #{property_difference.difference_type} #{property_difference.property_path}", color)
         end
@@ -98,9 +96,7 @@ def wait_for_drift_results(detection_id)
           break if DETECTION_COMPLETE_STATES.include?(resp.detection_status)
 
           elapsed_time = Time.now - start_time
-          if elapsed_time > @options.timeout
-            raise "Timeout waiting for stack drift detection"
-          end
+          raise 'Timeout waiting for stack drift detection' if elapsed_time > @options.timeout
 
           sleep SLEEP_SECONDS
         end
diff --git a/lib/stack_master/commands/events.rb b/lib/stack_master/commands/events.rb
index 9e1b163a..78ece8d3 100644
--- a/lib/stack_master/commands/events.rb
+++ b/lib/stack_master/commands/events.rb
@@ -9,9 +9,9 @@ def perform
         filter_events(events).each do |event|
           StackEvents::Presenter.print_event(StackMaster.stdout, event)
         end
-        if @options.tail
-          StackEvents::Streamer.stream(@stack_definition.stack_name, @stack_definition.region, io: StackMaster.stdout)
-        end
+        return unless @options.tail
+
+        StackEvents::Streamer.stream(@stack_definition.stack_name, @stack_definition.region, io: StackMaster.stdout)
       end
 
       private
@@ -22,9 +22,7 @@ def filter_events(events)
         else
           n = @options.number || 25
           from = events.count - n
-          if from < 0
-            from = 0
-          end
+          from = 0 if from < 0
           events[from..-1]
         end
       end
diff --git a/lib/stack_master/commands/init.rb b/lib/stack_master/commands/init.rb
index b82f75e4..b8dc8aa3 100644
--- a/lib/stack_master/commands/init.rb
+++ b/lib/stack_master/commands/init.rb
@@ -1,4 +1,4 @@
-require "erb"
+require 'erb'
 
 module StackMaster
   module Commands
@@ -12,22 +12,22 @@ def initialize(options, region, stack_name)
       end
 
       def perform
-        if check_files
-          create_stack_master_yml
-          create_stack_json_yml
-          create_parameters_yml
-        end
+        return unless check_files
+
+        create_stack_master_yml
+        create_stack_json_yml
+        create_parameters_yml
       end
 
       private
 
       def check_files
-        @stack_master_filename = "stack_master.yml"
+        @stack_master_filename = 'stack_master.yml'
         @stack_json_filename = "templates/#{@stack_name}.json"
-        @parameters_filename = File.join("parameters", "#{@stack_name}.yml")
-        @region_parameters_filename = File.join("parameters", @region, "#{@stack_name}.yml")
+        @parameters_filename = File.join('parameters', "#{@stack_name}.yml")
+        @region_parameters_filename = File.join('parameters', @region, "#{@stack_name}.yml")
 
-        if !@options.overwrite
+        unless @options.overwrite
           [@stack_master_filename, @stack_json_filename, @parameters_filename,
            @region_parameters_filename].each do |filename|
             next unless File.exist?(filename)
@@ -50,7 +50,7 @@ def stack_json_output
       end
 
       def stack_json_template
-        File.join(StackMaster.base_dir, "stacktemplates", "stack.json.erb")
+        File.join(StackMaster.base_dir, 'stacktemplates', 'stack.json.erb')
       end
 
       def create_stack_master_yml
@@ -63,7 +63,7 @@ def stack_master_yml_output
       end
 
       def stack_master_template
-        File.join(StackMaster.base_dir, "stacktemplates", "stack_master.yml.erb")
+        File.join(StackMaster.base_dir, 'stacktemplates', 'stack_master.yml.erb')
       end
 
       def create_parameters_yml
@@ -83,11 +83,11 @@ def parameter_region_yml_output
       end
 
       def parameter_stack_name_template
-        File.join(StackMaster.base_dir, "stacktemplates", "parameter_stack_name.yml")
+        File.join(StackMaster.base_dir, 'stacktemplates', 'parameter_stack_name.yml')
       end
 
       def parameter_region_template
-        File.join(StackMaster.base_dir, "stacktemplates", "parameter_region.yml")
+        File.join(StackMaster.base_dir, 'stacktemplates', 'parameter_region.yml')
       end
 
       def render(renderer)
diff --git a/lib/stack_master/commands/lint.rb b/lib/stack_master/commands/lint.rb
index 139d30a1..37e95f0f 100644
--- a/lib/stack_master/commands/lint.rb
+++ b/lib/stack_master/commands/lint.rb
@@ -19,7 +19,7 @@ def perform
           f.write(proposed_stack.template_body)
           f.flush
           system('cfn-lint', f.path)
-          puts "cfn-lint run complete"
+          puts 'cfn-lint run complete'
         end
       end
 
diff --git a/lib/stack_master/commands/list_stacks.rb b/lib/stack_master/commands/list_stacks.rb
index 1269857c..5f06ef5a 100644
--- a/lib/stack_master/commands/list_stacks.rb
+++ b/lib/stack_master/commands/list_stacks.rb
@@ -8,7 +8,7 @@ class ListStacks
       include StackMaster::Commands::TerminalHelper
 
       def perform
-        tp.set :max_width, self.window_size
+        tp.set :max_width, window_size
         tp @config.stacks, :region, :stack_name
       end
     end
diff --git a/lib/stack_master/commands/outputs.rb b/lib/stack_master/commands/outputs.rb
index 658e04a3..df478fa9 100644
--- a/lib/stack_master/commands/outputs.rb
+++ b/lib/stack_master/commands/outputs.rb
@@ -9,7 +9,7 @@ class Outputs
 
       def perform
         if stack
-          tp.set :max_width, self.window_size
+          tp.set :max_width, window_size
           tp stack.outputs, :output_key, :output_value, :description
         else
           failed("Stack doesn't exist")
diff --git a/lib/stack_master/commands/status.rb b/lib/stack_master/commands/status.rb
index 57762053..4d6f1c94 100644
--- a/lib/stack_master/commands/status.rb
+++ b/lib/stack_master/commands/status.rb
@@ -21,11 +21,11 @@ def perform
           {
             region: stack_definition.region,
             stack_name: stack_definition.stack_name,
-            stack_status: running_in_allowed_account?(allowed_accounts) ? stack_status.status : "Disallowed account",
-            different: running_in_allowed_account?(allowed_accounts) ? stack_status.changed_message : "N/A",
+            stack_status: running_in_allowed_account?(allowed_accounts) ? stack_status.status : 'Disallowed account',
+            different: running_in_allowed_account?(allowed_accounts) ? stack_status.changed_message : 'N/A'
           }
         end
-        tp.set :max_width, self.window_size
+        tp.set :max_width, window_size
         tp.set :io, StackMaster.stdout
         tp status
         StackMaster.stdout.puts " * No echo parameters can't be diffed"
@@ -34,7 +34,7 @@ def perform
       private
 
       def progress
-        @progress ||= ProgressBar.create(title: "Fetching stack information",
+        @progress ||= ProgressBar.create(title: 'Fetching stack information',
                                          total: @config.stacks.size,
                                          output: StackMaster.stdout)
       end
diff --git a/lib/stack_master/commands/terminal_helper.rb b/lib/stack_master/commands/terminal_helper.rb
index be3acc72..ef5d191a 100644
--- a/lib/stack_master/commands/terminal_helper.rb
+++ b/lib/stack_master/commands/terminal_helper.rb
@@ -4,9 +4,9 @@ module StackMaster
   module Commands
     module TerminalHelper
       def window_size
-        size = ENV.fetch("COLUMNS") { OS.windows? ? windows_window_size : unix_window_size }
+        size = ENV.fetch('COLUMNS') { OS.windows? ? windows_window_size : unix_window_size }
 
-        if size.nil? || size == ""
+        if size.nil? || size == ''
           80
         else
           size.to_i
@@ -18,7 +18,7 @@ def unix_window_size
       end
 
       def windows_window_size
-        columns_regex = %r{^\s+Columns:\s+([0-9]+)$}
+        columns_regex = /^\s+Columns:\s+([0-9]+)$/
         output = `mode con`
         columns_line = output.split("\n").select { |line| line.match(columns_regex) }.last
         columns_line.match(columns_regex)[1]
diff --git a/lib/stack_master/commands/tidy.rb b/lib/stack_master/commands/tidy.rb
index 078adf3a..49e3be51 100644
--- a/lib/stack_master/commands/tidy.rb
+++ b/lib/stack_master/commands/tidy.rb
@@ -8,23 +8,23 @@ def perform
         used_templates = []
         used_parameter_files = []
 
-        templates = Set.new(find_templates())
-        parameter_files = Set.new(find_parameter_files())
+        templates = Set.new(find_templates)
+        parameter_files = Set.new(find_parameter_files)
 
         status = @config.stacks.each do |stack_definition|
           parameter_files.subtract(stack_definition.parameter_files_from_globs)
           template = File.absolute_path(stack_definition.template_file_path)
 
-          if template
-            templates.delete(template)
+          next unless template
 
-            if !File.exist?(template)
-              StackMaster.stdout.puts(
-                "Stack \"#{stack_definition.stack_name}\" in \"#{stack_definition.region}\" " \
-                "missing template \"#{rel_path(template)}\""
-              )
-            end
-          end
+          templates.delete(template)
+
+          next if File.exist?(template)
+
+          StackMaster.stdout.puts(
+            "Stack \"#{stack_definition.stack_name}\" in \"#{stack_definition.region}\" " \
+            "missing template \"#{rel_path(template)}\""
+          )
         end
 
         templates.each do |path|
@@ -46,21 +46,19 @@ def find_templates
         # template directories) this won't find the right directory.
         template_dir = @config.template_dir || File.join(@config.base_dir, 'templates')
 
-        templates = Dir.glob(File.absolute_path(File.join(template_dir, '**', "*.{rb,yaml,yml,json}")))
+        templates = Dir.glob(File.absolute_path(File.join(template_dir, '**', '*.{rb,yaml,yml,json}')))
         dynamics_dir = File.join(template_dir, 'dynamics')
 
         # Exclude sparkleformation dynamics
         # TODO: Should this filter out anything with 'dynamics', not just the first
         # subdirectory?
-        templates = templates.select do |path|
+        templates.select do |path|
           !path.start_with?(dynamics_dir)
         end
-
-        templates
       end
 
       def find_parameter_files
-        Dir.glob(File.absolute_path(File.join(@config.base_dir, "parameters", "*.{yml,yaml}")))
+        Dir.glob(File.absolute_path(File.join(@config.base_dir, 'parameters', '*.{yml,yaml}')))
       end
     end
   end
diff --git a/lib/stack_master/config.rb b/lib/stack_master/config.rb
index b4cbbbbc..d332a398 100644
--- a/lib/stack_master/config.rb
+++ b/lib/stack_master/config.rb
@@ -26,13 +26,13 @@ def self.load!(config_file = 'stack_master.yml')
     )
 
     def self.search_up_and_chdir(config_file)
-      return config_file unless File.dirname(config_file) == "."
+      return config_file unless File.dirname(config_file) == '.'
 
       dir = Dir.pwd
-      parent_dir = File.expand_path("..", Dir.pwd)
+      parent_dir = File.expand_path('..', Dir.pwd)
       while parent_dir != dir && !File.exist?(File.join(dir, config_file))
         dir = parent_dir
-        parent_dir = File.expand_path("..", dir)
+        parent_dir = File.expand_path('..', dir)
       end
 
       File.join(dir, config_file)
@@ -45,10 +45,9 @@ def initialize(config, base_dir)
       @parameters_dir = config.fetch('parameters_dir', nil)
       @stack_defaults = config.fetch('stack_defaults', {})
       @region_aliases = Utils.underscore_keys_to_hyphen(config.fetch('region_aliases', {}))
-      @region_to_aliases = @region_aliases.inject({}) do |hash, (key, value)|
+      @region_to_aliases = @region_aliases.each_with_object({}) do |(key, value), hash|
         hash[value] ||= []
         hash[value] << key
-        hash
       end
       @region_defaults = normalise_region_defaults(config.fetch('region_defaults', {}))
       @stacks = []
@@ -86,7 +85,7 @@ def merge_defaults_to_user_defined_compilers
       @template_compilers = default_template_compilers.merge(@template_compilers)
     end
 
-    def populate_template_compilers user_defined_compilers
+    def populate_template_compilers(user_defined_compilers)
       user_defined_compilers.each do |key, val|
         @template_compilers[key.to_sym] = val.to_sym
       end
@@ -98,7 +97,7 @@ def default_template_compilers
         json: :json,
         yml: :yaml,
         yaml: :yaml,
-        erb: :yaml_erb,
+        erb: :yaml_erb
       }
     end
 
@@ -108,9 +107,8 @@ def load_config
     end
 
     def resolve_region_aliases(stacks)
-      stacks.inject({}) do |hash, (region, attributes)|
+      stacks.each_with_object({}) do |(region, attributes), hash|
         hash[unalias_region(region)] = attributes
-        hash
       end
     end
 
@@ -141,10 +139,9 @@ def build_stack_defaults(region)
     end
 
     def normalise_region_defaults(region_defaults)
-      region_defaults.inject({}) do |normalised_aliases, (region_or_alias, value)|
+      region_defaults.each_with_object({}) do |(region_or_alias, value), normalised_aliases|
         region = unalias_region(region_or_alias)
         normalised_aliases[Utils.underscore_to_hyphen(region)] = value
-        normalised_aliases
       end
     end
   end
diff --git a/lib/stack_master/diff.rb b/lib/stack_master/diff.rb
index c55dadb9..4d4c5442 100644
--- a/lib/stack_master/diff.rb
+++ b/lib/stack_master/diff.rb
@@ -1,6 +1,6 @@
 module StackMaster
   class Diff
-    def initialize(name: nil, before:, after:, context: 10_000)
+    def initialize(before:, after:, name: nil, context: 10_000)
       @name = name
       @before = before
       @after = after
@@ -10,7 +10,7 @@ def initialize(name: nil, before:, after:, context: 10_000)
     def display
       stdout.print "#{@name} diff: "
       if diff == ''
-        stdout.puts "No changes"
+        stdout.puts 'No changes'
       else
         stdout.puts
         display_colorized_diff
diff --git a/lib/stack_master/parameter_loader.rb b/lib/stack_master/parameter_loader.rb
index 4d62cb87..a9baf4e3 100644
--- a/lib/stack_master/parameter_loader.rb
+++ b/lib/stack_master/parameter_loader.rb
@@ -7,13 +7,12 @@ class ParameterLoader
     def self.load(parameter_files: [], parameters: {})
       StackMaster.debug 'Searching for parameter files...'
       all_parameters = parameter_files.map { |file_name| load_parameters(file_name) } + [parameters]
-      all_parameters.reduce({ template_parameters: {}, compile_time_parameters: {} }) do |hash, parameters|
+      all_parameters.each_with_object({ template_parameters: {}, compile_time_parameters: {} }) do |parameters, hash|
         template_parameters = create_template_parameters(parameters)
         compile_time_parameters = create_compile_time_parameters(parameters)
 
         merge_and_camelize(hash[:template_parameters], template_parameters)
         merge_and_camelize(hash[:compile_time_parameters], compile_time_parameters)
-        hash
       end
     end
 
diff --git a/lib/stack_master/parameter_resolver.rb b/lib/stack_master/parameter_resolver.rb
index 8e316408..6d5d47f9 100644
--- a/lib/stack_master/parameter_resolver.rb
+++ b/lib/stack_master/parameter_resolver.rb
@@ -15,13 +15,12 @@ def initialize(config, stack_definition, parameters)
     end
 
     def resolve
-      @parameters.reduce({}) do |parameters, (key, value)|
+      @parameters.each_with_object({}) do |(key, value), parameters|
         begin
           parameters[key] = resolve_parameter_value(key, value)
         rescue InvalidParameter
           raise InvalidParameter, "Unable to resolve parameter #{key.inspect} value causing error: #{$!.message}"
         end
-        parameters
       end
     end
 
@@ -30,11 +29,9 @@ def resolve
     def require_parameter_resolver(file_name)
       require "stack_master/parameter_resolvers/#{file_name}"
     rescue LoadError
-      if file_name == file_name.singularize
-        raise ResolverNotFound.new(file_name)
-      else
-        require_parameter_resolver(file_name.singularize)
-      end
+      raise ResolverNotFound.new(file_name) if file_name == file_name.singularize
+
+      require_parameter_resolver(file_name.singularize)
     end
 
     def load_parameter_resolver(class_name)
@@ -46,9 +43,11 @@ def load_parameter_resolver(class_name)
     end
 
     def resolve_parameter_value(key, parameter_value)
-      return parameter_value.to_s if Numeric === parameter_value || parameter_value == true || parameter_value == false
-      return resolve_array_parameter_values(key, parameter_value).join(',') if Array === parameter_value
-      return parameter_value unless Hash === parameter_value
+      if parameter_value.is_a?(Numeric) || parameter_value == true || parameter_value == false
+        return parameter_value.to_s
+      end
+      return resolve_array_parameter_values(key, parameter_value).join(',') if parameter_value.is_a?(Array)
+      return parameter_value unless parameter_value.is_a?(Hash)
 
       resolve_parameter_resolver_hash(key, parameter_value)
     rescue Aws::CloudFormation::Errors::ValidationError
@@ -73,15 +72,13 @@ def resolve_parameter_resolver_hash(key, parameter_value)
       end
     end
 
-    def assume_role_if_present(account, role, key)
+    def assume_role_if_present(account, role, key, &block)
       return yield if account.nil? && role.nil?
       if account.nil? || role.nil?
         raise InvalidParameter, "Both 'account' and 'role' are required to assume role for parameter '#{key}'"
       end
 
-      role_assumer.assume_role(account, role) do
-        yield
-      end
+      role_assumer.assume_role(account, role, &block)
     end
 
     def resolve_array_parameter_values(key, parameter_values)
@@ -114,9 +111,9 @@ def resolver_class(class_name)
     end
 
     def validate_parameter_value!(key, parameter_value)
-      if parameter_value.keys.size != 1
-        raise InvalidParameter, "#{key} hash contained more than one key: #{parameter_value.inspect}"
-      end
+      return if parameter_value.keys.size == 1
+
+      raise InvalidParameter, "#{key} hash contained more than one key: #{parameter_value.inspect}"
     end
 
     def role_assumer
diff --git a/lib/stack_master/parameter_resolvers/ami_finder.rb b/lib/stack_master/parameter_resolvers/ami_finder.rb
index d079a3a6..d2cff117 100644
--- a/lib/stack_master/parameter_resolvers/ami_finder.rb
+++ b/lib/stack_master/parameter_resolvers/ami_finder.rb
@@ -6,12 +6,11 @@ def initialize(region)
       end
 
       def build_filters_from_string(value, prefix = nil)
-        filters = value.split(',').map do |name_with_value|
+        value.split(',').map do |name_with_value|
           name, value = name_with_value.strip.split('=')
           name = prefix ? "#{prefix}:#{name}" : name
           { name: name, values: [value] }
         end
-        filters
       end
 
       def build_filters_from_hash(hash)
diff --git a/lib/stack_master/parameter_resolvers/ejson.rb b/lib/stack_master/parameter_resolvers/ejson.rb
index 26a01f76..e1cc241a 100644
--- a/lib/stack_master/parameter_resolvers/ejson.rb
+++ b/lib/stack_master/parameter_resolvers/ejson.rb
@@ -22,10 +22,10 @@ def resolve(secret_key)
       private
 
       def validate_ejson_file_specified
-        if @stack_definition.ejson_file.nil?
-          raise ArgumentError, 'No ejson_file defined for stack definition ' \
-                               "#{@stack_definition.stack_name} in #{@stack_definition.region}"
-        end
+        return unless @stack_definition.ejson_file.nil?
+
+        raise ArgumentError, 'No ejson_file defined for stack definition ' \
+                             "#{@stack_definition.stack_name} in #{@stack_definition.region}"
       end
 
       def decrypt_ejson_file
diff --git a/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb b/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
index 5874c258..af1416fd 100644
--- a/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
+++ b/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
@@ -10,7 +10,7 @@ def initialize(config, stack_definition)
       end
 
       def resolve(value)
-        filters = @ami_finder.build_filters_from_string(value, prefix = "tag")
+        filters = @ami_finder.build_filters_from_string(value, prefix = 'tag')
         @ami_finder.find_latest_ami(filters)&.image_id
       end
     end
diff --git a/lib/stack_master/parameter_resolvers/latest_container.rb b/lib/stack_master/parameter_resolvers/latest_container.rb
index cf38aa18..a6d87edb 100644
--- a/lib/stack_master/parameter_resolvers/latest_container.rb
+++ b/lib/stack_master/parameter_resolvers/latest_container.rb
@@ -10,7 +10,7 @@ def initialize(config, stack_definition)
 
       def resolve(parameters)
         if parameters['repository_name'].nil?
-          raise ArgumentError, "repository_name parameter is required but was not supplied"
+          raise ArgumentError, 'repository_name parameter is required but was not supplied'
         end
 
