Add --max-log-lines option to set # of items to print per section

Add an optional CLI option --max-log-lines for setting the number of
lines of build info to print for each section. All other lines in that
section will be hidden and "+ X more" will be displayed instead. This
prevents the log from becoming too long when working on apps with
thousands of pages.

The option defaults to showing 50 lines per build section: 50 lines for
SSR pages, 50 lines for SSG pages, 50 lines of redirects, ...

See: #26

Author: FinnWoelm

lib/logger.js

@@ -1,17 +1,46 @@
 // Helpers for writing info to console.log
+const { program } = require('commander')
+
+// Number of items processed in current build step
+let itemsCount = 0
 
 // Format in bold
-const logTitle = (...args) =>
+const logTitle = (...args) => {
+  // Finish previous log section
+  finishLogForBuildStep()
+
+  // Print title
   log(`\x1b[1m${args.join(" ")}\x1b[22m`)
+}
 
 // Indent by three spaces
-const logItem = (...args) =>
-  log('  ', ...args)
+const logItem = (...args) => {
+  // Display item if within max log lines
+  if(itemsCount < program.maxLogLines)
+    log('  ', ...args)
+
+  itemsCount += 1
+}
 
 // Just console.log
 const log = (...args) =>
   console.log(...args)
 
+// Finish log section: Write a single line for any suppressed/hidden items
+// and reset the item counter
+const finishLogForBuildStep = () => {
+  // Display number of suppressed log lines
+  if(itemsCount > program.maxLogLines) {
+    const hiddenLines = itemsCount - program.maxLogLines
+    log('  ', '+', hiddenLines, 'more',
+        '(run next-on-netlify with --max-log-lines XX to',
+        'show more or fewer lines)')
+  }
+
+  // Reset counter
+  itemsCount = 0
+}
+
 module.exports = {
   logTitle,
   logItem,

next-on-netlify.js

@@ -1,4 +1,9 @@
 #!/usr/bin/env node
+const { program } = require('commander')
+
+program
+  .option('--max-log-lines [number]', 'lines of build output to show for each section', 50)
+  .parse(process.argv)
 
 const { logTitle } = require('./lib/logger')
 const prepareFolders  = require('./lib/prepareFolders')

package-lock.json

@@ -45,6 +45,7 @@
   },
   "dependencies": {
     "@sls-next/lambda-at-edge": "^1.5.2",
+    "commander": "^6.0.0",
     "fs-extra": "^9.0.1",
     "next-aws-lambda": "^2.5.0"
   }