On branch update

.github/dependency_filters.yml

@@ -0,0 +1,9 @@
+dependencies:
+  - Gemfile
+  - Appraisals
+  - datadog.gemspec
+  - tasks/appraisal.rake
+  - .github/workflows/lock-dependency.yml
+  - lib/datadog/version.rb
+  - appraisal/**
+  - gemfiles/**

.github/workflows/lock-dependency.yml

@@ -1,26 +1,65 @@
 name: Lock Dependency
 
+# TODO: Make this job mandatory
+# TODO: Make this on workflow_dispatch
+
 on:
-  workflow_dispatch:
-    inputs:
-      branch:
-        description: 'Branch to be lock dependency'
-        required: true
-  # Testing purpose, to be removed before merge.
+  # Limitation about `paths` types:
+  # > https://docs.github.com/en/actions/writing-workflows/workflow-syntax-for-github-actions#git-diff-comparisons
   push:
-    branches:
-      - tonycthsu/automate-update-gemfiles
+    branches-ignore:
+      - master
+      - release
+      - '*-stable'
+  pull_request:
+    # Run this job when a PR is opened, covering the scenario where branch is ready and pushed before PR is opened.
+    types:
+      - opened
+
 
-# Ensure obsolete job is cancelled if another commit is pushed to the same branch.
+# TODO: Improve concurrency between push event and pull_request event
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
 jobs:
-  # TODO: In order to fully automate this workflow for each PR,
-  # have a reliable way to precheck job to understand whether it need to be updated
+  pr:
+    name: Pull Request attached
+    runs-on: ubuntu-latest
+    outputs:
+      pr_found: ${{ steps.pr.outputs.pr_found }}
+      pr_base_ref: ${{ steps.pr.outputs.pr.base.ref }}
+    steps:
+      # Limitation with pull_request trigger: https://github.com/8BitJonny/gh-get-current-pr/tree/3.0.0/?tab=readme-ov-file#limitations
+      - uses: 8BitJonny/gh-get-current-pr@3.0.0
+        id: pr
+        with:
+          filterOutClosed: true # Don't trigger on commits with closed PRs, including merges into `master`.
+
+  dependency:
+    name: Depenedency changes
+    needs: pr
+    if: ${{ needs.pr.outputs.pr_found == 'true' }}
+    runs-on: ubuntu-latest
+    outputs:
+      changes: ${{ steps.changes.outputs.dependencies }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dorny/paths-filter@v3
+        id: changes
+        with:
+          # This is the best effort to get the diff comparison.
+          # The result remains time-sensitive since the `base` is constantly changing and
+          # the PR cannot be guaranteed to be up-to-date.
+          #
+          # Unless enable `Require branches to be up to date before merging` in the repository rule settings
+          base: ${{ needs.pr.outputs.pr_base_ref }}
+          filters: .github/dependency_filters.yml
+
   lock:
     runs-on: ubuntu-latest
+    needs: dependency
+    if: ${{ needs.dependency.outputs.changes == 'true' }}
     strategy:
       fail-fast: false
       matrix:
@@ -54,39 +93,35 @@ jobs:
         BUNDLE_WITHOUT: check
     steps:
       - uses: actions/checkout@v4
-      - run: ls -al
       - run: |
           ruby -v
           gem -v
           bundler -v
-
       - run: bundle install
 
       # TODO: Migrate away from `appraisal`
       - run: bundle exec appraisal generate
       - run: bundle exec rake dependency:lock
-
       - uses: actions/upload-artifact@v4
         with:
           name: lock-dependency-${{ github.run_id }}-${{ matrix.engine.name }}-${{ matrix.engine.version }}
           path: gemfiles/${{ matrix.engine.name }}_${{ matrix.engine.version }}*
 