         @region = parameters['region'] || @stack_definition.region
@@ -43,8 +43,8 @@ def fetch_images(repository_name, registry_id, ecr)
             registry_id: registry_id,
             next_token: next_token,
             filter: {
-              tag_status: "TAGGED",
-            },
+              tag_status: 'TAGGED'
+            }
           }
         )
 
diff --git a/lib/stack_master/parameter_resolvers/one_password.rb b/lib/stack_master/parameter_resolvers/one_password.rb
index 01629dc0..8ee04880 100644
--- a/lib/stack_master/parameter_resolvers/one_password.rb
+++ b/lib/stack_master/parameter_resolvers/one_password.rb
@@ -16,7 +16,7 @@ def initialize(config, stack_definition)
       def resolve(params = {})
         if ENV.keys.grep(/OP_SESSION_\w+$/).empty?
           raise OnePasswordNotAbleToAuthenticate,
-                "1password requires the `OP_SESSION_<name>` to be set, (remember to sign in?)"
+                '1password requires the `OP_SESSION_<name>` to be set, (remember to sign in?)'
         end
 
         get_items(params)
@@ -25,7 +25,7 @@ def resolve(params = {})
       private
 
       def validate_op_installed?
-        %x(op --version)
+        `op --version`
       rescue Errno::ENOENT => exception
         raise OnePasswordBinaryNotFound, "The op cli needs to be installed and in the PATH, #{exception}"
       end
@@ -53,7 +53,7 @@ def login_item(data)
 
       def op_get_item(item, vault)
         validate_op_installed?
-        item = %x(op get item --vault='#{vault}' '#{item}' 2>&1)
+        item = `op get item --vault='#{vault}' '#{item}' 2>&1`
         item if validate_response?(item)
       end
 
@@ -79,9 +79,9 @@ def get_secure_note(title, vault)
       def get_items(params)
         case params['type']
         when 'password'
-          return get_password(params['title'], params['vault'])
+          get_password(params['title'], params['vault'])
         when 'secureNote'
-          return get_secure_note(params['title'], params['vault'])
+          get_secure_note(params['title'], params['vault'])
         end
       end
     end
diff --git a/lib/stack_master/parameter_resolvers/sso_group_id.rb b/lib/stack_master/parameter_resolvers/sso_group_id.rb
index b1743e9a..3bf5ed71 100644
--- a/lib/stack_master/parameter_resolvers/sso_group_id.rb
+++ b/lib/stack_master/parameter_resolvers/sso_group_id.rb
@@ -15,7 +15,7 @@ def resolve(value)
       private
 
       def sso_group_id_finder
-        StackMaster::SsoGroupIdFinder.new()
+        StackMaster::SsoGroupIdFinder.new
       end
     end
   end
diff --git a/lib/stack_master/parameter_resolvers/stack_output.rb b/lib/stack_master/parameter_resolvers/stack_output.rb
index 01379a2f..a6dd4992 100644
--- a/lib/stack_master/parameter_resolvers/stack_output.rb
+++ b/lib/stack_master/parameter_resolvers/stack_output.rb
@@ -17,18 +17,14 @@ def initialize(config, stack_definition)
       def resolve(value)
         region, stack_name, output_name = parse!(value)
         stack = find_stack(stack_name, region)
-        if stack
-          output = stack.outputs.find do |stack_output|
-            stack_output.output_key == output_name.camelize || stack_output.output_key == output_name
-          end
-          if output
-            output.output_value
-          else
-            raise StackOutputNotFound, "Stack exists (#{stack_name}), but output does not: #{output_name}"
-          end
-        else
-          raise StackNotFound, "Stack in StackOutput not found: #{value}"
+        raise StackNotFound, "Stack in StackOutput not found: #{value}" unless stack
+
+        output = stack.outputs.find do |stack_output|
+          stack_output.output_key == output_name.camelize || stack_output.output_key == output_name
         end
+        raise StackOutputNotFound, "Stack exists (#{stack_name}), but output does not: #{output_name}" unless output
+
+        output.output_value
       end
 
       private
diff --git a/lib/stack_master/parameter_validator.rb b/lib/stack_master/parameter_validator.rb
index e6e0b8c2..b80e726a 100644
--- a/lib/stack_master/parameter_validator.rb
+++ b/lib/stack_master/parameter_validator.rb
@@ -14,11 +14,7 @@ def error_message
       missing_parameters.each do |parameter_name|
         message << " - #{parameter_name}\n"
       end
-      if @stack_definition.parameter_files.empty?
-        message << message_for_parameter_globs
-      else
-        message << message_for_parameter_files
-      end
+      message << (@stack_definition.parameter_files.empty? ? message_for_parameter_globs : message_for_parameter_files)
       message
     end
 
diff --git a/lib/stack_master/prompter.rb b/lib/stack_master/prompter.rb
index b132ed62..99b24435 100644
--- a/lib/stack_master/prompter.rb
+++ b/lib/stack_master/prompter.rb
@@ -10,7 +10,7 @@ def ask?(question)
             StackMaster.stdin.getch.chomp
           else
             StackMaster.stdout.puts
-            StackMaster.stdout.puts "STDOUT or STDIN was not a TTY. Defaulting to no. To force yes use -y"
+            StackMaster.stdout.puts 'STDOUT or STDIN was not a TTY. Defaulting to no. To force yes use -y'
             'n'
           end
         else
diff --git a/lib/stack_master/resolver_array.rb b/lib/stack_master/resolver_array.rb
index c4e8f341..a5d09bc9 100644
--- a/lib/stack_master/resolver_array.rb
+++ b/lib/stack_master/resolver_array.rb
@@ -13,13 +13,13 @@ def resolve(values)
       end
 
       def resolver_class
-        fail "Method resolver_class not implemented on #{self.class}"
+        raise "Method resolver_class not implemented on #{self.class}"
       end
     end
 
     class Resolver
       def self.array_resolver(options = {})
-        resolver_class ||= Object.const_get(self.name)
+        resolver_class ||= Object.const_get(name)
         array_resolver_class_name = options[:class_name] || resolver_class.to_s.demodulize.pluralize
 
         klass = Class.new(ResolverArray) do
diff --git a/lib/stack_master/role_assumer.rb b/lib/stack_master/role_assumer.rb
index ab67804a..941a5b63 100644
--- a/lib/stack_master/role_assumer.rb
+++ b/lib/stack_master/role_assumer.rb
@@ -48,7 +48,7 @@ def assume_role_credentials(account, role)
           {
             region: StackMaster.cloud_formation_driver.region,
             role_arn: "arn:aws:iam::#{account}:role/#{role}",
-            role_session_name: "stack-master-role-assumer"
+            role_session_name: 'stack-master-role-assumer'
           }
         )
       end
diff --git a/lib/stack_master/security_group_finder.rb b/lib/stack_master/security_group_finder.rb
index 8398ca1d..455736f7 100644
--- a/lib/stack_master/security_group_finder.rb
+++ b/lib/stack_master/security_group_finder.rb
@@ -15,10 +15,10 @@ def find(reference)
       groups = @resource.security_groups({
                                            filters: [
                                              {
-                                               name: "group-name",
-                                               values: [reference],
-                                             },
-                                           ],
+                                               name: 'group-name',
+                                               values: [reference]
+                                             }
+                                           ]
                                          })
 
       raise SecurityGroupNotFound, "No security group with name #{reference} found" unless groups.any?
diff --git a/lib/stack_master/sns_topic_finder.rb b/lib/stack_master/sns_topic_finder.rb
index ee06d118..607d7ec1 100644
--- a/lib/stack_master/sns_topic_finder.rb
+++ b/lib/stack_master/sns_topic_finder.rb
@@ -21,7 +21,7 @@ def find(reference)
     private
 
     def topic_name_from_arn(arn)
-      arn.split(":")[5]
+      arn.split(':')[5]
     end
   end
 end
diff --git a/lib/stack_master/sparkle_formation/compile_time/allowed_pattern_validator.rb b/lib/stack_master/sparkle_formation/compile_time/allowed_pattern_validator.rb
index 94bd673b..a2c25a1c 100644
--- a/lib/stack_master/sparkle_formation/compile_time/allowed_pattern_validator.rb
+++ b/lib/stack_master/sparkle_formation/compile_time/allowed_pattern_validator.rb
@@ -22,7 +22,7 @@ def check_is_valid
 
         def invalid_values
           values = build_values(@definition, @parameter)
-          values.reject { |value| value.to_s.match(%r{#{@definition[KEY]}}) }
+          values.reject { |value| value.to_s.match(/#{@definition[KEY]}/) }
         end
 
         def create_error
diff --git a/lib/stack_master/sparkle_formation/compile_time/definitions_validator.rb b/lib/stack_master/sparkle_formation/compile_time/definitions_validator.rb
index 574e90ef..3c087fb4 100644
--- a/lib/stack_master/sparkle_formation/compile_time/definitions_validator.rb
+++ b/lib/stack_master/sparkle_formation/compile_time/definitions_validator.rb
@@ -4,7 +4,7 @@ module StackMaster
   module SparkleFormation
     module CompileTime
       class DefinitionsValidator
-        VALID_TYPES = [:string, :number]
+        VALID_TYPES = %i[string number]
         def initialize(definitions)
           @definitions = definitions
         end
diff --git a/lib/stack_master/sparkle_formation/compile_time/value_builder.rb b/lib/stack_master/sparkle_formation/compile_time/value_builder.rb
index 60eebe27..f35767f2 100644
--- a/lib/stack_master/sparkle_formation/compile_time/value_builder.rb
+++ b/lib/stack_master/sparkle_formation/compile_time/value_builder.rb
@@ -21,16 +21,16 @@ def parameter_or_default
         end
 
         def convert_strings_to_array
-          if @definition[:multiple] && @value.is_a?(String)
-            @value = @value.split(',').map(&:strip)
-          end
+          return unless @definition[:multiple] && @value.is_a?(String)
+
+          @value = @value.split(',').map(&:strip)
         end
 
         def convert_strings_to_numbers
-          if @definition[:type] == :number
-            @value = @value.to_f if @value.is_a?(String)
-            @value = @value.map { |item| item.is_a?(String) ? item.to_f : item } if @value.is_a?(Array)
-          end
+          return if @definition[:type] != :number
+
+          @value = @value.to_f if @value.is_a?(String)
+          @value = @value.map { |item| item.is_a?(String) ? item.to_f : item } if @value.is_a?(Array)
         end
       end
     end
diff --git a/lib/stack_master/sparkle_formation/compile_time/value_validator.rb b/lib/stack_master/sparkle_formation/compile_time/value_validator.rb
index a6e4f3f4..2b0e73b5 100644
--- a/lib/stack_master/sparkle_formation/compile_time/value_validator.rb
+++ b/lib/stack_master/sparkle_formation/compile_time/value_validator.rb
@@ -27,9 +27,7 @@ def build_values(definition, parameter)
         private
 
         def convert_to_array(definition, parameter)
-          if definition[:multiple] && parameter.is_a?(String)
-            return parameter.split(',').map(&:strip)
-          end
+          return parameter.split(',').map(&:strip) if definition[:multiple] && parameter.is_a?(String)
 
           parameter.is_a?(Array) ? parameter : [parameter]
         end
diff --git a/lib/stack_master/sparkle_formation/template_file.rb b/lib/stack_master/sparkle_formation/template_file.rb
index cb263ef6..f6bb232c 100644
--- a/lib/stack_master/sparkle_formation/template_file.rb
+++ b/lib/stack_master/sparkle_formation/template_file.rb
@@ -49,14 +49,14 @@ module JoinedFile
       def _joined_file(file_name, vars = {})
         join!(Template.render('joined_file', file_name, vars))
       end
-      alias_method :joined_file!, :_joined_file
+      alias joined_file! _joined_file
     end
 
     module UserDataFile
       def _user_data_file(file_name, vars = {})
         base64!(join!(Template.render('user_data', file_name, vars)))
       end
-      alias_method :user_data_file!, :_user_data_file
+      alias user_data_file! _user_data_file
     end
   end
 end
diff --git a/lib/stack_master/sso_group_id_finder.rb b/lib/stack_master/sso_group_id_finder.rb
index 9a453313..0eb71229 100644
--- a/lib/stack_master/sso_group_id_finder.rb
+++ b/lib/stack_master/sso_group_id_finder.rb
@@ -19,9 +19,9 @@ def find(reference)
             alternate_identifier: {
               unique_attribute: {
                 attribute_path: 'displayName',
-                attribute_value: match[:group_name],
-              },
-            },
+                attribute_value: match[:group_name]
+              }
+            }
           }
         )
         return response.group_id
diff --git a/lib/stack_master/stack.rb b/lib/stack_master/stack.rb
index 88e2e580..ed2f0c9f 100644
--- a/lib/stack_master/stack.rb
+++ b/lib/stack_master/stack.rb
@@ -20,9 +20,8 @@ def template_default_parameters
       TemplateUtils
         .template_hash(template)
         .fetch('Parameters', {})
-        .inject({}) do |result, (parameter_name, description)|
+        .each_with_object({}) do |(parameter_name, description), result|
           result[parameter_name] = description['Default']&.to_s
-          result
         end
     end
 
@@ -35,9 +34,8 @@ def self.find(region, stack_name)
       cf_stack = cf.describe_stacks({ stack_name: stack_name }).stacks.first
       return unless cf_stack
 
-      parameters = cf_stack.parameters.inject({}) do |params_hash, param_struct|
+      parameters = cf_stack.parameters.each_with_object({}) do |param_struct, params_hash|
         params_hash[param_struct.parameter_key] = param_struct.parameter_value
-        params_hash
       end
       template_body ||= cf.get_template({ stack_name: stack_name, template_stage: 'Original' }).template_body
       template_format = TemplateUtils.identify_template_format(template_body)
diff --git a/lib/stack_master/stack_definition.rb b/lib/stack_master/stack_definition.rb
index a71e8b96..ef750186 100644
--- a/lib/stack_master/stack_definition.rb
+++ b/lib/stack_master/stack_definition.rb
@@ -35,7 +35,7 @@ def initialize(attributes = {})
       @compiler = nil
       super
       @additional_parameter_lookup_dirs ||= []
-      @base_dir ||= ""
+      @base_dir ||= ''
       @template_dir ||= File.join(@base_dir, 'templates')
       @parameters_dir ||= File.join(@base_dir, 'parameters')
       @allowed_accounts = Array(@allowed_accounts)
@@ -44,7 +44,7 @@ def initialize(attributes = {})
     end
 
     def ==(other)
-      self.class === other &&
+      other.is_a?(self.class) &&
         @region == other.region &&
         @stack_name == other.stack_name &&
         @template == other.template &&
@@ -74,13 +74,12 @@ def files_dir
     end
 
     def s3_files
-      files.inject({}) do |hash, file|
+      files.each_with_object({}) do |file, hash|
         path = File.join(files_dir, file)
         hash[file] = {
           path: path,
           body: File.read(path)
         }
-        hash
       end
     end
 
diff --git a/lib/stack_master/stack_differ.rb b/lib/stack_master/stack_differ.rb
index 916f6edd..c868905b 100644
--- a/lib/stack_master/stack_differ.rb
+++ b/lib/stack_master/stack_differ.rb
@@ -1,5 +1,5 @@
-require "diffy"
-require "hashdiff"
+require 'diffy'
+require 'hashdiff'
 
 module StackMaster
   class StackDiffer
@@ -34,7 +34,7 @@ def proposed_parameters
       params = @proposed_stack.parameters_with_defaults
       if @current_stack
         noecho_keys.each do |key|
-          params[key] = "****"
+          params[key] = '****'
         end
       end
       YAML.dump(sort_params(params))
@@ -65,16 +65,14 @@ def output_diff
       body_diff.display
       parameters_diff.display
 
-      unless noecho_keys.empty?
-        StackMaster.stdout.puts " * can not tell if NoEcho parameters are different."
-      end
-      StackMaster.stdout.puts "No stack found" if @current_stack.nil?
+      StackMaster.stdout.puts ' * can not tell if NoEcho parameters are different.' unless noecho_keys.empty?
+      StackMaster.stdout.puts 'No stack found' if @current_stack.nil?
     end
 
     def noecho_keys
       if @current_stack
         @current_stack.parameters_with_defaults.select do |key, value|
-          value == "****"
+          value == '****'
         end.keys
       else
         []
@@ -88,7 +86,7 @@ def single_param_update?(param_name)
       return false if differences.count != 1
 
       diff = differences[0]
-      diff[0] == "~" && diff[1] == param_name
+      diff[0] == '~' && diff[1] == param_name
     end
 
     private
diff --git a/lib/stack_master/template_compilers/json.rb b/lib/stack_master/template_compilers/json.rb
index c15c41b4..4e4fcc3e 100644
--- a/lib/stack_master/template_compilers/json.rb
+++ b/lib/stack_master/template_compilers/json.rb
@@ -1,6 +1,6 @@
 module StackMaster::TemplateCompilers
   class Json
-    MAX_TEMPLATE_SIZE = 51200
+    MAX_TEMPLATE_SIZE = 51_200
     private_constant :MAX_TEMPLATE_SIZE
 
     def self.require_dependencies
diff --git a/lib/stack_master/template_compilers/sparkle_formation.rb b/lib/stack_master/template_compilers/sparkle_formation.rb
index 334bd238..40da8900 100644
--- a/lib/stack_master/template_compilers/sparkle_formation.rb
+++ b/lib/stack_master/template_compilers/sparkle_formation.rb
@@ -36,13 +36,13 @@ def self.compile_sparkle_template(template_dir, template, compiler_options)
 
       collection = ::SparkleFormation::SparkleCollection.new
       root_pack = ::SparkleFormation::Sparkle.new(
-        :root => sparkle_path,
+        root: sparkle_path
       )
       collection.set_root(root_pack)
       if compiler_options['sparkle_packs']
         compiler_options['sparkle_packs'].each do |pack_name|
           require pack_name
-          pack = ::SparkleFormation::SparklePack.new(:name => pack_name)
+          pack = ::SparkleFormation::SparklePack.new(name: pack_name)
           collection.add_sparkle(pack)
         end
       end
diff --git a/lib/stack_master/template_utils.rb b/lib/stack_master/template_utils.rb
index 37f5392d..5e120393 100644
--- a/lib/stack_master/template_utils.rb
+++ b/lib/stack_master/template_utils.rb
@@ -1,7 +1,7 @@
 module StackMaster
   module TemplateUtils
-    MAX_TEMPLATE_SIZE = 51200
-    MAX_S3_TEMPLATE_SIZE = 460800
+    MAX_TEMPLATE_SIZE = 51_200
+    MAX_S3_TEMPLATE_SIZE = 460_800
     # Matches if the first non-whitespace character is a '{', handling cases
     # with leading whitespace and extra (whitespace-only) lines.
     JSON_IDENTIFICATION_PATTERN = Regexp.new('\A\s*{', Regexp::MULTILINE)
diff --git a/lib/stack_master/test_driver/cloud_formation.rb b/lib/stack_master/test_driver/cloud_formation.rb
index dd5cf8fd..940b6efd 100644
--- a/lib/stack_master/test_driver/cloud_formation.rb
+++ b/lib/stack_master/test_driver/cloud_formation.rb
@@ -139,11 +139,11 @@ def describe_stacks(options = {})
         stack_name = options[:stack_name]
         stacks =
           if stack_name
-            if @stacks[stack_name]
-              [@stacks[stack_name]]
-            else
+            unless @stacks[stack_name]
               raise Aws::CloudFormation::Errors::ValidationError.new('', 'Stack does not exist')
             end
+
+            [@stacks[stack_name]]
           else
             @stacks.values
           end
diff --git a/lib/stack_master/test_driver/s3.rb b/lib/stack_master/test_driver/s3.rb
index ad4eda53..857f60e4 100644
--- a/lib/stack_master/test_driver/s3.rb
+++ b/lib/stack_master/test_driver/s3.rb
@@ -5,11 +5,10 @@ def initialize
         reset
       end
 
-      def set_region(_)
-      end
+      def set_region(_); end
 
       def reset
-        @files = Hash.new { |hash, key| hash[key] = Hash.new }
+        @files = Hash.new { |hash, key| hash[key] = {} }
       end
 
       def upload_files(bucket: nil, prefix: nil, region: nil, files: {})
diff --git a/lib/stack_master/utils.rb b/lib/stack_master/utils.rb
index 07173421..9a8aa9b2 100644
--- a/lib/stack_master/utils.rb
+++ b/lib/stack_master/utils.rb
@@ -22,18 +22,16 @@ def change_extension(file_name, extension)
     end
 
     def hash_to_aws_parameters(params)
-      params.inject([]) do |params, (key, value)|
+      params.each_with_object([]) do |(key, value), params|
         params << { parameter_key: key, parameter_value: value }
-        params
       end
     end
 
     def hash_to_aws_tags(tags)
       return [] if tags.nil?
 
