[build] Skip CI jobs if there are no relevant changed files

1 files changed, 121 insertions, 0 deletions

diff --git a/scripts/check-ci-job-skippability.js b/scripts/check-ci-job-skippability.js
new file mode 100755
index 0000000000..55f940db31
--- /dev/null
+++ b/scripts/check-ci-job-skippability.js
@@ -0,0 +1,121 @@
+#!/usr/bin/env node
+
+/*
+This script takes two parameters or three environment variables:
+
+  {CI job name|$CIRCLE_JOB} {SHA1...SHA1|$CIRCLE_MERGE_BASE...$CIRCLE_SHA1}
+
+The flow of this script:
+
+  - List of files changed in PR: `git diff --name-only start...end`
+  - Extract list into array.
+  - Remove items from array if they match:
+    - Global ignore list.
+    - Other platform ignore lists.
+  - If array still contains items, do not authorize skipping CI job.
+  - Else if array is empty, skip CI job.
+
+To add support for a new platform:
+
+  - Add a new PLATFORM_FILES array with a list of unique paths for the
+    files belonging to the platform.
+  - Add a case to `skippableFilePatternsForCIJob()` with:
+    - The prefix for the platform's CI job names.
+    - A concatenated array of other platform paths that are safe to ignore
+      for the new platform. These should be files that can change without
+      having any effect on the output of the new platform.
+  - Update other cases in `skippableFilePatternsForCIJob()` to include the
+    paths for the new platform.
+*/
+
+const execSync = require('child_process').execSync;
+const _ = require('lodash');
+const minimatch = require("minimatch");
+
+console.step = _.partial(console.log, '\n\033[1m\033[36m*', _, '\033[0m');
+
+// BUILD PARAMETERS
+const CI_JOB_NAME = process.argv[2] || process.env.CIRCLE_JOB;
+if (!CI_JOB_NAME) { console.error('You must specify the name of a CI job as a parameter or environment variable.'); process.exit(1); }
+
+const COMMIT_RANGE = process.argv[3] || `${process.env.CIRCLE_MERGE_BASE}...${process.env.CIRCLE_SHA1}`;
+if (!COMMIT_RANGE || COMMIT_RANGE.includes('undefined')) { console.error('You must specify a range of commits to check for changed files in as a parameter or environment variable.'); process.exit(1); }
+
+// FILE SKIPPING PATTERNS
+const ALWAYS_SKIPPABLE_FILES = [
+  '**/CHANGELOG.md',
+  '**/README.md',
+  '**/CONTRIBUTING.md',
+  '**/DEVELOPING.md',
+  '**/INSTALL.md',
+  '**/*.podspec'
+]
+
+const ANDROID_FILES = [
+  'platform/android/**'
+]
+
+const DARWIN_FILES = [
+  'platform/darwin/**'
+]
+
+const IOS_FILES = [
+  'platform/ios/**'
+]
+
+const MACOS_FILES = [
+  'platform/macos/**'
+]
+
+const OTHER_PLATFORMS = [
+  'platform/glfw/**',
+  'platform/linux/**',
+  'platform/node/**',
+  'platform/qt/**',
+  'benchmark/**',
+  'test/**'
+]
+
+function skippableFilePatternsForCIJob(job) {
+  if (job.includes('render-tests')) {
+      // Render tests run on specific platforms are effectively unskippable core jobs, not platform jobs.
+      return ALWAYS_SKIPPABLE_FILES;
+  } else if (job.startsWith('ios')) {
+      return _.concat(ALWAYS_SKIPPABLE_FILES, ANDROID_FILES, MACOS_FILES, OTHER_PLATFORMS);
+  } else if (job.startsWith('android')) {
+      return _.concat(ALWAYS_SKIPPABLE_FILES, DARWIN_FILES, IOS_FILES, MACOS_FILES, OTHER_PLATFORMS);
+  } else if (job.startsWith('macos')) {
+      return _.concat(ALWAYS_SKIPPABLE_FILES, ANDROID_FILES, IOS_FILES, OTHER_PLATFORMS);
+  } else {
+      return ALWAYS_SKIPPABLE_FILES;
+  }
+}
+
+console.step(`Getting list of files changed between ${COMMIT_RANGE}`);
+
+let changedFiles = execSync(`git diff --name-only ${COMMIT_RANGE}`).toString().split('\n');
+changedFiles = _.compact(changedFiles);
+
+console.log(`${changedFiles.length} total files changed.`);
+
+console.step(`Checking changed files for paths relevant to ${CI_JOB_NAME} job`);
+
+// Filter the changed files array to remove files that are irrelevant to the specified CI job.
+_.remove(changedFiles, function(changedFile) {
+  for (const skippableFilePattern of skippableFilePatternsForCIJob(CI_JOB_NAME)) {
+    if (minimatch(changedFile, skippableFilePattern, { dot: true, nocase: true })) {
+      return true;
+    }
+  }
+  return false;
+});
+
+if (changedFiles.length) {
+  console.log(`Found ${changedFiles.length} unskippable changed file${changedFiles.length > 1 ? 's':''}:\n`, changedFiles);
+} else {
+  console.log(`Found no relevant changed files, so it's safe to skip the remainder of this CI job.`)
+  if (process.env.CIRCLECI) {
+    console.step('Aborting CI job');
+    execSync(`circleci step halt`, {stdio: 'inherit'});
+  }
+}