+  # TODO: Change token to trigger workflow automation
+  # > New commit by GITHUB_TOKEN does not trigger workflow automation to prevent infinite loop
   commit:
+    name: Commit changes
     needs: lock
     runs-on: ubuntu-latest
     permissions:
       contents: write
     steps:
       - uses: actions/checkout@v4
-
       - uses: actions/download-artifact@v4
         with:
           path: gemfiles
           pattern: lock-dependency-${{ github.run_id }}-*
           merge-multiple: true
-
-      - run: git diff --color
-
       - uses: stefanzweifel/git-auto-commit-action@v5
         with:
           file_pattern: 'gemfiles/*'

.github/workflows/update-gemfiles.yml

@@ -0,0 +1,83 @@
+name: Update Gemfiles
+
+# This action cannot be skipped altogether because it is a mandatory status check.
+# Instead we conditionally skip it at job level, instead of workflow level.
+on:
+  # Execute on `push` and not `pull_request` because `pull_request`
+  # always compares if the `paths` have changed compared to the PR base.
+  # This is an issue because it means that all commits to the branch
+  # will trigger the gemfile update process, which is unnecessary and expensive.
+  #
+  # By executing on `push`, GitHub compares `paths` with the parent commit,
+  # meaning the gemfile update process will only execute on the exact commit
+  # that changes any of the `paths`.
+  #
+  # Because this process is slow and expensive, and we commit the gemfile changes back
+  # to the branch, we have an additional filter to only execute this action on branches
+  # attached to a PR.
+  #
+  # We could do the inverse: execute this action on `pull_request`, and additionally check
+  # if `paths` was changed compared to the parent commit, but this proved more complicated.
+  push
+
+# Ensure obsolete job is cancelled if another commit is pushed to the same branch.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    name: Update Gemfiles
+    runs-on: ubuntu-22.04
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      # Only execute if there's a PR attached to this branch.
+      # Because we execute on `push`, we have to double check here if this is part of a PR.
+      - name: Check if this branch is attached to a Pull Request
+        uses: 8bitjonny/gh-get-current-pr@2215326c76d51bfa3f2af0a470f32677f6c0cae9 # v2.2.0
+        id: pr
+        with:
+          filterOutClosed: true # Don't trigger on commits with closed PRs, including merges into `master`.
+      - if: steps.pr.outputs.pr_found == 'true'
+        uses: actions/checkout@v4
+      # And also, only execute if files that can affect gemfiles are modified.
+      - if: steps.pr.outputs.pr_found == 'true'
+        uses: dorny/paths-filter@4512585405083f25c027a35db413c2b3b9006d50 # v2.11.1
+        id: filter
+        with:
+          base: ${{ github.ref_name }}
+          filters: |
+            gemfile:
+              # Files that declare the dependency tree
+              - Gemfile
+              - Appraisals
+              - datadog.gemspec
+              # Files that control gemfile generation
+              - tasks/appraisal.rake
+              - .github/workflows/update-gemfiles.yml
+              # The gem version is present in all lock files
+              - lib/datadog/version.rb
+              # In case the generated files were updated manually or in a merge commit
+              - appraisal/**
+              - gemfiles/**
+      - if: steps.pr.outputs.pr_found == 'true' && steps.filter.outputs.gemfile == 'true'
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.2'
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - if: steps.pr.outputs.pr_found == 'true' && steps.filter.outputs.gemfile == 'true'
+        name: Ensure gemfiles/*.gemfile.lock match gem definition
+        run: bundle exec rake appraisal:lock
+      - if: steps.pr.outputs.pr_found == 'true' && steps.filter.outputs.gemfile == 'true'
+        name: Add all supported platforms to gemfiles/*.gemfile.lock
+        run: bundle exec rake appraisal:platform
+      - if: steps.pr.outputs.pr_found == 'true' && steps.filter.outputs.gemfile == 'true'
+        name: Remove obsolete gemfiles/*
+        run: bundle exec rake appraisal:clean
+      - if: steps.pr.outputs.pr_found == 'true' && steps.filter.outputs.gemfile == 'true'
+        name: Commit gemfiles changes, if any, back to the branch
+        uses: stefanzweifel/git-auto-commit-action@3ea6ae190baf489ba007f7c92608f33ce20ef04a # v4.16.0
+        with:
+          commit_message: Update gemfiles/*