-      tags.inject([]) do |aws_tags, (key, value)|
+      tags.each_with_object([]) do |(key, value), aws_tags|
         aws_tags << { key: key, value: value }
-        aws_tags
       end
     end
 
@@ -42,9 +40,8 @@ def underscore_to_hyphen(string)
     end
 
     def underscore_keys_to_hyphen(hash)
-      hash.inject({}) do |hash, (key, value)|
+      hash.each_with_object({}) do |(key, value), hash|
         hash[underscore_to_hyphen(key)] = value
-        hash
       end
     end
   end
diff --git a/lib/stack_master/validator.rb b/lib/stack_master/validator.rb
index 07189644..d48c7515 100644
--- a/lib/stack_master/validator.rb
+++ b/lib/stack_master/validator.rb
@@ -17,7 +17,7 @@ def perform
         return false
       end
       cf.validate_template(template_body: TemplateUtils.maybe_compressed_template_body(stack.template_body))
-      StackMaster.stdout.puts "valid"
+      StackMaster.stdout.puts 'valid'
       true
     rescue Aws::CloudFormation::Errors::ValidationError => e
       StackMaster.stdout.puts "invalid. #{e.message}"
diff --git a/lib/stack_master/version.rb b/lib/stack_master/version.rb
index 81a1d5b5..1b60eb38 100644
--- a/lib/stack_master/version.rb
+++ b/lib/stack_master/version.rb
@@ -1,3 +1,3 @@
 module StackMaster
-  VERSION = "2.17.1"
+  VERSION = '2.17.1'
 end
diff --git a/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/dynamics/my_dynamic.rb b/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/dynamics/my_dynamic.rb
index b0c896ca..329fc441 100644
--- a/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/dynamics/my_dynamic.rb
+++ b/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/dynamics/my_dynamic.rb
@@ -1,5 +1,5 @@
 SparkleFormation.dynamic(:my_dynamic) do
   outputs.foo do
-    value "bar"
+    value 'bar'
   end
 end
diff --git a/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates/dynamics/local_dynamic.rb b/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates/dynamics/local_dynamic.rb
index d5f6a558..903a4bf2 100644
--- a/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates/dynamics/local_dynamic.rb
+++ b/spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates/dynamics/local_dynamic.rb
@@ -1,5 +1,5 @@
 SparkleFormation.dynamic(:local_dynamic) do
   outputs.bar do
-    value "local_dynamic"
+    value 'local_dynamic'
   end
 end
diff --git a/spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb b/spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb
index 83d39b16..37c795cf 100644
--- a/spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb
+++ b/spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb
@@ -1,17 +1,17 @@
-CloudFormation {
-  Description "Test"
+CloudFormation do
+  Description 'Test'
 
-  Parameter("One") {
+  Parameter('One') do
     String
-    Default "Test"
+    Default 'Test'
     MaxLength 15
-  }
+  end
 
-  Output(:One, FnBase64(Ref("One")))
+  Output(:One, FnBase64(Ref('One')))
 
-  EC2_Instance(:MyInstance) {
-    DisableApiTermination external_parameters.fetch(:DisableApiTermination, "false")
-    InstanceType external_parameters["InstanceType"]
-    ImageId "ami-12345678"
-  }
-}
+  EC2_Instance(:MyInstance) do
+    DisableApiTermination external_parameters.fetch(:DisableApiTermination, 'false')
+    InstanceType external_parameters['InstanceType']
+    ImageId 'ami-12345678'
+  end
+end
diff --git a/spec/fixtures/templates/rb/cfndsl/sample-ctp.rb b/spec/fixtures/templates/rb/cfndsl/sample-ctp.rb
index fa97240c..7e7e561d 100644
--- a/spec/fixtures/templates/rb/cfndsl/sample-ctp.rb
+++ b/spec/fixtures/templates/rb/cfndsl/sample-ctp.rb
@@ -1,16 +1,16 @@
-CloudFormation {
-  Description "Test"
+CloudFormation do
+  Description 'Test'
 
-  Parameter("One") {
+  Parameter('One') do
     String
-    Default "Test"
+    Default 'Test'
     MaxLength 15
-  }
+  end
 
-  Output(:One, FnBase64(Ref("One")))
+  Output(:One, FnBase64(Ref('One')))
 
-  EC2_Instance(:MyInstance) {
-    InstanceType external_parameters["InstanceType"]
-    ImageId "ami-12345678"
-  }
-}
+  EC2_Instance(:MyInstance) do
+    InstanceType external_parameters['InstanceType']
+    ImageId 'ami-12345678'
+  end
+end
diff --git a/spec/fixtures/templates/rb/cfndsl/sample.rb b/spec/fixtures/templates/rb/cfndsl/sample.rb
index f7664adb..89d832d3 100644
--- a/spec/fixtures/templates/rb/cfndsl/sample.rb
+++ b/spec/fixtures/templates/rb/cfndsl/sample.rb
@@ -1,15 +1,15 @@
-CloudFormation {
-  Description "Test"
+CloudFormation do
+  Description 'Test'
 
-  Parameter("One") {
+  Parameter('One') do
     String
-    Default "Test"
+    Default 'Test'
     MaxLength 15
-  }
+  end
 
-  Output(:One, FnBase64(Ref("One")))
+  Output(:One, FnBase64(Ref('One')))
 
-  EC2_Instance(:MyInstance) {
-    ImageId "ami-12345678"
-  }
-}
+  EC2_Instance(:MyInstance) do
+    ImageId 'ami-12345678'
+  end
+end
diff --git a/spec/fixtures/templates/rb/sparkle_formation/templates/template.rb b/spec/fixtures/templates/rb/sparkle_formation/templates/template.rb
index 8c281623..07f2a16e 100644
--- a/spec/fixtures/templates/rb/sparkle_formation/templates/template.rb
+++ b/spec/fixtures/templates/rb/sparkle_formation/templates/template.rb
@@ -1,5 +1,5 @@
 SparkleFormation.new(:myapp_vpc_2) do
-  description "A test VPC template"
+  description 'A test VPC template'
 
   resources.vpc do
     type 'AWS::EC2::VPC'
diff --git a/spec/integration/drift_spec.rb b/spec/integration/drift_spec.rb
index 170dcb03..a3a3bf16 100644
--- a/spec/integration/drift_spec.rb
+++ b/spec/integration/drift_spec.rb
@@ -1,11 +1,11 @@
-RSpec.describe "drift command", type: :aruba do
+RSpec.describe 'drift command', type: :aruba do
   let(:cfn) { Aws::CloudFormation::Client.new(stub_responses: true) }
   let(:expected_properties) { '{"CidrIp":"1.2.3.4/0","FromPort":80,"IpProtocol":"tcp","ToPort":80}' }
   let(:actual_properties) { '{"CidrIp":"5.6.7.8/0","FromPort":80,"IpProtocol":"tcp","ToPort":80}' }
 
   before do
     allow(Aws::CloudFormation::Client).to receive(:new).and_return(cfn)
-    write_file("stack_master.yml", <<~FILE)
+    write_file('stack_master.yml', <<~FILE)
       stacks:
         us-east-1:
           myapp-web:
@@ -15,40 +15,40 @@
 
   context 'when drifted' do
     before do
-      stub_drift_detection(stack_drift_status: "DRIFTED")
+      stub_drift_detection(stack_drift_status: 'DRIFTED')
       stub_stack_resource_drift(
-        stack_name: "myapp-web",
+        stack_name: 'myapp-web',
         stack_resource_drifts: [
-          stack_id: "1",
+          stack_id: '1',
           timestamp: Time.now,
-          stack_resource_drift_status: "MODIFIED",
-          resource_type: "AWS::EC2::SecurityGroup",
-          logical_resource_id: "SecurityGroup",
-          physical_resource_id: "sg-123456",
+          stack_resource_drift_status: 'MODIFIED',
+          resource_type: 'AWS::EC2::SecurityGroup',
+          logical_resource_id: 'SecurityGroup',
+          physical_resource_id: 'sg-123456',
           expected_properties: expected_properties,
           actual_properties: actual_properties,
           property_differences: [
             {
               difference_type: 'ADD',
               property_path: '/SecurityGroupIngress/2',
-              expected_value: "",
-              actual_value: "",
+              expected_value: '',
+              actual_value: ''
             }
           ]
         ]
       )
-      run_command_and_stop("stack_master drift us-east-1 myapp-web --trace", fail_on_error: false)
+      run_command_and_stop('stack_master drift us-east-1 myapp-web --trace', fail_on_error: false)
     end
 
-    it "exits unsuccessfully" do
+    it 'exits unsuccessfully' do
       expect(last_command_stopped).not_to be_successfully_executed
     end
 
     it 'outputs stack drift information' do
       [
-        "Drift Status: DRIFTED",
-        "MODIFIED AWS::EC2::SecurityGroup SecurityGroup sg-123456",
-        "- ADD /SecurityGroupIngress/2",
+        'Drift Status: DRIFTED',
+        'MODIFIED AWS::EC2::SecurityGroup SecurityGroup sg-123456',
+        '- ADD /SecurityGroupIngress/2',
         '\-  "CidrIp": "1.2.3.4/0",',
         '\+  "CidrIp": "5.6.7.8/0",'
       ].each do |line|
@@ -59,12 +59,12 @@
 
   context 'when not drifted' do
     before do
-      stub_drift_detection(stack_drift_status: "IN_SYNC")
+      stub_drift_detection(stack_drift_status: 'IN_SYNC')
       stub_stack_resource_drift(
-        stack_name: "myapp-web",
+        stack_name: 'myapp-web',
         stack_resource_drifts: []
       )
-      run_command_and_stop("stack_master drift us-east-1 myapp-web --trace", fail_on_error: false)
+      run_command_and_stop('stack_master drift us-east-1 myapp-web --trace', fail_on_error: false)
     end
 
     it 'exits successfully' do
@@ -73,7 +73,7 @@
 
     it 'outputs stack drift information' do
       [
-        "Drift Status: IN_SYNC",
+        'Drift Status: IN_SYNC'
       ].each do |line|
         expect(last_command_stopped).to have_output an_output_string_matching(line)
       end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 4b9c8397..f9c4c4dd 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,7 +3,7 @@
 require 'pry'
 require 'os'
 
-Dir["./spec/support/**/*.rb"].sort.each { |f| require f }
+Dir['./spec/support/**/*.rb'].sort.each { |f| require f }
 
 Aws.config[:stub_responses] = true
 # This file was generated by the `rspec --init` command. Conventionally, all
@@ -63,7 +63,7 @@
   # Allows RSpec to persist some state between runs in order to support
   # the `--only-failures` and `--next-failure` CLI options. We recommend
   # you configure your source control system to ignore this file.
-  config.example_status_persistence_file_path = "spec/examples.txt"
+  config.example_status_persistence_file_path = 'spec/examples.txt'
 
   # Limits the available syntax to the non-monkey patched syntax that is
   # recommended. For more details, see:
diff --git a/spec/stack_master/aws_driver/s3_spec.rb b/spec/stack_master/aws_driver/s3_spec.rb
index bd64b8bb..b5171c86 100644
--- a/spec/stack_master/aws_driver/s3_spec.rb
+++ b/spec/stack_master/aws_driver/s3_spec.rb
@@ -44,7 +44,7 @@
             key: 'prefix/template',
             body: 'file content',
             metadata: {
-              md5: "d10b4c3ff123b26dc068d43a8bef2d23"
+              md5: 'd10b4c3ff123b26dc068d43a8bef2d23'
             }
           }
         )
@@ -58,8 +58,8 @@
           bucket: 'bucket',
           region: 'region',
           files: { 'template' => {
-            :path => 'spec/fixtures/templates/myapp_vpc.json',
-            :body => 'file content'
+            path: 'spec/fixtures/templates/myapp_vpc.json',
+            body: 'file content'
           } }
         }
       end
@@ -71,7 +71,7 @@
             key: 'template',
             body: 'file content',
             metadata: {
-              md5: "d10b4c3ff123b26dc068d43a8bef2d23"
+              md5: 'd10b4c3ff123b26dc068d43a8bef2d23'
             }
           }
         )
@@ -86,8 +86,8 @@
           region: 'region',
           prefix: 'prefix',
           files: { 'template' => {
-            :path => 'spec/fixtures/templates/myapp_vpc.json',
-            :body => 'file content'
+            path: 'spec/fixtures/templates/myapp_vpc.json',
+            body: 'file content'
           } }
         }
       end
@@ -99,7 +99,7 @@
             key: 'prefix/template',
             body: 'file content',
             metadata: {
-              md5: "d10b4c3ff123b26dc068d43a8bef2d23"
+              md5: 'd10b4c3ff123b26dc068d43a8bef2d23'
             }
           }
         )
@@ -114,12 +114,12 @@
           region: 'region',
           files: {
             'template1' => {
-              :path => 'spec/fixtures/templates/myapp_vpc.json',
-              :body => 'file content'
+              path: 'spec/fixtures/templates/myapp_vpc.json',
+              body: 'file content'
             },
             'template2' => {
-              :path => 'spec/fixtures/templates/myapp_vpc.json',
-              :body => 'file content'
+              path: 'spec/fixtures/templates/myapp_vpc.json',
+              body: 'file content'
             }
           }
         }
@@ -132,7 +132,7 @@
             key: 'template1',
             body: 'file content',
             metadata: {
-              md5: "d10b4c3ff123b26dc068d43a8bef2d23"
+              md5: 'd10b4c3ff123b26dc068d43a8bef2d23'
             }
           }
         )
@@ -142,7 +142,7 @@
             key: 'template2',
             body: 'file content',
             metadata: {
-              md5: "d10b4c3ff123b26dc068d43a8bef2d23"
+              md5: 'd10b4c3ff123b26dc068d43a8bef2d23'
             }
           }
         )
diff --git a/spec/stack_master/change_set_spec.rb b/spec/stack_master/change_set_spec.rb
index ec918b78..ce6fdeab 100644
--- a/spec/stack_master/change_set_spec.rb
+++ b/spec/stack_master/change_set_spec.rb
@@ -71,7 +71,7 @@
   describe '#display' do
     context 'a successful response' do
       let(:target) { OpenStruct.new(name: 'GroupDescription', attribute: 'Properties', requires_recreation: 'Always') }
-      let(:changes) {
+      let(:changes) do
         [
           OpenStruct.new(
             resource_change: OpenStruct.new(
@@ -90,8 +90,8 @@
             )
           )
         ]
-      }
-      let(:cf_response) {
+      end
+      let(:cf_response) do
         double(
           next_token: nil,
           changes: changes,
@@ -100,7 +100,7 @@
           status: 'FAILED',
           status_reason: 'No changes'
         )
-      }
+      end
       let(:io) { StringIO.new }
       subject(:change_set) { StackMaster::ChangeSet.new(cf_response) }
       let(:message) { io.string }
diff --git a/spec/stack_master/cloudformation_interpolating_eruby_spec.rb b/spec/stack_master/cloudformation_interpolating_eruby_spec.rb
index e911dd2c..60ff60de 100644
--- a/spec/stack_master/cloudformation_interpolating_eruby_spec.rb
+++ b/spec/stack_master/cloudformation_interpolating_eruby_spec.rb
@@ -16,7 +16,7 @@
             "#!/bin/bash\n",
             "\n",
             "REGION=ap-southeast-2\n",
-            "echo $REGION\n",
+            "echo $REGION\n"
           ]
         )
       end
@@ -35,7 +35,7 @@
             { 'Ref' => 'Param1' },
             ' ',
             { 'Ref' => 'Param2' },
-            "\n",
+            "\n"
           ]
         )
       end
@@ -59,7 +59,7 @@
             "#!/bin/bash\n",
             "\n",
             "REGION=ap-southeast-2\n",
-            "echo $REGION\n",
+            "echo $REGION\n"
           ]
         )
       end
diff --git a/spec/stack_master/command_spec.rb b/spec/stack_master/command_spec.rb
index 73eac0bb..d9ca21f4 100644
--- a/spec/stack_master/command_spec.rb
+++ b/spec/stack_master/command_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe StackMaster::Command do
-  let(:command_class) {
+  let(:command_class) do
     Class.new do
       include StackMaster::Command
 
@@ -17,7 +17,7 @@ def perform
         false
       end
     end
-  }
+  end
 
   context 'when failed is not called' do
     it 'is successful' do
@@ -63,8 +63,8 @@ def perform
       let(:error_proc) do
         proc do
           begin
-            raise RuntimeError, 'the cause message'
-          rescue
+            raise 'the cause message'
+          rescue StandardError
             raise StackMaster::TemplateCompiler::TemplateCompilationFailed, 'the message'
           end
         end
@@ -79,7 +79,7 @@ def perform
       before { command.instance_variable_set(:@options, spy(trace: true)) }
 
       it 'outputs the backtrace' do
-        expect { command.perform }.to output(%r{spec/stack_master/command_spec.rb:[\d]*:in }).to_stderr
+        expect { command.perform }.to output(%r{spec/stack_master/command_spec.rb:\d*:in }).to_stderr
       end
     end
 
@@ -87,7 +87,7 @@ def perform
       before { command.instance_variable_set(:@options, spy(trace: nil)) }
 
       it 'does not output the backtrace' do
-        expect { command.perform }.not_to output(%r{spec/stack_master/command_spec.rb:[\d]*:in }).to_stderr
+        expect { command.perform }.not_to output(%r{spec/stack_master/command_spec.rb:\d*:in }).to_stderr
       end
 
       it 'informs to set --trace option to see the backtrace' do
diff --git a/spec/stack_master/commands/apply_spec.rb b/spec/stack_master/commands/apply_spec.rb
index ef50fab0..9df35da9 100644
--- a/spec/stack_master/commands/apply_spec.rb
+++ b/spec/stack_master/commands/apply_spec.rb
@@ -61,7 +61,7 @@ def apply
         tags: [
           { key: 'environment', value: 'production' }
         ],
-        capabilities: ['CAPABILITY_IAM', 'CAPABILITY_NAMED_IAM', 'CAPABILITY_AUTO_EXPAND'],
+        capabilities: %w[CAPABILITY_IAM CAPABILITY_NAMED_IAM CAPABILITY_AUTO_EXPAND],
         role_arn: role_arn,
         notification_arns: [notification_arn]
       )
@@ -99,7 +99,7 @@ def apply
         stack_definition.s3 = {
           'bucket' => 'my-bucket',
           'prefix' => 'my-prefix',
-          'region' => 'us-east-1',
+          'region' => 'us-east-1'
         }
         stack_definition.template = 'my-template.rb'
         allow(s3).to receive(:list_objects).and_return([])
@@ -161,7 +161,7 @@ def apply
         allow(differ).to receive(:single_param_update?).with(yes_param).and_return(true)
       end
 
-      it "skips asking for confirmation on single param updates" do
+      it 'skips asking for confirmation on single param updates' do
         expect(StackMaster::ChangeSet).to receive(:execute).with(change_set.id, stack_name)
         StackMaster::Commands::Apply.perform(config, stack_definition, options)
       end
@@ -182,7 +182,7 @@ def apply
         tags: [
           { key: 'environment', value: 'production' }
         ],
-        capabilities: ['CAPABILITY_IAM', 'CAPABILITY_NAMED_IAM', 'CAPABILITY_AUTO_EXPAND'],
+        capabilities: %w[CAPABILITY_IAM CAPABILITY_NAMED_IAM CAPABILITY_AUTO_EXPAND],
         role_arn: role_arn,
         notification_arns: [notification_arn],
         change_set_type: 'CREATE'
@@ -200,7 +200,7 @@ def apply
           template_body: proposed_stack.template_body,
           parameters: [{ parameter_key: 'param_1', parameter_value: 'hello' }],
           tags: [{ key: 'environment', value: 'production' }],
-          capabilities: ['CAPABILITY_IAM', 'CAPABILITY_NAMED_IAM', 'CAPABILITY_AUTO_EXPAND'],
+          capabilities: %w[CAPABILITY_IAM CAPABILITY_NAMED_IAM CAPABILITY_AUTO_EXPAND],
           role_arn: role_arn,
           notification_arns: [notification_arn],
           on_failure: 'ROLLBACK'
@@ -217,7 +217,7 @@ def apply
     end
 
     context 'the stack is too large' do
-      let(:big_string) { 'x' * 60000 }
+      let(:big_string) { 'x' * 60_000 }
       let(:template_body) do
         "{\"a\":\"#{big_string}\"}"
       end
@@ -261,7 +261,7 @@ def apply
         allow(StackMaster::ChangeSet).to receive(:create).and_raise(StackMaster::CtrlC)
       end
 
