Provide support for input parameters in the CreateStack and UpdateStack procedures

[urvashisingh]

The current implementations of CreateStack and UpdateStack do not support passing values for the input parameters defined in a Heat Orchestration template file. This means that users cannot take true advantage of the template feature as they will need to have the actual values specified in the template itself. Here is a simple example using input parameters where the key-pair name, image-id and the instance_type are defined as input parameters.

heat_template_version: 2013-05-23

description: Simple template to deploy a single compute instance

parameters:
key_name:
type: string
label: Key Name
description: Name of key-pair to be used for compute instance
image_id:
type: string
label: Image ID
description: Image to be used for compute instance
instance_type:
type: string
label: Instance Type
description: Type of instance (flavor) to be used

resources:
my_instance:
type: OS::Nova::Server
properties:
key_name: { get_param: key_name }
image: { get_param: image_id }
flavor: { get_param: instance_type }

The same template above can be used to create different types of instances by passing different values for the image_id and instance_type. One can imagine this being used to create staging versus testing versus production stacks using different system configurations but the same template.