-      it "deletes the stack" do
+      it 'deletes the stack' do
         expect(cf).to receive(:delete_stack).with({ stack_name: stack_name })
         expect { apply }.to raise_error(StackMaster::CtrlC)
       end
diff --git a/spec/stack_master/commands/compile_spec.rb b/spec/stack_master/commands/compile_spec.rb
index 425ba2aa..5e39200e 100644
--- a/spec/stack_master/commands/compile_spec.rb
+++ b/spec/stack_master/commands/compile_spec.rb
@@ -4,13 +4,13 @@
   let(:stack_definition) { StackMaster::StackDefinition.new(base_dir: '/base_dir', region: region, stack_name: stack_name) }
   let(:config) { double(find_stack: stack_definition) }
   let(:parameters) { {} }
-  let(:proposed_stack) {
+  let(:proposed_stack) do
     StackMaster::Stack.new(
       template_body: template_body,
       template_format: template_format,
       parameters: parameters
     )
-  }
+  end
 
   let(:template_body) { '{}' }
   let(:template_format) { :json }
@@ -23,13 +23,13 @@ def run
     described_class.perform(config, stack_definition)
   end
 
-  context "with a json stack" do
+  context 'with a json stack' do
     it 'outputs the template' do
       expect { run }.to output(template_body + "\n").to_stdout
     end
   end
 
-  context "with a yaml stack" do
+  context 'with a yaml stack' do
     let(:template_body) { '---' }
     let(:template_format) { :yaml }
 
diff --git a/spec/stack_master/commands/delete_spec.rb b/spec/stack_master/commands/delete_spec.rb
index a2868f5f..5376e307 100644
--- a/spec/stack_master/commands/delete_spec.rb
+++ b/spec/stack_master/commands/delete_spec.rb
@@ -12,8 +12,8 @@
     allow(StackMaster::StackEvents::Streamer).to receive(:stream)
   end
 
-  describe "#perform" do
-    context "The stack exists" do
+  describe '#perform' do
+    context 'The stack exists' do
       before do
         allow(cf)
           .to receive(:describe_stacks)
@@ -21,7 +21,7 @@
             {
               stacks: [
                 {
-                  stack_id: "ABC",
+                  stack_id: 'ABC',
                   stack_name: stack_name,
                   creation_time: Time.now,
                   stack_status: 'UPDATE_COMPLETE',
@@ -31,18 +31,18 @@
             }
           )
       end
-      it "deletes the stack and tails the events" do
+      it 'deletes the stack and tails the events' do
         delete.perform
-        expect(cf).to have_received(:delete_stack).with({ :stack_name => region })
+        expect(cf).to have_received(:delete_stack).with({ stack_name: region })
         expect(StackMaster::StackEvents::Streamer).to have_received(:stream)
       end
     end
 
-    context "The stack does not exist" do
+    context 'The stack does not exist' do
       before do
-        allow(cf).to receive(:describe_stacks).and_raise(Aws::CloudFormation::Errors::ValidationError.new("x", "y"))
+        allow(cf).to receive(:describe_stacks).and_raise(Aws::CloudFormation::Errors::ValidationError.new('x', 'y'))
       end
-      it "is not successful" do
+      it 'is not successful' do
         delete.perform
         expect(StackMaster::StackEvents::Streamer).not_to have_received(:stream)
         expect(cf).not_to have_received(:delete_stack)
diff --git a/spec/stack_master/commands/drift_spec.rb b/spec/stack_master/commands/drift_spec.rb
index 724fbb55..a6e25b2a 100644
--- a/spec/stack_master/commands/drift_spec.rb
+++ b/spec/stack_master/commands/drift_spec.rb
@@ -6,41 +6,41 @@
 
   subject(:drift) { described_class.new(config, stack_definition, options) }
   let(:stack_drift_detection_id) { 123 }
-  let(:detect_stack_drift_response) {
+  let(:detect_stack_drift_response) do
     Aws::CloudFormation::Types::DetectStackDriftOutput.new(
       stack_drift_detection_id: stack_drift_detection_id
     )
-  }
-  let(:stack_drift_status) { "IN_SYNC" }
-  let(:describe_stack_drift_detection_status_response) {
+  end
+  let(:stack_drift_status) { 'IN_SYNC' }
+  let(:describe_stack_drift_detection_status_response) do
     Aws::CloudFormation::Types::DescribeStackDriftDetectionStatusOutput.new(
       stack_drift_detection_id: stack_drift_detection_id,
       stack_drift_status: stack_drift_status,
-      detection_status: "DETECTION_COMPLETE"
+      detection_status: 'DETECTION_COMPLETE'
     )
-  }
-  let(:describe_stack_resource_drifts_response) {
+  end
+  let(:describe_stack_resource_drifts_response) do
     Aws::CloudFormation::Types::DescribeStackResourceDriftsOutput.new(
       stack_resource_drifts: stack_resource_drifts
     )
-  }
-  let(:property_difference) {
+  end
+  let(:property_difference) do
     Aws::CloudFormation::Types::PropertyDifference.new(
       difference_type: 'ADD',
       property_path: '/SecurityGroupIngress/2'
     )
-  }
-  let(:stack_resource_drifts) {
+  end
+  let(:stack_resource_drifts) do
     [
       Aws::CloudFormation::Types::StackResourceDrift.new(
-        stack_resource_drift_status: "IN_SYNC",
-        resource_type: "AWS::EC2::SecurityGroup",
-        logical_resource_id: "SecurityGroup",
-        physical_resource_id: "sg-123456",
+        stack_resource_drift_status: 'IN_SYNC',
+        resource_type: 'AWS::EC2::SecurityGroup',
+        logical_resource_id: 'SecurityGroup',
+        physical_resource_id: 'sg-123456',
         property_differences: [property_difference]
       )
     ]
-  }
+  end
 
   before do
     options.timeout = 10
@@ -74,33 +74,33 @@
     let(:stack_drift_status) { 'DRIFTED' }
     let(:expected_properties) { '{"CidrIp":"1.2.3.4/0","FromPort":80,"IpProtocol":"tcp","ToPort":80}' }
     let(:actual_properties) { '{"CidrIp":"5.6.7.8/0","FromPort":80,"IpProtocol":"tcp","ToPort":80}' }
-    let(:stack_resource_drifts) {
+    let(:stack_resource_drifts) do
       [
         Aws::CloudFormation::Types::StackResourceDrift.new(
-          stack_resource_drift_status: "DELETED",
-          resource_type: "AWS::EC2::SecurityGroup",
-          logical_resource_id: "SecurityGroup1",
-          physical_resource_id: "sg-123456",
+          stack_resource_drift_status: 'DELETED',
+          resource_type: 'AWS::EC2::SecurityGroup',
+          logical_resource_id: 'SecurityGroup1',
+          physical_resource_id: 'sg-123456',
           property_differences: [property_difference]
         ),
         Aws::CloudFormation::Types::StackResourceDrift.new(
-          stack_resource_drift_status: "MODIFIED",
-          resource_type: "AWS::EC2::SecurityGroup",
-          logical_resource_id: "SecurityGroup2",
-          physical_resource_id: "sg-789012",
+          stack_resource_drift_status: 'MODIFIED',
+          resource_type: 'AWS::EC2::SecurityGroup',
+          logical_resource_id: 'SecurityGroup2',
+          physical_resource_id: 'sg-789012',
           expected_properties: expected_properties,
           actual_properties: actual_properties,
           property_differences: [property_difference]
         ),
         Aws::CloudFormation::Types::StackResourceDrift.new(
-          stack_resource_drift_status: "IN_SYNC",
-          resource_type: "AWS::EC2::SecurityGroup",
-          logical_resource_id: "SecurityGroup3",
-          physical_resource_id: "sg-345678",
+          stack_resource_drift_status: 'IN_SYNC',
+          resource_type: 'AWS::EC2::SecurityGroup',
+          logical_resource_id: 'SecurityGroup3',
+          physical_resource_id: 'sg-345678',
           property_differences: [property_difference]
         )
       ]
-    }
+    end
 
     it 'outputs drift status' do
       expect { drift.perform }.to output(/Drift Status: DRIFTED/).to_stdout
diff --git a/spec/stack_master/commands/init_spec.rb b/spec/stack_master/commands/init_spec.rb
index 6b034527..e0e883d8 100644
--- a/spec/stack_master/commands/init_spec.rb
+++ b/spec/stack_master/commands/init_spec.rb
@@ -1,14 +1,14 @@
 RSpec.describe StackMaster::Commands::Init do
   subject(:init_command) { described_class.new(options, region, stack_name) }
-  let(:region) { "us-east-1" }
-  let(:stack_name) { "test-stack" }
+  let(:region) { 'us-east-1' }
+  let(:stack_name) { 'test-stack' }
   let(:options) { double(overwrite: false) }
 
-  describe "#perform" do
-    it "creates all the expected files" do
+  describe '#perform' do
+    it 'creates all the expected files' do
       expect(IO)
         .to receive(:write)
-        .with("stack_master.yml", <<~YAML)
+        .with('stack_master.yml', <<~YAML)
           stacks:
             us-east-1:
               test-stack:
@@ -19,7 +19,7 @@
 
       expect(IO)
         .to receive(:write)
-        .with("parameters/test-stack.yml", <<~YAML)
+        .with('parameters/test-stack.yml', <<~YAML)
           # Add parameters here:
           # param1: value1
           # param2: value2
@@ -27,7 +27,7 @@
 
       expect(IO)
         .to receive(:write)
-        .with("parameters/us-east-1/test-stack.yml", <<~YAML)
+        .with('parameters/us-east-1/test-stack.yml', <<~YAML)
           # Add parameters here:
           # param1: value1
           # param2: value2
@@ -35,7 +35,7 @@
 
       expect(IO)
         .to receive(:write)
-        .with("templates/test-stack.json", <<~JSON)
+        .with('templates/test-stack.json', <<~JSON)
           {
             "AWSTemplateFormatVersion" : "2010-09-09",
             "Description" : "Cloudformation stack for test-stack",
@@ -58,7 +58,7 @@
           }
         JSON
 
-      init_command.perform()
+      init_command.perform
     end
   end
 end
diff --git a/spec/stack_master/commands/lint_spec.rb b/spec/stack_master/commands/lint_spec.rb
index 399f7f0a..900ad912 100644
--- a/spec/stack_master/commands/lint_spec.rb
+++ b/spec/stack_master/commands/lint_spec.rb
@@ -4,13 +4,13 @@
   let(:stack_definition) { StackMaster::StackDefinition.new(base_dir: '/base_dir', region: region, stack_name: stack_name) }
   let(:config) { double(find_stack: stack_definition) }
   let(:parameters) { {} }
-  let(:proposed_stack) {
+  let(:proposed_stack) do
     StackMaster::Stack.new(
       template_body: template_body,
       template_format: template_format,
       parameters: parameters
     )
-  }
+  end
   let(:tempfile) { double(:tempfile) }
   let(:path) { double(:path) }
 
@@ -22,12 +22,12 @@ def run
     described_class.perform(config, stack_definition)
   end
 
-  context "when cfn-lint is installed" do
+  context 'when cfn-lint is installed' do
     before do
       expect_any_instance_of(described_class).to receive(:system).once.with('cfn-lint', '--version').and_return(0)
     end
 
-    context "with a json stack" do
+    context 'with a json stack' do
       let(:template_body) { '{}' }
       let(:template_format) { :json }
 
@@ -37,7 +37,7 @@ def run
       end
     end
 
-    context "with a yaml stack" do
+    context 'with a yaml stack' do
       let(:template_body) { '---' }
       let(:template_format) { :yaml }
 
@@ -48,7 +48,7 @@ def run
     end
   end
 
-  context "when cfn-lint is missing" do
+  context 'when cfn-lint is missing' do
     let(:template_body) { '' }
     let(:template_format) { :json }
 
diff --git a/spec/stack_master/commands/nag_spec.rb b/spec/stack_master/commands/nag_spec.rb
index a7854bc5..55408340 100644
--- a/spec/stack_master/commands/nag_spec.rb
+++ b/spec/stack_master/commands/nag_spec.rb
@@ -4,13 +4,13 @@
   let(:stack_definition) { StackMaster::StackDefinition.new(base_dir: '/base_dir', region: region, stack_name: stack_name) }
   let(:config) { instance_double(StackMaster::Config, find_stack: stack_definition) }
   let(:parameters) { {} }
-  let(:proposed_stack) {
+  let(:proposed_stack) do
     StackMaster::Stack.new(
       template_body: template_body,
       template_format: template_format,
       parameters: parameters
     )
-  }
+  end
   let(:tempfile) { double(Tempfile) }
   let(:path) { double(String) }
   let(:template_body) { '{}' }
@@ -26,7 +26,7 @@ def run
     described_class.perform(config, stack_definition)
   end
 
-  context "with a json stack" do
+  context 'with a json stack' do
     it 'calls the nag gem' do
       expect_any_instance_of(File).to receive(:write).once
       expect_any_instance_of(File).to receive(:flush).once
@@ -35,7 +35,7 @@ def run
     end
   end
 
-  context "with a yaml stack" do
+  context 'with a yaml stack' do
     let(:template_body) { '---' }
     let(:template_format) { :yaml }
 
@@ -47,7 +47,7 @@ def run
     end
   end
 
-  context "when check is successful" do
+  context 'when check is successful' do
     it 'exits with a zero exit status' do
       expect_any_instance_of(described_class).to receive(:system).once.with('cfn_nag', /.*\.json/)
       result = run
@@ -55,7 +55,7 @@ def run
     end
   end
 
-  context "when check fails" do
+  context 'when check fails' do
     let(:exitstatus) { 1 }
     it 'exits with non-zero exit status' do
       expect_any_instance_of(described_class).to receive(:system).once.with('cfn_nag', /.*\.json/)
diff --git a/spec/stack_master/commands/status_spec.rb b/spec/stack_master/commands/status_spec.rb
index 3268ba43..bee3d8c8 100644
--- a/spec/stack_master/commands/status_spec.rb
+++ b/spec/stack_master/commands/status_spec.rb
@@ -23,13 +23,13 @@
     allow(Aws::CloudFormation::Client).to receive(:new).with(region: 'us-east-1').and_return cf
   end
 
-  context "#perform" do
+  context '#perform' do
     before do
       allow(StackMaster::Stack).to receive(:find).and_return stack1, stack2
       allow(StackMaster::Stack).to receive(:generate).and_return proposed_stack1, proposed_stack2
     end
 
-    context "some parameters are different" do
+    context 'some parameters are different' do
       let(:stack1) do
         double(
           :stack1,
@@ -53,14 +53,14 @@
       end
 
       let(:proposed_stack1) do
-        double(:proposed_stack1, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack1, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
       let(:proposed_stack2) do
-        double(:proposed_stack2, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack2, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
-      it "returns the status of call stacks" do
+      it 'returns the status of call stacks' do
         out = <<~OUTPUT
           REGION    | STACK_NAME | STACK_STATUS    | DIFFERENT
           ----------|------------|-----------------|----------
@@ -72,7 +72,7 @@
       end
     end
 
-    context "some templates are different" do
+    context 'some templates are different' do
       let(:stack1) do
         double(
           :stack1,
@@ -96,14 +96,14 @@
       end
 
       let(:proposed_stack1) do
-        double(:proposed_stack1, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack1, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
       let(:proposed_stack2) do
-        double(:proposed_stack2, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack2, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
-      it "returns the status of call stacks" do
+      it 'returns the status of call stacks' do
         out = <<~OUTPUT
           REGION    | STACK_NAME | STACK_STATUS    | DIFFERENT
           ----------|------------|-----------------|----------
@@ -145,11 +145,11 @@
       end
 
       let(:proposed_stack1) do
-        double(:proposed_stack1, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack1, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
       let(:proposed_stack2) do
-        double(:proposed_stack2, template_body: "{}", template_format: :json, parameters_with_defaults: { a: 1 })
+        double(:proposed_stack2, template_body: '{}', template_format: :json, parameters_with_defaults: { a: 1 })
       end
 
       before do
@@ -184,7 +184,7 @@
           StackMaster.reset_flags
         end
 
-        it "returns the status of call stacks" do
+        it 'returns the status of call stacks' do
           out = <<~OUTPUT
             REGION    | STACK_NAME | STACK_STATUS    | DIFFERENT
             ----------|------------|-----------------|----------
diff --git a/spec/stack_master/commands/validate_spec.rb b/spec/stack_master/commands/validate_spec.rb
index 697af6fb..dc763f82 100644
--- a/spec/stack_master/commands/validate_spec.rb
+++ b/spec/stack_master/commands/validate_spec.rb
@@ -1,8 +1,8 @@
 RSpec.describe StackMaster::Commands::Validate do
   subject(:validate) { described_class.new(config, stack_definition, options) }
   let(:config) { instance_double(StackMaster::Config) }
-  let(:region) { "us-east-1" }
-  let(:stack_name) { "mystack" }
+  let(:region) { 'us-east-1' }
+  let(:stack_name) { 'mystack' }
   let(:options) { Commander::Command::Options.new }
   let(:stack_definition) do
     StackMaster::StackDefinition.new(
@@ -14,9 +14,9 @@
     )
   end
 
-  describe "#perform" do
-    context "can find stack" do
-      it "calls the validator to validate the stack definition" do
+  describe '#perform' do
+    context 'can find stack' do
+      it 'calls the validator to validate the stack definition' do
         expect(StackMaster::Validator).to receive(:valid?).with(stack_definition, config, options)
         validate.perform
       end
diff --git a/spec/stack_master/config_spec.rb b/spec/stack_master/config_spec.rb
index 6a866847..548fbf07 100644
--- a/spec/stack_master/config_spec.rb
+++ b/spec/stack_master/config_spec.rb
@@ -1,30 +1,30 @@
 RSpec.describe StackMaster::Config do
   subject(:loaded_config) { StackMaster::Config.load!('spec/fixtures/stack_master.yml') }
   let(:base_dir) { File.expand_path('spec/fixtures') }
-  let(:myapp_vpc_definition) {
+  let(:myapp_vpc_definition) do
     StackMaster::StackDefinition.new(
       region: 'us-east-1',
       region_alias: 'production',
       stack_name: 'myapp-vpc',
       template: 'myapp_vpc.json',
-      allowed_accounts: ["555555555"],
+      allowed_accounts: ['555555555'],
       tags: { 'application' => 'my-awesome-blog', 'environment' => 'production' },
       s3: { 'bucket' => 'my-bucket', 'region' => 'us-east-1' },
-      notification_arns: ['test_arn', 'test_arn_2'],
+      notification_arns: %w[test_arn test_arn_2],
       role_arn: 'test_service_role_arn2',
       base_dir: base_dir,
       stack_policy_file: 'my_policy.json',
       additional_parameter_lookup_dirs: ['production']
     )
-  }
+  end
   let(:bad_yaml) { "a: b\n- c" }
 
-  describe ".load!" do
-    it "fails to load the config if no stack_master.yml in parent directories" do
+  describe '.load!' do
+    it 'fails to load the config if no stack_master.yml in parent directories' do
       expect { StackMaster::Config.load!('stack_master.yml') }.to raise_error Errno::ENOENT
     end
 
-    it "raises exception on invalid yaml" do
+    it 'raises exception on invalid yaml' do
       begin
         orig_dir = Dir.pwd
         Dir.chdir './spec/fixtures/'
@@ -35,21 +35,21 @@
       end
     end
 
-    it "gives explicit error on badly indented entries" do
+    it 'gives explicit error on badly indented entries' do
       Dir.chdir('./spec/fixtures/') do
         expect { StackMaster::Config.load!('stack_master_wrong_indent.yml') }
           .to raise_error StackMaster::Config::ConfigParseError
       end
     end
 
-    it "gives explicit error on empty defaults" do
+    it 'gives explicit error on empty defaults' do
       Dir.chdir('./spec/fixtures/') do
         expect { StackMaster::Config.load!('stack_master_empty_default.yml') }
           .to raise_error StackMaster::Config::ConfigParseError
       end
     end
 
-    it "searches up the tree for stack master yaml" do
+    it 'searches up the tree for stack master yaml' do
       begin
         orig_dir = Dir.pwd
         Dir.chdir './spec/fixtures/templates'
@@ -97,7 +97,7 @@
     expect(loaded_config.stack_defaults)
       .to eq(
         {
-          'allowed_accounts' => ["555555555"],
+          'allowed_accounts' => ['555555555'],
           'tags' => { 'application' => 'my-awesome-blog' },
           's3' => { 'bucket' => 'my-bucket', 'region' => 'us-east-1' }
         }
@@ -112,7 +112,7 @@
           json: :json,
           yml: :yaml,
           yaml: :yaml,
-          erb: :yaml_erb,
+          erb: :yaml_erb
         }
       )
   end
@@ -130,7 +130,7 @@
           'ap-southeast-2' => {
             'tags' => { 'environment' => 'staging', 'test_override' => 1 },
             'role_arn' => 'test_service_role_arn3',
-            'notification_arns' => ['test_arn_3'],
+            'notification_arns' => ['test_arn_3']
           }
         }
       )
@@ -150,11 +150,11 @@
           stack_name: 'myapp-vpc',
           region: 'ap-southeast-2',
           region_alias: 'staging',
-          allowed_accounts: ["555555555"],
+          allowed_accounts: ['555555555'],
           tags: { 'application' => 'my-awesome-blog', 'environment' => 'staging', 'test_override' => 1 },
           s3: { 'bucket' => 'my-bucket', 'region' => 'us-east-1' },
           role_arn: 'test_service_role_arn4',
-          notification_arns: ['test_arn_3', 'test_arn_4'],
+          notification_arns: %w[test_arn_3 test_arn_4],
           template: 'myapp_vpc.rb',
           base_dir: base_dir,
           additional_parameter_lookup_dirs: ['staging']
@@ -166,7 +166,7 @@
           stack_name: 'myapp-web',
           region: 'ap-southeast-2',
           region_alias: 'staging',
-          allowed_accounts: ["1234567890", "9876543210"],
+          allowed_accounts: %w[1234567890 9876543210],
           tags: { 'application' => 'my-awesome-blog', 'environment' => 'staging', 'test_override' => 2 },
           s3: { 'bucket' => 'my-bucket', 'region' => 'us-east-1' },
           role_arn: 'test_service_role_arn3',
diff --git a/spec/stack_master/identity_spec.rb b/spec/stack_master/identity_spec.rb
index c1df0fdd..82928fb0 100644
--- a/spec/stack_master/identity_spec.rb
+++ b/spec/stack_master/identity_spec.rb
@@ -97,7 +97,7 @@
       end
 
       context 'with a combination of account id and alias' do
-        let(:allowed_accounts) { %w(192837471659 allowed-account another-account) }
+        let(:allowed_accounts) { %w[192837471659 allowed-account another-account] }
 
         it 'returns true' do
           expect(running_in_allowed_account).to eq(true)
@@ -148,14 +148,14 @@
       iam.stub_responses(
         :list_account_aliases,
         {
-          account_aliases: %w(my-account new-account-name),
+          account_aliases: %w[my-account new-account-name],
           is_truncated: false
         }
       )
     end
 
     it 'returns the current identity account aliases' do
-      expect(identity.account_aliases).to eq(%w(my-account new-account-name))
+      expect(identity.account_aliases).to eq(%w[my-account new-account-name])
     end
 
     context "when identity doesn't have the required iam permissions" do
diff --git a/spec/stack_master/paged_response_accumulator_spec.rb b/spec/stack_master/paged_response_accumulator_spec.rb
index 7d65aeb9..606e278a 100644
--- a/spec/stack_master/paged_response_accumulator_spec.rb
+++ b/spec/stack_master/paged_response_accumulator_spec.rb
@@ -3,12 +3,12 @@
   subject(:accumulator) { described_class.new(cf, :describe_stack_events, { stack_name: 'blah' }, :stack_events) }
 
   context 'with one page' do
-    let(:page_one_events) {
+    let(:page_one_events) do
       [
         { event_id: '1', stack_id: '1', stack_name: 'blah', timestamp: Time.now },
         { event_id: '2', stack_id: '1', stack_name: 'blah', timestamp: Time.now }
       ]
-    }
+    end
 
     before do
       cf.stub_responses(:describe_stack_events, { stack_events: page_one_events, next_token: nil })
@@ -21,17 +21,17 @@
   end
 
   context 'with two pages' do
-    let(:page_one_events) {
+    let(:page_one_events) do
       [
         { event_id: '1', stack_id: '1', stack_name: 'blah', timestamp: Time.now },
         { event_id: '2', stack_id: '1', stack_name: 'blah', timestamp: Time.now }
       ]
-    }
-    let(:page_two_events) {
+    end
+    let(:page_two_events) do
       [
         { event_id: '3', stack_id: '1', stack_name: 'blah', timestamp: Time.now }
       ]
-    }
+    end
 
     before do
       cf.stub_responses(
diff --git a/spec/stack_master/parameter_loader_spec.rb b/spec/stack_master/parameter_loader_spec.rb
index aa6bfd9d..719a71b3 100644
--- a/spec/stack_master/parameter_loader_spec.rb
+++ b/spec/stack_master/parameter_loader_spec.rb
@@ -57,9 +57,9 @@
 
   context 'yml and yaml region parameter files' do
     let(:stack_file_returns) { { exists: false } }
-    let(:region_file_returns) { { exists: true, read: "Param2: value2" } }
+    let(:region_file_returns) { { exists: true, read: 'Param2: value2' } }
     let(:region_yaml_file_returns) { { exists: true, read: "Param1: value1\nParam2: valueX" } }
-    let(:region_yaml_file_name) { "/base_dir/parameters/us-east-1/stack_name.yaml" }
+    let(:region_yaml_file_name) { '/base_dir/parameters/us-east-1/stack_name.yaml' }
 
     subject(:parameters) { StackMaster::ParameterLoader.load(parameter_files: [stack_file_name, region_yaml_file_name, region_file_name]) }
 
diff --git a/spec/stack_master/parameter_resolver_spec.rb b/spec/stack_master/parameter_resolver_spec.rb
index 363b6f13..fa9cc3e4 100644
--- a/spec/stack_master/parameter_resolver_spec.rb
+++ b/spec/stack_master/parameter_resolver_spec.rb
@@ -7,26 +7,24 @@
   end
   let(:config) { double }
   let(:region) { 'us-east-1' }
-  let(:my_resolver) {
+  let(:my_resolver) do
     Class.new do
-      def initialize(config, region)
-      end
+      def initialize(config, region); end
 
       def resolve(value)
         value.to_i * 5
       end
     end
-  }
-  let(:bad_resolver) {
+  end
+  let(:bad_resolver) do
     Class.new do
-      def initialize(config, region)
-      end
+      def initialize(config, region); end
 
       def resolve(value)
         raise Aws::CloudFormation::Errors::ValidationError.new(nil, "Can't find stack")
       end
     end
-  }
+  end
 
   before do
     stub_const('StackMaster::ParameterResolvers::MyResolver', my_resolver)
@@ -55,15 +53,15 @@ def resolve(params)
   end
 
   it 'it throws an error when the hash contains more than one key' do
-    expect {
+    expect do
       resolve(param: { nested1: 'value1', nested2: 'value2' })
-    }.to raise_error(StackMaster::ParameterResolver::InvalidParameter)
+    end.to raise_error(StackMaster::ParameterResolver::InvalidParameter)
   end
 
   it "doesn't throw an error when given an array" do
-    expect {
+    expect do
       resolve(param: [1, 2])
-    }.to_not raise_error
+    end.to_not raise_error
   end
 
   context 'when array values contain resolver hashes' do
@@ -84,17 +82,17 @@ def resolve(params)
 
   context 'when the resolver is unknown' do
     it 'throws an error' do
-      expect {
+      expect do
         resolve(param: { my_unknown_resolver: 2 })
-      }.to raise_error StackMaster::ParameterResolver::ResolverNotFound
+      end.to raise_error StackMaster::ParameterResolver::ResolverNotFound
     end
   end
 
   context 'when the resolver throws a ValidationError' do
     it 'throws a invalid parameter error' do
-      expect {
+      expect do
         resolve(param: { bad_resolver: 2 })
-      }.to raise_error StackMaster::ParameterResolver::InvalidParameter
+      end.to raise_error StackMaster::ParameterResolver::InvalidParameter
     end
   end
 
@@ -166,25 +164,25 @@ def resolve(params)
 
     context "with missing 'account' property" do
       it 'raises an invalid parameter error' do
-        expect {
+        expect do
           resolve(param: { 'role' => role, 'my_resolver' => 2 })
-        }.to raise_error StackMaster::ParameterResolver::InvalidParameter,
-                         match("Both 'account' and 'role' are required to assume role for parameter 'param'")
+        end.to raise_error StackMaster::ParameterResolver::InvalidParameter,
+                           match("Both 'account' and 'role' are required to assume role for parameter 'param'")
       end
     end
 
     context "with missing 'role' property" do
       it 'raises an invalid parameter error' do
-        expect {
+        expect do
           resolve(param: { 'account' => account, 'my_resolver' => 2 })
-        }.to raise_error StackMaster::ParameterResolver::InvalidParameter,
-                         match("Both 'account' and 'role' are required to assume role for parameter 'param'")
+        end.to raise_error StackMaster::ParameterResolver::InvalidParameter,
+                           match("Both 'account' and 'role' are required to assume role for parameter 'param'")
       end
     end
   end
 
   context 'resolver class caching' do
-    it "uses the same instance of the resolver for the duration of the resolve run" do
+    it 'uses the same instance of the resolver for the duration of the resolve run' do
       expect(my_resolver).to receive(:new).once.and_call_original
       expect(resolve(param: { my_resolver: 2 }, param2: { my_resolver: 2 })).to eq(param: 10, param2: 10)
     end
@@ -214,23 +212,23 @@ def resolve(params)
       parameter_resolver.resolve
     end
 
-    context "using an array resolver" do
+    context 'using an array resolver' do
       let(:params) do
         {
           param: { other_dummy_resolvers: [1, 2] }
         }
       end
 
-      it "tries to load the plural and singular forms" do
+      it 'tries to load the plural and singular forms' do
         expect(parameter_resolver)
           .to receive(:require_parameter_resolver)
-          .with("other_dummy_resolvers")
+          .with('other_dummy_resolvers')
           .once
           .and_call_original
           .ordered
         expect(parameter_resolver)
           .to receive(:require_parameter_resolver)
-          .with("other_dummy_resolver")
+          .with('other_dummy_resolver')
           .once
           .ordered
         expect(parameter_resolver)
diff --git a/spec/stack_master/parameter_resolvers/ami_finder_spec.rb b/spec/stack_master/parameter_resolvers/ami_finder_spec.rb
index b03bdc5b..5e57f116 100644
--- a/spec/stack_master/parameter_resolvers/ami_finder_spec.rb
+++ b/spec/stack_master/parameter_resolvers/ami_finder_spec.rb
@@ -40,7 +40,7 @@
   end
 
   describe '#find_latest_ami' do
-    let(:filter) { [{ name: "String", values: ["String"] }] }
+    let(:filter) { [{ name: 'String', values: ['String'] }] }
 
     context 'when matches are found' do
       before do
diff --git a/spec/stack_master/parameter_resolvers/ejson_spec.rb b/spec/stack_master/parameter_resolvers/ejson_spec.rb
index 855400b7..7c1447ef 100644
--- a/spec/stack_master/parameter_resolvers/ejson_spec.rb
+++ b/spec/stack_master/parameter_resolvers/ejson_spec.rb
@@ -69,12 +69,12 @@
     end
   end
 
-  context "when different credentials are used" do
+  context 'when different credentials are used' do
     it 'caches the decrypted file by credentials' do
       expect(EJSONWrapper).to receive(:decrypt).twice
       ejson.resolve('secret_a')
       ejson.resolve('secret_b')
-      Aws.config[:credentials] = "my-credentials"
+      Aws.config[:credentials] = 'my-credentials'
       ejson.resolve('secret_a')
       ejson.resolve('secret_b')
       Aws.config.delete(:credentials)
diff --git a/spec/stack_master/parameter_resolvers/latest_ami_spec.rb b/spec/stack_master/parameter_resolvers/latest_ami_spec.rb
index 3603ea6c..77b0a929 100644
--- a/spec/stack_master/parameter_resolvers/latest_ami_spec.rb
+++ b/spec/stack_master/parameter_resolvers/latest_ami_spec.rb
@@ -45,7 +45,7 @@
 
     it 'calls find_latest_ami with the owner and filters' do
       expect(ami_finder).to receive(:find_latest_ami).with([{ name: 'foo', values: ['bacon'] }], ['123456'])
-      resolver.resolve({ 'owners' => 123456, 'filters' => { 'foo' => 'bacon' } })
+      resolver.resolve({ 'owners' => 123_456, 'filters' => { 'foo' => 'bacon' } })
     end
   end
 end
diff --git a/spec/stack_master/parameter_resolvers/latest_container_spec.rb b/spec/stack_master/parameter_resolvers/latest_container_spec.rb
index c2a8dd37..fe20d4dc 100644
--- a/spec/stack_master/parameter_resolvers/latest_container_spec.rb
+++ b/spec/stack_master/parameter_resolvers/latest_container_spec.rb
@@ -59,7 +59,7 @@
               registry_id: '012345678910',
               image_digest: 'sha256:decafc0ffee',
               image_pushed_at: Time.utc(2015, 1, 2, 0, 0),
-              image_tags: ['v1', 'production']
+              image_tags: %w[v1 production]
             },
             {
               registry_id: '012345678910',
@@ -99,7 +99,7 @@
               image_digest: 'sha256:decafc0ffee',
               image_pushed_at: Time.utc(2015, 1, 2, 0, 0),
               image_tags: ['v1']
-            },
+            }
           ]
         }
       )
@@ -110,10 +110,10 @@
         .to receive(:describe_images)
         .with(
           {
-            repository_name: "foo",
-            registry_id: "012345678910",
+            repository_name: 'foo',
+            registry_id: '012345678910',
             next_token: nil,
-            filter: { :tag_status => "TAGGED" }
+            filter: { tag_status: 'TAGGED' }
           }
         )
       resolver.resolve({ 'repository_name' => 'foo', 'registry_id' => '012345678910' })
@@ -137,7 +137,7 @@
                 registry_id: '012345678910',
                 image_digest: 'sha256:deadbeef',
                 image_pushed_at: Time.utc(2015, 1, 3, 0, 0),
-                image_tags: ['latest', 'v2']
+                image_tags: %w[latest v2]
               }
             ]
           },
diff --git a/spec/stack_master/parameter_resolvers/one_password_spec.rb b/spec/stack_master/parameter_resolvers/one_password_spec.rb
index 40703a9e..3fac18e1 100644
--- a/spec/stack_master/parameter_resolvers/one_password_spec.rb
+++ b/spec/stack_master/parameter_resolvers/one_password_spec.rb
@@ -4,105 +4,105 @@
     let(:stack_definition) { double(stack_name: 'mystack', region: 'us-east-1') }
     subject(:resolver) { described_class.new(config, stack_definition) }
     let(:op_env_unset) { ENV['OP_SESSION_something'].clear }
-    let(:secureNote) {
+    let(:secureNote) do
       {
-        "uuid" => "auuid",
-        "vaultUuid" => "avaultuuid",
-        "templateUuid" => "003",
-        "createdAt" => "2018-01-17 07:28:11 +0000 UTC",
-        "updatedAt" => "2018-01-17 07:28:11 +0000 UTC",
-        "changerUuid" => "anotheruuid",
-        "overview" => {
-          "ainfo" => "begin message",
-          "ps" => 0,
-          "title" => "note title"
+        'uuid' => 'auuid',
+        'vaultUuid' => 'avaultuuid',
+        'templateUuid' => '003',
+        'createdAt' => '2018-01-17 07:28:11 +0000 UTC',
+        'updatedAt' => '2018-01-17 07:28:11 +0000 UTC',
+        'changerUuid' => 'anotheruuid',
+        'overview' => {
+          'ainfo' => 'begin message',
+          'ps' => 0,
+          'title' => 'note title'
         },
-        "details" => {
-          "notesPlain" => "decrypted note",
-          "sections" => [
+        'details' => {
+          'notesPlain' => 'decrypted note',
+          'sections' => [
             {
-              "name" => "linked items",
-              "title" => "Related Items"
+              'name' => 'linked items',
+              'title' => 'Related Items'
             }
           ]
         }
       }
-    }
-    let(:login_password) {
+    end
+    let(:login_password) do
       {
-        "uuid" => "auuid",
-        "vaultUuid" => "avaultuuid",
-        "templateUuid" => "001",
-        "createdAt" => "2018-03-24 01:55:07 +0000 UTC",
-        "updatedAt" => "2018-03-24 01:55:07 +0000 UTC",
-        "changerUuid" => "anotheruuid",
-        "overview" => {
-          "ainfo" => "pi",
-          "ps" => 84,
-          "title" => "password title"
+        'uuid' => 'auuid',
+        'vaultUuid' => 'avaultuuid',
+        'templateUuid' => '001',
+        'createdAt' => '2018-03-24 01:55:07 +0000 UTC',
+        'updatedAt' => '2018-03-24 01:55:07 +0000 UTC',
+        'changerUuid' => 'anotheruuid',
+        'overview' => {
+          'ainfo' => 'pi',
+          'ps' => 84,
+          'title' => 'password title'
         },
-        "details" => {
-          "fields" => [
+        'details' => {
+          'fields' => [
             {
-              "designation" => "username",
-              "name" => "username",
-              "type" => "T",
-              "value" => "theusername"
+              'designation' => 'username',
+              'name' => 'username',
+              'type' => 'T',
+              'value' => 'theusername'
             },
             {
-              "designation" => "password",
-              "name" => "password",
-              "type" => "P",
-              "value" => "thepassword"
+              'designation' => 'password',
+              'name' => 'password',
+              'type' => 'P',
+              'value' => 'thepassword'
             }
           ],
-          "sections" => [
+          'sections' => [
             {
-              "name" => "linked items",
-              "title" => "Related Items"
+              'name' => 'linked items',
+              'title' => 'Related Items'
             }
           ]
         }
       }
-    }
-    let(:password) {
+    end
+    let(:password) do
       {
-        "uuid" => "auuid",
-        "vaultUuid" => "avaultuuid",
-        "templateUuid" => "005",
-        "createdAt" => "2018-04-24 11:07:34 +0000 UTC",
-        "updatedAt" => "2018-04-24 11:07:34 +0000 UTC",
-        "changerUuid" => "antheruuid",
-        "overview" => {
-          "ainfo" => "24 Apr 2018, 9:07:34 pm",
-          "ps" => 100,
-          "title" => "password title"
+        'uuid' => 'auuid',
+        'vaultUuid' => 'avaultuuid',
+        'templateUuid' => '005',
+        'createdAt' => '2018-04-24 11:07:34 +0000 UTC',
+        'updatedAt' => '2018-04-24 11:07:34 +0000 UTC',
+        'changerUuid' => 'antheruuid',
+        'overview' => {
+          'ainfo' => '24 Apr 2018, 9:07:34 pm',
+          'ps' => 100,
+          'title' => 'password title'
         },
-        "details" => {
-          "password" => "thepassword",
-          "sections" => [
+        'details' => {
+          'password' => 'thepassword',
+          'sections' => [
             {
-              "name" => "linked items",
-              "title" => "Related Items"
+              'name' => 'linked items',
+              'title' => 'Related Items'
             }
           ]
         }
       }
-    }
-    let(:the_password) {
+    end
+    let(:the_password) do
       {
         'title' => 'password title',
         'type' => 'password',
         'vault' => 'Shared'
       }
-    }
-    let(:the_secureNote) {
+    end
+    let(:the_secureNote) do
       {
         'title' => 'note title',
         'type' => 'secureNote',
         'vault' => 'Shared'
       }
-    }
+    end
 
     context 'when we have set OP_SESSION_ environment' do
       before do
@@ -113,7 +113,7 @@
         it 'returns the login password' do
           allow_any_instance_of(described_class)
             .to receive(:`)
-            .with("op --version")
+            .with('op --version')
             .and_return(true)
           allow_any_instance_of(described_class)
             .to receive(:`)
@@ -128,7 +128,7 @@
         it 'returns the password' do
           allow_any_instance_of(described_class)
             .to receive(:`)
-            .with("op --version")
+            .with('op --version')
             .and_return(true)
           allow_any_instance_of(described_class)
             .to receive(:`)
@@ -143,7 +143,7 @@
         it 'returns the secureNote' do
           allow_any_instance_of(described_class)
             .to receive(:`)
-            .with("op --version")
+            .with('op --version')
             .and_return(true)
           allow_any_instance_of(described_class)
             .to receive(:`)
@@ -164,7 +164,7 @@
             .and_return([])
           allow_any_instance_of(described_class)
             .to receive(:`)
-            .with("op --version")
+            .with('op --version')
             .and_return(true)
           allow_any_instance_of(described_class)
             .to receive(:`)
@@ -174,7 +174,7 @@
           expect { resolver.resolve(the_password) }
             .to raise_error(
               StackMaster::ParameterResolvers::OnePassword::OnePasswordNotAbleToAuthenticate,
-              "1password requires the `OP_SESSION_<name>` to be set, (remember to sign in?)"
+              '1password requires the `OP_SESSION_<name>` to be set, (remember to sign in?)'
             )
         end
       end
@@ -186,12 +186,12 @@
       end
 
       it 'we return an error' do
-        allow_any_instance_of(described_class).to receive(:`).with("op --version").and_raise(Errno::ENOENT)
+        allow_any_instance_of(described_class).to receive(:`).with('op --version').and_raise(Errno::ENOENT)
 
         expect { resolver.resolve(the_password) }
           .to raise_error(
             StackMaster::ParameterResolvers::OnePassword::OnePasswordBinaryNotFound,
-            "The op cli needs to be installed and in the PATH, No such file or directory"
+            'The op cli needs to be installed and in the PATH, No such file or directory'
           )
       end
     end
@@ -204,7 +204,7 @@
       it 'we return an error' do
         allow_any_instance_of(described_class)
           .to receive(:`)
-          .with("op --version")
+          .with('op --version')
           .and_return(true)
         allow_any_instance_of(described_class)
           .to receive(:`)
@@ -227,7 +227,7 @@
       it 'we return an error' do
         allow_any_instance_of(described_class)
           .to receive(:`)
-          .with("op --version")
+          .with('op --version')
           .and_return(true)
         allow_any_instance_of(described_class)
           .to receive(:`)
diff --git a/spec/stack_master/parameter_resolvers/parameter_store_spec.rb b/spec/stack_master/parameter_resolvers/parameter_store_spec.rb
index 98a0b28c..70852c19 100644
--- a/spec/stack_master/parameter_resolvers/parameter_store_spec.rb
+++ b/spec/stack_master/parameter_resolvers/parameter_store_spec.rb
@@ -16,7 +16,7 @@
               parameter: {
                 name: parameter_name,
                 value: parameter_value,
-                type: "SecureString",
+                type: 'SecureString',
                 version: 1
               }
             }
diff --git a/spec/stack_master/parameter_resolvers/security_group_spec.rb b/spec/stack_master/parameter_resolvers/security_group_spec.rb
index 69491e36..f16d17d1 100644
--- a/spec/stack_master/parameter_resolvers/security_group_spec.rb
+++ b/spec/stack_master/parameter_resolvers/security_group_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe StackMaster::ParameterResolvers::SecurityGroup do
-  describe "#resolve" do
+  describe '#resolve' do
     subject(:resolver) { described_class.new(nil, double(region: 'us-east-1')) }
     let(:finder) { instance_double(StackMaster::SecurityGroupFinder) }
     let(:sg_id) { 'sg-id' }
@@ -11,7 +11,7 @@
     end
 
     context 'when given a single SG name' do
-      it "resolves the security group" do
+      it 'resolves the security group' do
         expect(resolver.resolve(sg_name)).to eq sg_id
       end
     end
diff --git a/spec/stack_master/parameter_resolvers/security_groups_spec.rb b/spec/stack_master/parameter_resolvers/security_groups_spec.rb
index 461fe044..6b87dd15 100644
--- a/spec/stack_master/parameter_resolvers/security_groups_spec.rb
+++ b/spec/stack_master/parameter_resolvers/security_groups_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe StackMaster::ParameterResolvers::SecurityGroups do
-  describe "#resolve" do
+  describe '#resolve' do
     subject(:resolver) { described_class.new(nil, double(region: 'us-east-1')) }
     let(:finder) { instance_double(StackMaster::SecurityGroupFinder) }
     let(:sg_id) { 'sg-id' }
@@ -11,7 +11,7 @@
     end
 
     context 'when given a single SG name' do
-      it "resolves the security group" do
+      it 'resolves the security group' do
         expect(resolver.resolve(sg_name)).to eq sg_id
       end
     end
@@ -24,7 +24,7 @@
         expect(finder).to receive(:find).once.with(sg_name2).and_return sg_id2
       end
 
-      it "resolves the security groups" do
+      it 'resolves the security groups' do
         expect(resolver.resolve([sg_name, sg_name2])).to eq "#{sg_id},#{sg_id2}"
       end
     end
diff --git a/spec/stack_master/parameter_resolvers/sns_topic_name_spec.rb b/spec/stack_master/parameter_resolvers/sns_topic_name_spec.rb
index 87aaef28..45b9559e 100644
--- a/spec/stack_master/parameter_resolvers/sns_topic_name_spec.rb
+++ b/spec/stack_master/parameter_resolvers/sns_topic_name_spec.rb
@@ -13,9 +13,9 @@ def resolve(value)
     let(:value) { { not_expected: 1 } }
 
     it 'raises an error' do
-      expect {
+      expect do
         resolved_value
-      }.to raise_error(ArgumentError)
+      end.to raise_error(ArgumentError)
     end
   end
 
@@ -34,9 +34,9 @@ def resolve(value)
 
     context "the topic doesn't exist" do
       it 'raises topic not found' do
-        expect {
+        expect do
           resolved_value
-        }.to raise_error(StackMaster::ParameterResolvers::SnsTopicName::TopicNotFound)
+        end.to raise_error(StackMaster::ParameterResolvers::SnsTopicName::TopicNotFound)
       end
     end
   end
diff --git a/spec/stack_master/parameter_resolvers/sso_group_id_spec.rb b/spec/stack_master/parameter_resolvers/sso_group_id_spec.rb
index 85eef6cd..56b20398 100644
--- a/spec/stack_master/parameter_resolvers/sso_group_id_spec.rb
+++ b/spec/stack_master/parameter_resolvers/sso_group_id_spec.rb
@@ -28,9 +28,9 @@
       it 'propagates the SsoGroupNotFound error' do
         allow(finder).to receive(:find).and_raise(StackMaster::SsoGroupIdFinder::SsoGroupNotFound)
 
-        expect {
+        expect do
           resolver.resolve(group_reference)
-        }.to raise_error(StackMaster::SsoGroupIdFinder::SsoGroupNotFound)
+        end.to raise_error(StackMaster::SsoGroupIdFinder::SsoGroupNotFound)
       end
     end
 
@@ -40,9 +40,9 @@
       it 'raises ArgumentError from SsoGroupIdFinder' do
         allow(finder).to receive(:find).and_raise(ArgumentError)
 
-        expect {
+        expect do
           resolver.resolve(invalid_reference)
-        }.to raise_error(ArgumentError)
+        end.to raise_error(ArgumentError)
       end
     end
   end
diff --git a/spec/stack_master/parameter_resolvers/stack_output_spec.rb b/spec/stack_master/parameter_resolvers/stack_output_spec.rb
index 6f979ea5..761d0b6c 100644
--- a/spec/stack_master/parameter_resolvers/stack_output_spec.rb
+++ b/spec/stack_master/parameter_resolvers/stack_output_spec.rb
@@ -3,7 +3,7 @@
   let(:stack_name) { 'my-stack' }
   let(:resolver) { described_class.new(config, double(region: 'us-east-1')) }
   let(:cf) { Aws::CloudFormation::Client.new }
-  let(:config) { double(:unalias_region => region) }
+  let(:config) { double(unalias_region: region) }
 
   def resolve(value)
     resolver.resolve(value)
@@ -15,9 +15,9 @@ def resolve(value)
     let(:value) { 'stack-name-without-output' }
 
     it 'raises an error' do
-      expect {
+      expect do
         resolved_value
-      }.to raise_error(ArgumentError)
+      end.to raise_error(ArgumentError)
     end
   end
 
@@ -25,17 +25,17 @@ def resolve(value)
     let(:value) { { not_expected: 1 } }
 
     it 'raises an error' do
-      expect {
+      expect do
         resolved_value
-      }.to raise_error(ArgumentError)
+      end.to raise_error(ArgumentError)
     end
   end
 
   context 'when given a valid string value' do
     let(:value) { 'my-stack/MyOutput' }
-    let(:stacks) {
+    let(:stacks) do
       [{ stack_name: 'blah', creation_time: Time.now, stack_status: 'CREATE_COMPLETE', outputs: outputs }]
-    }
+    end
     let(:outputs) { [] }
 
     before do
@@ -61,7 +61,7 @@ def resolve(value)
         resolver.resolve(value)
       end
 
-      it "caches stacks by region" do
+      it 'caches stacks by region' do
         expect(cf).to receive(:describe_stacks).with({ stack_name: 'my-stack' }).and_call_original.twice
         resolver.resolve(value)
         resolver.resolve(value)
@@ -78,9 +78,9 @@ def resolve(value)
         end
       end
 
-      context "when different credentials are used" do
+      context 'when different credentials are used' do
         let(:outputs_in_account_2) { [{ output_key: 'MyOutput', output_value: 'resolvedvalueinaccount2' }] }
-        let(:stacks_in_account_2) {
+        let(:stacks_in_account_2) do
           [
             {
               stack_name: 'other-stack',
@@ -89,7 +89,7 @@ def resolve(value)
               outputs: outputs_in_account_2
             }
           ]
-        }
+        end
 
         before do
           cf.stub_responses(
@@ -99,23 +99,23 @@ def resolve(value)
           )
         end
 
-        it "caches stacks by credentials" do
+        it 'caches stacks by credentials' do
           expect(cf).to receive(:describe_stacks).with({ stack_name: 'my-stack' }).and_call_original.twice
           resolver.resolve(value)
           resolver.resolve(value)
-          Aws.config[:credentials] = "my-credentials"
+          Aws.config[:credentials] = 'my-credentials'
           resolver.resolve(value)
           resolver.resolve(value)
           Aws.config.delete(:credentials)
         end
 
-        it "caches CF clients by region and credentials" do
+        it 'caches CF clients by region and credentials' do
           expect(Aws::CloudFormation::Client).to receive(:new).and_return(cf).exactly(3).times
           resolver.resolve(value)
           resolver.resolve(value)
           resolver.resolve('other-stack/MyOutput')
           resolver.resolve('other-stack/MyOutput')
-          Aws.config[:credentials] = "my-credentials"
+          Aws.config[:credentials] = 'my-credentials'
           resolver.resolve('other-stack/MyOutput')
           resolver.resolve('other-stack/MyOutput')
           resolver.resolve('ap-southeast-2:other-stack/MyOutput')
@@ -129,9 +129,9 @@ def resolve(value)
       let(:stacks) { nil }
 
       it 'resolves the value' do
-        expect {
+        expect do
           resolved_value
-        }.to raise_error(StackMaster::ParameterResolvers::StackOutput::StackNotFound)
+        end.to raise_error(StackMaster::ParameterResolvers::StackOutput::StackNotFound)
       end
     end
 
@@ -139,18 +139,18 @@ def resolve(value)
       let(:outputs) { [] }
 
       it 'resolves the value' do
-        expect {
+        expect do
           resolved_value
-        }.to raise_error(StackMaster::ParameterResolvers::StackOutput::StackOutputNotFound)
+        end.to raise_error(StackMaster::ParameterResolvers::StackOutput::StackOutputNotFound)
       end
     end
   end
 
   context 'when given a valid string value including region' do
     let(:value) { 'us-east-1:my-stack/MyOutput' }
-    let(:stacks) {
+    let(:stacks) do
       [{ stack_name: 'my-stack', creation_time: Time.now, stack_status: 'CREATE_COMPLETE', outputs: outputs }]
-    }
+    end
     let(:outputs) { [] }
 
     before do
@@ -169,7 +169,7 @@ def resolve(value)
         let(:value_in_region_alias) { 'global:my-stack/MyOutput' }
         let(:value_in_region_2) { 'ap-southeast-2:my-stack/MyOutput' }
         let(:outputs_in_region_2) { [{ output_key: 'MyOutput', output_value: 'myresolvedvalue2' }] }
-        let(:stacks_in_region_2) {
+        let(:stacks_in_region_2) do
           [
             {
               stack_name: 'my-stack',
@@ -178,7 +178,7 @@ def resolve(value)
               outputs: outputs_in_region_2
             }
           ]
-        }
+        end
 
         before do
           cf.stub_responses(
diff --git a/spec/stack_master/parameter_validator_spec.rb b/spec/stack_master/parameter_validator_spec.rb
index 19fbedad..81dda3c6 100644
--- a/spec/stack_master/parameter_validator_spec.rb
+++ b/spec/stack_master/parameter_validator_spec.rb
@@ -41,7 +41,7 @@
 
     context 'when the stack definition is using explicit parameter files' do
       let(:parameters) { { 'Param1' => true, 'Param2' => nil, 'Param3' => 'string', 'Param4' => nil } }
-      let(:parameter_files) { ["params.yml"] }
+      let(:parameter_files) { ['params.yml'] }
 
       it 'returns a descriptive message' do
         expect(error_message).to eq(<<~MESSAGE)
diff --git a/spec/stack_master/security_group_finder_spec.rb b/spec/stack_master/security_group_finder_spec.rb
index 678dbeba..cf9c2d99 100644
--- a/spec/stack_master/security_group_finder_spec.rb
+++ b/spec/stack_master/security_group_finder_spec.rb
@@ -1,50 +1,50 @@
 RSpec.describe StackMaster::SecurityGroupFinder do
   subject(:finder) { described_class.new(region) }
   let(:region) { 'us-east-1' }
-  let(:group_name) { "our-api-BeanstalkSg-T4RKD99YOY2F" }
+  let(:group_name) { 'our-api-BeanstalkSg-T4RKD99YOY2F' }
   let(:filter) do
     {
       filters: [
         {
-          name: "group-name",
-          values: [group_name],
-        },
-      ],
+          name: 'group-name',
+          values: [group_name]
+        }
+      ]
     }
   end
 
-  describe "#find" do
+  describe '#find' do
     before do
       allow_any_instance_of(Aws::EC2::Resource).to receive(:security_groups).with(filter).and_return(security_groups)
     end
 
-    context "one sg match" do
-      let(:security_groups) {
+    context 'one sg match' do
+      let(:security_groups) do
         [
           double(id: 'sg-a7d2ccc0')
         ]
-      }
-      it "returns the id" do
+      end
+      it 'returns the id' do
         expect(finder.find(group_name)).to eq 'sg-a7d2ccc0'
       end
     end
 
-    context "more than one sg matches" do
-      let(:security_groups) {
+    context 'more than one sg matches' do
+      let(:security_groups) do
         [
           double(id: 'sg-a7d2ccc0'),
-          double(id: 'sg-a7d2ccc2'),
+          double(id: 'sg-a7d2ccc2')
         ]
-      }
-      it "returns the id" do
+      end
+      it 'returns the id' do
         err = StackMaster::SecurityGroupFinder::MultipleSecurityGroupsFound
         expect { finder.find(group_name) }.to raise_error(err)
       end
     end
 
-    context "no matches" do
+    context 'no matches' do
       let(:security_groups) { [] }
-      it "returns the id" do
+      it 'returns the id' do
         err = StackMaster::SecurityGroupFinder::SecurityGroupNotFound
         expect { finder.find(group_name) }.to raise_error(err)
       end
diff --git a/spec/stack_master/sns_topic_finder_spec.rb b/spec/stack_master/sns_topic_finder_spec.rb
index c206a5cc..bff34852 100644
--- a/spec/stack_master/sns_topic_finder_spec.rb
+++ b/spec/stack_master/sns_topic_finder_spec.rb
@@ -4,7 +4,7 @@
   let(:topics) do
     [
       double(arn: 'arn:aws:sns:us-east-1:581634149801:topic1name'),
-      double(arn: 'arn:aws:sns:us-east-1:581634149801:topic2name'),
+      double(arn: 'arn:aws:sns:us-east-1:581634149801:topic2name')
     ]
   end
   before do
diff --git a/spec/stack_master/sparkle_formation/compile_time/definitions_validator_spec.rb b/spec/stack_master/sparkle_formation/compile_time/definitions_validator_spec.rb
index 6a6a2b8b..be8f6e33 100644
--- a/spec/stack_master/sparkle_formation/compile_time/definitions_validator_spec.rb
+++ b/spec/stack_master/sparkle_formation/compile_time/definitions_validator_spec.rb
@@ -5,7 +5,7 @@
 
     subject { described_class.new(definition) }
 
-    [:string, :number].each do |type|
+    %i[string number].each do |type|
       context "with :#{type} type definition" do
         let(:type) { type }
 
@@ -22,7 +22,7 @@
         expect { subject.validate }
           .to raise_error(
             ArgumentError,
-            "Unknown compile time parameter type: #{key}:#{type} valid types are #{[:string, :number]}"
+            "Unknown compile time parameter type: #{key}:#{type} valid types are #{%i[string number]}"
           )
       end
     end
diff --git a/spec/stack_master/sparkle_formation/compile_time/value_build_spec.rb b/spec/stack_master/sparkle_formation/compile_time/value_build_spec.rb
index ba0e1d03..bf53d54b 100644
--- a/spec/stack_master/sparkle_formation/compile_time/value_build_spec.rb
+++ b/spec/stack_master/sparkle_formation/compile_time/value_build_spec.rb
@@ -7,8 +7,8 @@
     { definition: { type: :string, default: 'a' }, parameter: nil, expected: 'a' },
 
     { definition: { type: :string, multiple: true }, parameter: 'a', expected: ['a'] },
-    { definition: { type: :string, multiple: true }, parameter: 'a,b', expected: ['a', 'b'] },
-    { definition: { type: :string, multiple: true }, parameter: 'a, b', expected: ['a', 'b'] },
+    { definition: { type: :string, multiple: true }, parameter: 'a,b', expected: %w[a b] },
+    { definition: { type: :string, multiple: true }, parameter: 'a, b', expected: %w[a b] },
 
     { definition: { type: :string, multiple: true, default: 'a' }, parameter: nil, expected: ['a'] },
 
diff --git a/spec/stack_master/sparkle_formation/template_file_spec.rb b/spec/stack_master/sparkle_formation/template_file_spec.rb
index 4c10f08a..a075c6b3 100644
--- a/spec/stack_master/sparkle_formation/template_file_spec.rb
+++ b/spec/stack_master/sparkle_formation/template_file_spec.rb
@@ -12,7 +12,7 @@
     EOS
   end
   let(:expected_hash) do
-    { "Fn::Base64" => { "Fn::Join" => ["", ["#!/bin/bash\n", "\n", "REGION=", { "Ref" => "AWS::Region" }, "\n", "echo $REGION\n", { "Ref" => "Test" }, " ", { "Ref" => "Test2" }, "\n", "echo 'no'", "\n"]] } }
+    { 'Fn::Base64' => { 'Fn::Join' => ['', ["#!/bin/bash\n", "\n", 'REGION=', { 'Ref' => 'AWS::Region' }, "\n", "echo $REGION\n", { 'Ref' => 'Test' }, ' ', { 'Ref' => 'Test2' }, "\n", "echo 'no'", "\n"]] } }
   end
 
   before do
@@ -48,7 +48,7 @@
         EOS
       end
       let(:expected_hash) do
-        { "Fn::Base64" => { "Fn::Join" => ["", ["#!/bin/bash\n", "test_var", "\n", "yes", "\n"]] } }
+        { 'Fn::Base64' => { 'Fn::Join' => ['', ["#!/bin/bash\n", 'test_var', "\n", 'yes', "\n"]] } }
       end
 
       it 'compiles the file and returns a joined version' do
@@ -64,9 +64,9 @@
     end
 
     it 'raises a specific error' do
-      expect {
+      expect do
         @attr.user_data_file!('test.erb')
-      }.to raise_error(StackMaster::SparkleFormation::TemplateFileNotFound)
+      end.to raise_error(StackMaster::SparkleFormation::TemplateFileNotFound)
     end
   end
 
@@ -88,7 +88,7 @@
     end
 
     let(:expected_hash) do
-      { "Fn::Base64" => { "Fn::Join" => ["", ["#!/bin/bash\n", "outer1", " ", "outer2", "\n", "REGION=", { "Ref" => "AWS::Region" }, "\n", "inner1", "\n", "no", "\n", "\n"]] } }
+      { 'Fn::Base64' => { 'Fn::Join' => ['', ["#!/bin/bash\n", 'outer1', ' ', 'outer2', "\n", 'REGION=', { 'Ref' => 'AWS::Region' }, "\n", 'inner1', "\n", 'no', "\n", "\n"]] } }
     end
 
     before do
@@ -111,7 +111,7 @@
   end
 
   let(:expected_hash) do
-    { "Fn::Join" => ["", ["variable=", { "Ref" => "Test" }, "\n"]] }
+    { 'Fn::Join' => ['', ['variable=', { 'Ref' => 'Test' }, "\n"]] }
   end
 
   before do
diff --git a/spec/stack_master/sso_group_id_finder_spec.rb b/spec/stack_master/sso_group_id_finder_spec.rb
index 04bbaa78..75553a43 100644
--- a/spec/stack_master/sso_group_id_finder_spec.rb
+++ b/spec/stack_master/sso_group_id_finder_spec.rb
@@ -45,7 +45,7 @@
       it 'raises SsoGroupNotFound' do
         error = Aws::IdentityStore::Errors::ResourceNotFoundException.new(
           Seahorse::Client::RequestContext.new,
-          "Group not found"
+          'Group not found'
         )
 
         expect(aws_client).to receive(:get_group_id).and_raise(error)
diff --git a/spec/stack_master/stack_definition_spec.rb b/spec/stack_master/stack_definition_spec.rb
index 3e901552..1b693f27 100644
--- a/spec/stack_master/stack_definition_spec.rb
+++ b/spec/stack_master/stack_definition_spec.rb
@@ -23,7 +23,7 @@
     ).and_return(
       [
         "/base_dir/parameters/#{stack_name}.yaml",
-        "/base_dir/parameters/#{stack_name}.yml",
+        "/base_dir/parameters/#{stack_name}.yml"
       ]
     )
 
@@ -32,7 +32,7 @@
     ).and_return(
       [
         "/base_dir/parameters/#{region}/#{stack_name}.yaml",
-        "/base_dir/parameters/#{region}/#{stack_name}.yml",
+        "/base_dir/parameters/#{region}/#{stack_name}.yml"
       ]
     )
   end
@@ -43,7 +43,7 @@
         "/base_dir/parameters/#{stack_name}.yaml",
         "/base_dir/parameters/#{stack_name}.yml",
         "/base_dir/parameters/#{region}/#{stack_name}.yaml",
-        "/base_dir/parameters/#{region}/#{stack_name}.yml",
+        "/base_dir/parameters/#{region}/#{stack_name}.yml"
       ]
     )
   end
@@ -52,7 +52,7 @@
     expect(stack_definition.parameter_file_globs).to eq(
       [
         "/base_dir/parameters/#{stack_name}.y*ml",
-        "/base_dir/parameters/#{region}/#{stack_name}.y*ml",
+        "/base_dir/parameters/#{region}/#{stack_name}.y*ml"
       ]
     )
   end
@@ -63,8 +63,8 @@
     it 'returns globs supporting dashes and underscores in the parameter filenames' do
       expect(stack_definition.parameter_file_globs).to eq(
         [
-          "/base_dir/parameters/stack[-_]name.y*ml",
-          "/base_dir/parameters/#{region}/stack[-_]name.y*ml",
+          '/base_dir/parameters/stack[-_]name.y*ml',
+          "/base_dir/parameters/#{region}/stack[-_]name.y*ml"
         ]
       )
     end
@@ -74,11 +74,11 @@
     before do
       stack_definition.additional_parameter_lookup_dirs = ['production']
       allow(Dir).to receive(:glob).with(
-        File.join(base_dir, 'parameters', "production", "#{stack_name}.y*ml")
+        File.join(base_dir, 'parameters', 'production', "#{stack_name}.y*ml")
       ).and_return(
         [
           "/base_dir/parameters/production/#{stack_name}.yaml",
-          "/base_dir/parameters/production/#{stack_name}.yml",
+          "/base_dir/parameters/production/#{stack_name}.yml"
         ]
       )
     end
@@ -91,7 +91,7 @@
           "/base_dir/parameters/#{region}/#{stack_name}.yaml",
           "/base_dir/parameters/#{region}/#{stack_name}.yml",
           "/base_dir/parameters/production/#{stack_name}.yaml",
-          "/base_dir/parameters/production/#{stack_name}.yml",
+          "/base_dir/parameters/production/#{stack_name}.yml"
         ]
       )
     end
@@ -101,7 +101,7 @@
         [
           "/base_dir/parameters/#{stack_name}.y*ml",
           "/base_dir/parameters/#{region}/#{stack_name}.y*ml",
-          "/base_dir/parameters/production/#{stack_name}.y*ml",
+          "/base_dir/parameters/production/#{stack_name}.y*ml"
         ]
       )
     end
@@ -112,9 +112,9 @@
       it 'returns globs supporting dashes and underscores in the parameter filenames' do
         expect(stack_definition.parameter_file_globs).to eq(
           [
-            "/base_dir/parameters/stack[-_]name.y*ml",
+            '/base_dir/parameters/stack[-_]name.y*ml',
             "/base_dir/parameters/#{region}/stack[-_]name.y*ml",
-            "/base_dir/parameters/production/stack[-_]name.y*ml",
+            '/base_dir/parameters/production/stack[-_]name.y*ml'
           ]
         )
       end
@@ -125,11 +125,11 @@
     expect(stack_definition.ejson_file_kms).to eq true
   end
 
-  context "with explicit parameter_files" do
-    let(:parameter_files) { ["my-stack.yml", "../my-stack.yml"] }
+  context 'with explicit parameter_files' do
+    let(:parameter_files) { ['my-stack.yml', '../my-stack.yml'] }
 
-    it "ignores parameter globs and resolves them relative to parameters_dir" do
-      expect(stack_definition.all_parameter_files).to eq ["/base_dir/parameters/my-stack.yml", "/base_dir/my-stack.yml"]
+    it 'ignores parameter globs and resolves them relative to parameters_dir' do
+      expect(stack_definition.all_parameter_files).to eq ['/base_dir/parameters/my-stack.yml', '/base_dir/my-stack.yml']
     end
   end
 end
diff --git a/spec/stack_master/stack_differ_spec.rb b/spec/stack_master/stack_differ_spec.rb
index 229458b4..9aeeaf1e 100644
--- a/spec/stack_master/stack_differ_spec.rb
+++ b/spec/stack_master/stack_differ_spec.rb
@@ -1,10 +1,10 @@
 RSpec.describe StackMaster::StackDiffer do
   subject(:differ) { described_class.new(proposed_stack, stack) }
   let(:current_body) { '{}' }
-  let(:proposed_body) { "{\"a\": 1}" }
-  let(:current_params) { Hash.new }
+  let(:proposed_body) { '{"a": 1}' }
+  let(:current_params) { {} }
   let(:proposed_params) { { 'param1' => 'hello' } }
-  let(:stack) {
+  let(:stack) do
     StackMaster::Stack.new(
       stack_name: stack_name,
       region: region,
@@ -13,8 +13,8 @@
       template_format: :json,
       parameters: current_params
     )
-  }
-  let(:proposed_stack) {
+  end
+  let(:proposed_stack) do
     StackMaster::Stack.new(
       stack_name: stack_name,
       region: region,
@@ -22,43 +22,43 @@
       template_body: proposed_body,
       template_format: :json
     )
-  }
+  end
   let(:stack_name) { 'myapp-vpc' }
   let(:region) { 'us-east-1' }
 
-  describe "#proposed_parameters" do
-    let(:current_params) {
+  describe '#proposed_parameters' do
+    let(:current_params) do
       {
         'param1' => 'hello',
         'param2' => '****'
       }
-    }
-    it "stars out noecho params" do
+    end
+    it 'stars out noecho params' do
       expect(differ.proposed_parameters).to eq "---\nparam1: hello\nparam2: \"****\"\n"
     end
   end
 
-  describe "#output_diff" do
-    context "entirely new stack" do
+  describe '#output_diff' do
+    context 'entirely new stack' do
       let(:stack) { nil }
 
-      it "outputs the entire stack" do
-        expect { differ.output_diff }.to output(/\+  \"a\"\: 1/).to_stdout
-        expect { differ.output_diff }.to output(/param1\: hello/).to_stdout
+      it 'outputs the entire stack' do
+        expect { differ.output_diff }.to output(/\+  "a": 1/).to_stdout
+        expect { differ.output_diff }.to output(/param1: hello/).to_stdout
         expect { differ.output_diff }.to output(/No stack found/).to_stdout
       end
     end
 
-    context "stack update" do
-      it "outputs the stack diff" do
-        expect { differ.output_diff }.to output(/\+  \"a\"\: 1/).to_stdout
-        expect { differ.output_diff }.to output(/param1\: hello/).to_stdout
+    context 'stack update' do
+      it 'outputs the stack diff' do
+        expect { differ.output_diff }.to output(/\+  "a": 1/).to_stdout
+        expect { differ.output_diff }.to output(/param1: hello/).to_stdout
         expect { differ.output_diff }.to_not output(/No stack found/).to_stdout
       end
     end
   end
 
-  describe "#single_param_update?" do
+  describe '#single_param_update?' do
     let(:yes_param) { 'YesParam' }
     let(:old_value) { 'old' }
     let(:new_value) { 'new' }
@@ -68,36 +68,36 @@
 
     subject(:result) { differ.single_param_update?(yes_param) }
 
-    context "when only param changes" do
+    context 'when only param changes' do
       it { is_expected.to be_truthy }
     end
 
-    context "when new stack" do
+    context 'when new stack' do
       let(:stack) { nil }
       it { is_expected.to be_falsey }
     end
 
-    context "when no changes" do
+    context 'when no changes' do
       let(:current_params) { proposed_params }
       it { is_expected.to be_falsey }
     end
 
-    context "when body changes" do
+    context 'when body changes' do
       let(:current_body) { '{}' }
       it { is_expected.to be_falsey }
     end
 
-    context "on param removal" do
+    context 'on param removal' do
       let(:proposed_params) { {} }
       it { is_expected.to be_falsey }
     end
 
-    context "on param first addition" do
+    context 'on param first addition' do
       let(:current_params) { {} }
       it { is_expected.to be_falsey }
     end
 
-    context "when another param also changes" do
+    context 'when another param also changes' do
       let(:current_params) { { yes_param => old_value, 'other' => 'old' } }
       let(:proposed_params) { { yes_param => new_value, 'other' => 'new' } }
       it { is_expected.to be_falsey }
diff --git a/spec/stack_master/stack_events/fetcher_spec.rb b/spec/stack_master/stack_events/fetcher_spec.rb
index 847e9fd8..42684f80 100644
--- a/spec/stack_master/stack_events/fetcher_spec.rb
+++ b/spec/stack_master/stack_events/fetcher_spec.rb
@@ -17,12 +17,12 @@
   end
 
   context 'with 2 stack events' do
-    let(:events) {
+    let(:events) do
       [
         OpenStruct.new(event_id: '1', stack_id: '1', stack_name: 'blah', timestamp: Time.now),
         OpenStruct.new(event_id: '2', stack_id: '1', stack_name: 'blah', timestamp: Time.now)
       ]
-    }
+    end
 
     it 'returns stack events' do
       events = StackMaster::StackEvents::Fetcher.fetch(stack_name, 'us-east-1')
@@ -35,12 +35,12 @@
     let(:three_pm) { Time.parse('2015-10-27 15:00') }
     let(:four_pm) { Time.parse('2015-10-27 16:00') }
 
-    let(:events) {
+    let(:events) do
       [
         OpenStruct.new(event_id: '1', stack_id: '1', stack_name: 'blah', timestamp: two_pm),
-        OpenStruct.new(event_id: '2', stack_id: '1', stack_name: 'blah', timestamp: four_pm),
+        OpenStruct.new(event_id: '2', stack_id: '1', stack_name: 'blah', timestamp: four_pm)
       ]
-    }
+    end
 
     it 'only returns events after the timestamp' do
       events = StackMaster::StackEvents::Fetcher.fetch(stack_name, 'us-east-1', from: three_pm)
diff --git a/spec/stack_master/stack_events/presenter_spec.rb b/spec/stack_master/stack_events/presenter_spec.rb
index 23c511bf..f65ad554 100644
--- a/spec/stack_master/stack_events/presenter_spec.rb
+++ b/spec/stack_master/stack_events/presenter_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe StackMaster::StackEvents::Presenter do
-  describe "#print_event" do
+  describe '#print_event' do
     let(:time) { Time.new(2001, 1, 1, 2, 2, 2) }
     let(:event) do
       double(
@@ -13,9 +13,9 @@
     end
     subject(:print_event) { described_class.print_event($stdout, event) }
 
-    it "nicely presents event data" do
+    it 'nicely presents event data' do
       expect { print_event }.to output("\e[33m2001-01-01 02:02:02 #{time.strftime('%z')} " \
-                                       "MyAwesomeQueue AWS::SQS::Queue CREATE_IN_PROGRESS " \
+                                       'MyAwesomeQueue AWS::SQS::Queue CREATE_IN_PROGRESS ' \
                                        "Resource creation Initiated\e[0m\n").to_stdout
     end
   end
diff --git a/spec/stack_master/stack_events/streamer_spec.rb b/spec/stack_master/stack_events/streamer_spec.rb
index dede48be..637b1129 100644
--- a/spec/stack_master/stack_events/streamer_spec.rb
+++ b/spec/stack_master/stack_events/streamer_spec.rb
@@ -1,12 +1,12 @@
 RSpec.describe StackMaster::StackEvents::Streamer do
-  let(:events_first_call) {
+  let(:events_first_call) do
     [
       OpenStruct.new(event_id: '1', resource_status: 'BLAH', timestamp: Time.now),
       OpenStruct.new(event_id: '2', resource_status: 'BLAH', timestamp: Time.now),
-      OpenStruct.new(event_id: '3', resource_status: 'BLAH', timestamp: Time.now),
+      OpenStruct.new(event_id: '3', resource_status: 'BLAH', timestamp: Time.now)
     ]
-  }
-  let(:events_second_call) {
+  end
+  let(:events_second_call) do
     events_first_call + [
       OpenStruct.new(
         event_id: '4',
@@ -16,7 +16,7 @@
         timestamp: Time.now
       )
     ]
-  }
+  end
   let(:stack_name) { 'stack-name' }
   let(:region) { 'us-east-1' }
   let(:now) { Time.now }
@@ -42,8 +42,8 @@
     expect(io.string).to include('UPDATE_COMPLETE')
   end
 
-  context "the stack is in a failed state" do
-    let(:events_second_call) {
+  context 'the stack is in a failed state' do
+    let(:events_second_call) do
       events_first_call + [
         OpenStruct.new(
           event_id: '4',
@@ -53,7 +53,7 @@
           timestamp: Time.now
         )
       ]
-    }
+    end
 
     it 'raises an error on failure' do
       expect { StackMaster::StackEvents::Streamer.stream(stack_name, region, sleep_between_fetches: 0) }
diff --git a/spec/stack_master/stack_spec.rb b/spec/stack_master/stack_spec.rb
index 36abf957..0aa823c0 100644
--- a/spec/stack_master/stack_spec.rb
+++ b/spec/stack_master/stack_spec.rb
@@ -12,12 +12,12 @@
 
   describe '.find' do
     context 'when the stack exists in AWS' do
-      let(:parameters) {
+      let(:parameters) do
         [
           { parameter_key: 'param1', parameter_value: 'value1' },
           { parameter_key: 'param2', parameter_value: 'value2' }
         ]
-      }
+      end
       before do
         cf.stub_responses(
           :describe_stacks,
@@ -35,7 +35,7 @@
             ]
           }
         )
-        cf.stub_responses(:get_template, { template_body: "{}" })
+        cf.stub_responses(:get_template, { template_body: '{}' })
         cf.stub_responses(:get_stack_policy, { stack_policy_body: stack_policy_body })
       end
 
@@ -43,8 +43,8 @@
         expect(stack.stack_id).to eq stack_id
       end
 
-      it "returns a template body" do
-        expect(stack.template_body).to eq "{}"
+      it 'returns a template body' do
+        expect(stack.template_body).to eq '{}'
       end
 
       it 'parses parameters into a hash' do
@@ -212,12 +212,12 @@
     let(:stack_definition) { StackMaster::StackDefinition.new(region: region, stack_name: stack_name, tags: tags, base_dir: '/base_dir', template: template_file_name, notification_arns: ['test_arn'], role_arn: 'test_service_role_arn', stack_policy_file: 'no_replace_rds.json') }
     let(:config) { StackMaster::Config.new({ 'stacks' => {} }, '/base_dir') }
     subject(:stack) { StackMaster::Stack.generate(stack_definition, config) }
-    let(:parameter_hash) {
+    let(:parameter_hash) do
       { template_parameters: { 'DbPassword' => { 'secret' => 'db_password' } }, compile_time_parameters: {} }
-    }
-    let(:resolved_template_parameters) {
+    end
+    let(:resolved_template_parameters) do
       { 'DbPassword' => 'sdfgjkdhlfjkghdflkjghdflkjg', 'InstanceType' => 't2.medium' }
-    }
+    end
     let(:resolved_compile_time_parameters) { {} }
     let(:template_file_name) { 'template.rb' }
     let(:template_body) { <<~JSON }
@@ -321,8 +321,8 @@
   end
 
   describe '#too_big?' do
-    let(:big_stack) { described_class.new(template_body: "{\"a\":\"#{'x' * 500000}\"}") }
-    let(:medium_stack) { described_class.new(template_body: "{\"a\":\"#{'x' * 60000}\"}") }
+    let(:big_stack) { described_class.new(template_body: "{\"a\":\"#{'x' * 500_000}\"}") }
+    let(:medium_stack) { described_class.new(template_body: "{\"a\":\"#{'x' * 60_000}\"}") }
     let(:little_stack) { described_class.new(template_body: "{\"a\":\"#{'x' * 1000}\"}") }
 
     context 'when not using S3' do
diff --git a/spec/stack_master/template_compiler_spec.rb b/spec/stack_master/template_compiler_spec.rb
index 1c321e00..43fa7ffd 100644
--- a/spec/stack_master/template_compiler_spec.rb
+++ b/spec/stack_master/template_compiler_spec.rb
@@ -28,9 +28,9 @@ def self.compile(template_dir, template, compile_time_parameters, compile_option
     end
 
     context 'when a template compiler is registered for the given file type' do
-      before {
+      before do
         StackMaster::TemplateCompiler.register(:test_template_compiler, TestTemplateCompiler)
-      }
+      end
 
       it 'compiles the template using the relevant template compiler' do
         expect(TestTemplateCompiler)
@@ -48,7 +48,7 @@ def self.compile(template_dir, template, compile_time_parameters, compile_option
       end
 
       it 'passes compile_options to the template compiler' do
-        opts = { foo: 1, bar: true, baz: "meh" }
+        opts = { foo: 1, bar: true, baz: 'meh' }
         expect(TestTemplateCompiler).to receive(:compile).with(nil, template, compile_time_parameters, opts)
         StackMaster::TemplateCompiler.compile(config, nil, nil, template, compile_time_parameters, opts)
       end
@@ -57,7 +57,7 @@ def self.compile(template_dir, template, compile_time_parameters, compile_option
         before { allow(TestTemplateCompiler).to receive(:compile).and_raise(RuntimeError) }
 
         it 'raise TemplateCompilationFailed exception' do
-          expect {
+          expect do
             StackMaster::TemplateCompiler.compile(
               config,
               nil,
@@ -66,7 +66,7 @@ def self.compile(template_dir, template, compile_time_parameters, compile_option
               compile_time_parameters,
               compile_time_parameters
             )
-          }.to raise_error(StackMaster::TemplateCompiler::TemplateCompilationFailed, /^Failed to compile/)
+          end.to raise_error(StackMaster::TemplateCompiler::TemplateCompilationFailed, /^Failed to compile/)
         end
       end
     end
diff --git a/spec/stack_master/template_compilers/cfndsl_spec.rb b/spec/stack_master/template_compilers/cfndsl_spec.rb
index fa58f1b9..1e196a49 100644
--- a/spec/stack_master/template_compilers/cfndsl_spec.rb
+++ b/spec/stack_master/template_compilers/cfndsl_spec.rb
@@ -33,8 +33,8 @@ def compile
         let(:template) { 'sample-ctp-repeated.rb' }
 
         it 'does not leak compile time params across invocations' do
-          expect { compile_time_parameters.delete("DisableApiTermination") }
-            .to change { JSON.parse(compile)["Resources"]["MyInstance"]["Properties"]["DisableApiTermination"] }
+          expect { compile_time_parameters.delete('DisableApiTermination') }
+            .to change { JSON.parse(compile)['Resources']['MyInstance']['Properties']['DisableApiTermination'] }
             .from('true')
             .to('false')
         end
diff --git a/spec/stack_master/template_compilers/json_spec.rb b/spec/stack_master/template_compilers/json_spec.rb
index b0d6997f..5792c6eb 100644
--- a/spec/stack_master/template_compilers/json_spec.rb
+++ b/spec/stack_master/template_compilers/json_spec.rb
@@ -6,28 +6,28 @@ def compile
       described_class.compile(stack_definition.template_dir, stack_definition.template, compile_time_parameters)
     end
 
-    let(:stack_definition) {
+    let(:stack_definition) do
       StackMaster::StackDefinition.new(template_dir: File.dirname(template_file_path),
                                        template: File.basename(template_file_path))
-    }
+    end
     let(:template_file_path) { '/base_dir/templates/template.json' }
 
-    context "small json template" do
+    context 'small json template' do
       before do
         allow(File).to receive(:read).with(template_file_path).and_return('{ }')
       end
 
-      it "reads from the template file path" do
+      it 'reads from the template file path' do
         expect(compile).to eq('{ }')
       end
     end
 
     context 'extra big json template' do
       before do
-        allow(File).to receive(:read).with(template_file_path).and_return("{ #{' ' * 60000} }")
+        allow(File).to receive(:read).with(template_file_path).and_return("{ #{' ' * 60_000} }")
       end
 
-      it "reads from the template file path" do
+      it 'reads from the template file path' do
         expect(compile).to eq('{}')
       end
     end
diff --git a/spec/stack_master/template_compilers/sparkle_formation_spec.rb b/spec/stack_master/template_compilers/sparkle_formation_spec.rb
index 5fa6145a..441004dc 100644
--- a/spec/stack_master/template_compilers/sparkle_formation_spec.rb
+++ b/spec/stack_master/template_compilers/sparkle_formation_spec.rb
@@ -3,7 +3,7 @@
   let(:compile_time_parameter_definitions) { {} }
 
   def project_path(path)
-    File.expand_path(File.join(File.dirname(__FILE__), "..", "..", "..", path))
+    File.expand_path(File.join(File.dirname(__FILE__), '..', '..', '..', path))
   end
 
   def fixture_template(file)
@@ -11,11 +11,11 @@ def fixture_template(file)
   end
 
   def template_dir
-    "spec/fixtures/templates/rb/sparkle_formation/templates"
+    'spec/fixtures/templates/rb/sparkle_formation/templates'
   end
 
   def sparkle_pack_dir
-    project_path("spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates")
+    project_path('spec/fixtures/sparkle_pack_integration/my_sparkle_pack/lib/sparkleformation/templates')
   end
 
   def sparkle_pack_template(file)
@@ -27,13 +27,13 @@ def compile
       described_class.compile(template_dir, template, compile_time_parameters, compiler_options)
     end
 
-    let(:stack_definition) {
+    let(:stack_definition) do
       instance_double(
         StackMaster::StackDefinition,
         template: template,
         template_dir: template_dir
       )
-    }
+    end
     let(:compile_time_parameters) { { 'Ip' => '10.0.0.0', 'Name' => 'Something' } }
     let(:compiler_options) { {} }
     let(:template) { 'template.rb' }
@@ -104,17 +104,17 @@ def compile
 
     context 'with sparkle packs' do
       let(:compile_time_parameters) { {} }
-      let(:compiler_options) { { "sparkle_packs" => ["my_sparkle_pack"] } }
+      let(:compiler_options) { { 'sparkle_packs' => ['my_sparkle_pack'] } }
 
       before do
-        lib = File.join(File.dirname(__FILE__), "..", "..", "fixtures", "sparkle_pack_integration", "my_sparkle_pack",
-                        "lib")
+        lib = File.join(File.dirname(__FILE__), '..', '..', 'fixtures', 'sparkle_pack_integration', 'my_sparkle_pack',
+                        'lib')
         $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
       end
 
       context 'compiling a sparkle pack dynamic' do
         let(:template) { 'template_with_dynamic_from_pack' }
-        let(:compiler_options) { { "sparkle_packs" => ["my_sparkle_pack"], "sparkle_pack_template" => true } }
+        let(:compiler_options) { { 'sparkle_packs' => ['my_sparkle_pack'], 'sparkle_pack_template' => true } }
 
         it 'pulls the dynamic from the sparkle pack' do
           expect(compile).to eq(<<~JSON.chomp)
@@ -131,7 +131,7 @@ def compile
 
       context 'compiling a sparkle pack template' do
         let(:template) { 'template_with_dynamic' }
-        let(:compiler_options) { { "sparkle_packs" => ["my_sparkle_pack"], "sparkle_pack_template" => true } }
+        let(:compiler_options) { { 'sparkle_packs' => ['my_sparkle_pack'], 'sparkle_pack_template' => true } }
 
         context 'when template is found' do
           it 'resolves template location' do
diff --git a/spec/stack_master/template_compilers/yaml_spec.rb b/spec/stack_master/template_compilers/yaml_spec.rb
index fd19f4ff..c6119d94 100644
--- a/spec/stack_master/template_compilers/yaml_spec.rb
+++ b/spec/stack_master/template_compilers/yaml_spec.rb
@@ -7,10 +7,10 @@ def compile
     end
 
     context 'valid YAML template' do
-      let(:stack_definition) {
+      let(:stack_definition) do
         StackMaster::StackDefinition.new(template_dir: 'spec/fixtures/templates/yml',
                                          template: 'valid_myapp_vpc.yml')
-      }
+      end
 
       it 'produces valid YAML' do
         valid_myapp_vpc_yaml = File.read(stack_definition.template_file_path)
diff --git a/spec/stack_master/template_utils_spec.rb b/spec/stack_master/template_utils_spec.rb
index a9611dc3..37ce07fd 100644
--- a/spec/stack_master/template_utils_spec.rb
+++ b/spec/stack_master/template_utils_spec.rb
@@ -1,31 +1,31 @@
 RSpec.describe StackMaster::TemplateUtils do
-  describe "#identify_template_format" do
+  describe '#identify_template_format' do
     subject { described_class.identify_template_format(template_body) }
 
-    context "with a json template body" do
+    context 'with a json template body' do
       let(:template_body) { '{"AWSTemplateFormatVersion": "2010-09-09"}' }
 
       it { is_expected.to eq(:json) }
 
-      context "starting with a blank line with whitespace" do
+      context 'starting with a blank line with whitespace' do
         let(:template_body) { "\n " + '{"AWSTemplateFormatVersion" : "2010-09-09"}' }
 
         it { is_expected.to eq(:json) }
       end
     end
 
-    context "with a non-json template body" do
+    context 'with a non-json template body' do
       let(:template_body) { 'AWSTemplateFormatVersion: 2010-09-09' }
 
       it { is_expected.to eq(:yaml) }
     end
   end
 
-  describe "#maybe_compressed_template_body" do
+  describe '#maybe_compressed_template_body' do
     subject(:maybe_compressed_template_body) do
       described_class.maybe_compressed_template_body(template_body)
     end
-    context "undersized json" do
+    context 'undersized json' do
       let(:template_body) { '{     }' }
 
       it "leaves the json alone if it's not too large" do
@@ -33,8 +33,8 @@
       end
     end
 
-    context "oversized json" do
-      let(:template_body) { "{#{' ' * 60000}}" }
+    context 'oversized json' do
+      let(:template_body) { "{#{' ' * 60_000}}" }
       it "compresses the json when it's overly bulbous" do
         expect(maybe_compressed_template_body).to eq('{}')
       end
diff --git a/spec/stack_master/test_driver/cloud_formation_spec.rb b/spec/stack_master/test_driver/cloud_formation_spec.rb
index c13f4b57..91608288 100644
--- a/spec/stack_master/test_driver/cloud_formation_spec.rb
+++ b/spec/stack_master/test_driver/cloud_formation_spec.rb
@@ -5,17 +5,17 @@
 
   context 'stacks' do
     it 'creates and describes stacks' do
-      test_cf_driver.create_stack(stack_id: "1", stack_name: 'stack-1')
-      test_cf_driver.create_stack(stack_id: "2", stack_name: 'stack-2')
-      expect(test_cf_driver.describe_stacks.stacks.map(&:stack_id)).to eq(["1", "2"])
+      test_cf_driver.create_stack(stack_id: '1', stack_name: 'stack-1')
+      test_cf_driver.create_stack(stack_id: '2', stack_name: 'stack-2')
+      expect(test_cf_driver.describe_stacks.stacks.map(&:stack_id)).to eq(%w[1 2])
     end
 
     it 'adds and gets stack events' do
-      test_cf_driver.add_stack_event(stack_name: 'stack-1', resource_status: "UPDATE_COMPLETE")
-      test_cf_driver.add_stack_event(stack_name: 'stack-1', resource_status: "UPDATE_COMPLETE")
+      test_cf_driver.add_stack_event(stack_name: 'stack-1', resource_status: 'UPDATE_COMPLETE')
+      test_cf_driver.add_stack_event(stack_name: 'stack-1', resource_status: 'UPDATE_COMPLETE')
       test_cf_driver.add_stack_event(stack_name: 'stack-2')
       expect(test_cf_driver.describe_stack_events(stack_name: 'stack-1').stack_events.map(&:stack_name))
-        .to eq(['stack-1', 'stack-1'])
+        .to eq(%w[stack-1 stack-1])
     end
 
     it 'sets and gets templates' do
@@ -59,15 +59,15 @@
       )
       test_cf_driver.execute_change_set(change_set_name: change_set1.id)
       test_cf_driver.execute_change_set(change_set_name: change_set2.id)
-      expect(test_cf_driver.describe_stacks.stacks.map(&:stack_name)).to eq(['stack-1', 'stack-2'])
+      expect(test_cf_driver.describe_stacks.stacks.map(&:stack_name)).to eq(%w[stack-1 stack-2])
     end
   end
 
   it 'deletes change sets' do
     change_set_id = test_cf_driver.create_change_set(stack_name: '1', change_set_name: '2').id
     test_cf_driver.delete_change_set(change_set_name: change_set_id)
-    expect {
+    expect do
       test_cf_driver.describe_change_set(change_set_name: change_set_id)
-    }.to raise_error(KeyError)
+    end.to raise_error(KeyError)
   end
 end
diff --git a/spec/stack_master/utils_spec.rb b/spec/stack_master/utils_spec.rb
index 3076c34e..c63dc45f 100644
--- a/spec/stack_master/utils_spec.rb
+++ b/spec/stack_master/utils_spec.rb
@@ -1,26 +1,26 @@
 RSpec.describe StackMaster::Utils do
-  describe ".hash_to_aws_tags" do
+  describe '.hash_to_aws_tags' do
     let(:tags) { { 'environment' => 'production' } }
     subject(:aws_tags) { StackMaster::Utils.hash_to_aws_tags(tags) }
 
-    it "converts the tags attribute to aws format" do
+    it 'converts the tags attribute to aws format' do
       expect(aws_tags).to eq([{ key: 'environment', value: 'production' }])
     end
 
-    context "tags is nil" do
+    context 'tags is nil' do
       let(:tags) { nil }
 
-      it "returns nil" do
+      it 'returns nil' do
         expect(aws_tags).to eq([])
       end
     end
   end
 
-  describe ".hash_to_aws_parameters" do
+  describe '.hash_to_aws_parameters' do
     let(:params) { { 'param1' => 'value1', 'param2' => 'value2' } }
     subject(:aws_params) { StackMaster::Utils.hash_to_aws_parameters(params) }
 
-    it "converts to aws parameters" do
+    it 'converts to aws parameters' do
       expect(aws_params).to eq(
         [
           { parameter_key: 'param1', parameter_value: 'value1' },
diff --git a/spec/stack_master/validator_spec.rb b/spec/stack_master/validator_spec.rb
index 31351abd..60922fef 100644
--- a/spec/stack_master/validator_spec.rb
+++ b/spec/stack_master/validator_spec.rb
@@ -10,7 +10,7 @@
       stack_name: stack_name,
       template: template_file,
       tags: { 'environment' => 'production' },
-      base_dir: File.expand_path('spec/fixtures'),
+      base_dir: File.expand_path('spec/fixtures')
     )
   end
   let(:cf) { spy(Aws::CloudFormation::Client, validate_template: nil) }
@@ -25,32 +25,32 @@
     allow(StackMaster::ParameterResolver).to receive(:resolve).and_return(resolved_parameters)
   end
 
-  describe "#perform" do
-    context "template body is valid" do
-      it "tells the user everything will be fine" do
+  describe '#perform' do
+    context 'template body is valid' do
+      it 'tells the user everything will be fine' do
         expect { validator.perform }.to output(/myapp_vpc: valid/).to_stdout
       end
     end
 
-    context "invalid template body" do
+    context 'invalid template body' do
       before do
         allow(cf)
           .to receive(:validate_template)
           .and_raise(Aws::CloudFormation::Errors::ValidationError.new('a', 'Problem'))
       end
 
-      it "informs the user of their stupdity" do
+      it 'informs the user of their stupdity' do
         expect { validator.perform }.to output(/myapp_vpc: invalid/).to_stdout
       end
     end
 
-    context "missing parameters" do
+    context 'missing parameters' do
       let(:template_file) { 'mystack-with-parameters.yaml' }
 
-      context "--validate-template-parameters" do
+      context '--validate-template-parameters' do
         before { options.validate_template_parameters = true }
 
-        it "informs the user of the problem" do
+        it 'informs the user of the problem' do
           expect { validator.perform }.to output(<<~OUTPUT).to_stdout
             myapp_vpc: invalid
             Empty/blank parameters detected. Please provide values for these parameters:
@@ -63,10 +63,10 @@
         end
       end
 
-      context "--no-validate-template-parameters" do
+      context '--no-validate-template-parameters' do
         before { options.validate_template_parameters = false }
 
-        it "reports the stack as valid" do
+        it 'reports the stack as valid' do
           expect { validator.perform }.to output(/myapp_vpc: valid/).to_stdout
         end
       end
diff --git a/spec/stack_master_spec.rb b/spec/stack_master_spec.rb
index c2b7c4f6..fd4ec22c 100644
--- a/spec/stack_master_spec.rb
+++ b/spec/stack_master_spec.rb
@@ -1,6 +1,6 @@
 RSpec.describe StackMaster do
   describe '.debug' do
-    let(:message) { "Doing some stuff" }
+    let(:message) { 'Doing some stuff' }
 
     context 'when debugging' do
       before { allow(StackMaster).to receive(:debug?).and_return(true) }
@@ -14,7 +14,7 @@
       before { allow(StackMaster).to receive(:debug?).and_return(false) }
 
       it "doesn't output the message to STDERR" do
-        expect { StackMaster.debug(message) }.to output("").to_stderr
+        expect { StackMaster.debug(message) }.to output('').to_stderr
       end
     end
   end
diff --git a/spec/support/aws_stubs.rb b/spec/support/aws_stubs.rb
index 7b90e294..468eb10a 100644
--- a/spec/support/aws_stubs.rb
+++ b/spec/support/aws_stubs.rb
@@ -1,16 +1,16 @@
 Aws.config[:stub_responses] = true
 
 module AwsHelpers
-  def stub_drift_detection(stack_drift_detection_id: "1", stack_drift_status: "IN_SYNC")
+  def stub_drift_detection(stack_drift_detection_id: '1', stack_drift_status: 'IN_SYNC')
     cfn.stub_responses(:detect_stack_drift, { stack_drift_detection_id: stack_drift_detection_id })
     cfn.stub_responses(
       :describe_stack_drift_detection_status,
       {
-        stack_id: "1",
+        stack_id: '1',
         timestamp: Time.now,
         stack_drift_detection_id: stack_drift_detection_id,
         stack_drift_status: stack_drift_status,
-        detection_status: "DETECTION_COMPLETE"
+        detection_status: 'DETECTION_COMPLETE'
       }
     )
   end
diff --git a/stack_master.gemspec b/stack_master.gemspec
index 22ae8e92..02cd5a27 100644
--- a/stack_master.gemspec
+++ b/stack_master.gemspec
@@ -1,66 +1,64 @@
-# coding: utf-8
-
-lib = File.expand_path('../lib', __FILE__)
+lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'stack_master/version'
 require 'rbconfig'
 
 Gem::Specification.new do |spec|
-  spec.name          = "stack_master"
+  spec.name          = 'stack_master'
   spec.version       = StackMaster::VERSION
-  spec.authors       = ["Steve Hodgkiss", "Glen Stampoultzis"]
-  spec.email         = ["steve@hodgkiss.me", "gstamp@gmail.com"]
+  spec.authors       = ['Steve Hodgkiss', 'Glen Stampoultzis']
+  spec.email         = ['steve@hodgkiss.me', 'gstamp@gmail.com']
   spec.summary       = 'StackMaster is a sure-footed way of creating, updating and keeping track ' \
                        'of Amazon (AWS) CloudFormation stacks.'
-  spec.description   = %q{}
-  spec.homepage      = "https://opensource.envato.com/projects/stack_master.html"
-  spec.license       = "MIT"
+  spec.description   = ''
+  spec.homepage      = 'https://opensource.envato.com/projects/stack_master.html'
+  spec.license       = 'MIT'
   spec.metadata      = {
-    "bug_tracker_uri" => "https://github.com/envato/stack_master/issues",
-    "changelog_uri" => "https://github.com/envato/stack_master/blob/master/CHANGELOG.md",
-    "documentation_uri" => "https://www.rubydoc.info/gems/stack_master/#{spec.version}",
-    "source_code_uri" => "https://github.com/envato/stack_master/tree/v#{spec.version}",
+    'bug_tracker_uri' => 'https://github.com/envato/stack_master/issues',
+    'changelog_uri' => 'https://github.com/envato/stack_master/blob/master/CHANGELOG.md',
+    'documentation_uri' => "https://www.rubydoc.info/gems/stack_master/#{spec.version}",
+    'source_code_uri' => "https://github.com/envato/stack_master/tree/v#{spec.version}"
   }
 
-  spec.files         = Dir.glob("{bin,lib,stacktemplates}/**/*") + %w(README.md LICENSE.txt)
+  spec.files         = Dir.glob('{bin,lib,stacktemplates}/**/*') + %w[README.md LICENSE.txt]
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
-  spec.require_paths = ["lib"]
-  spec.required_ruby_version = ">= 2.4.0"
+  spec.require_paths = ['lib']
+  spec.required_ruby_version = '>= 2.4.0'
 
-  spec.add_development_dependency "bundler"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "rspec"
-  spec.add_development_dependency "pry"
-  spec.add_development_dependency "cucumber"
-  spec.add_development_dependency "aruba"
-  spec.add_development_dependency "timecop"
-  spec.add_development_dependency "ostruct"
-  spec.add_development_dependency "rubocop"
-  spec.add_dependency "os"
-  spec.add_dependency "ruby-progressbar"
-  spec.add_dependency "commander", ">= 4.6.0", "< 6"
-  spec.add_dependency "aws-sdk-acm", "~> 1"
-  spec.add_dependency "aws-sdk-cloudformation", "~> 1"
-  spec.add_dependency "aws-sdk-ec2", "~> 1"
-  spec.add_dependency "aws-sdk-identitystore", "~> 1"
-  spec.add_dependency "aws-sdk-s3", "~> 1"
-  spec.add_dependency "aws-sdk-sns", "~> 1"
-  spec.add_dependency "aws-sdk-ssm", "~> 1"
-  spec.add_dependency "aws-sdk-ecr", "~> 1"
-  spec.add_dependency "aws-sdk-iam", "~> 1"
-  spec.add_dependency "sorted_set" # remove once new version of sparkle_formation released (> v3.0.40). See https://github.com/sparkleformation/sparkle_formation/pull/271.
-  spec.add_dependency "diffy"
-  spec.add_dependency "erubis"
-  spec.add_dependency "rainbow"
-  spec.add_dependency "activesupport", '>= 4'
-  spec.add_dependency "sparkle_formation", "~> 3"
-  spec.add_dependency "table_print"
-  spec.add_dependency "deep_merge"
-  spec.add_dependency "cfndsl", "~> 1"
-  spec.add_dependency "multi_json"
-  spec.add_dependency "hashdiff", "~> 1"
-  spec.add_dependency "ejson_wrapper"
-  spec.add_dependency "diff-lcs"
-  spec.add_dependency "cfn-nag", ">= 0.6.7", "< 0.9.0"
+  spec.add_development_dependency 'bundler'
+  spec.add_development_dependency 'rake'
+  spec.add_development_dependency 'rspec'
+  spec.add_development_dependency 'pry'
+  spec.add_development_dependency 'cucumber'
+  spec.add_development_dependency 'aruba'
+  spec.add_development_dependency 'timecop'
+  spec.add_development_dependency 'ostruct'
+  spec.add_development_dependency 'rubocop'
+  spec.add_dependency 'os'
+  spec.add_dependency 'ruby-progressbar'
+  spec.add_dependency 'commander', '>= 4.6.0', '< 6'
+  spec.add_dependency 'aws-sdk-acm', '~> 1'
+  spec.add_dependency 'aws-sdk-cloudformation', '~> 1'
+  spec.add_dependency 'aws-sdk-ec2', '~> 1'
+  spec.add_dependency 'aws-sdk-identitystore', '~> 1'
+  spec.add_dependency 'aws-sdk-s3', '~> 1'
+  spec.add_dependency 'aws-sdk-sns', '~> 1'
+  spec.add_dependency 'aws-sdk-ssm', '~> 1'
+  spec.add_dependency 'aws-sdk-ecr', '~> 1'
+  spec.add_dependency 'aws-sdk-iam', '~> 1'
+  spec.add_dependency 'sorted_set' # remove once new version of sparkle_formation released (> v3.0.40). See https://github.com/sparkleformation/sparkle_formation/pull/271.
+  spec.add_dependency 'diffy'
+  spec.add_dependency 'erubis'
+  spec.add_dependency 'rainbow'
+  spec.add_dependency 'activesupport', '>= 4'
+  spec.add_dependency 'sparkle_formation', '~> 3'
+  spec.add_dependency 'table_print'
+  spec.add_dependency 'deep_merge'
+  spec.add_dependency 'cfndsl', '~> 1'
+  spec.add_dependency 'multi_json'
+  spec.add_dependency 'hashdiff', '~> 1'
+  spec.add_dependency 'ejson_wrapper'
+  spec.add_dependency 'diff-lcs'
+  spec.add_dependency 'cfn-nag', '>= 0.6.7', '< 0.9.0'
 end