.github/workflows/apidiff.yml

---
name: apidiff
on:
  pull_request:

permissions:
  contents: read

jobs:
  scan_changes:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
      with:
        ref: main
    - name: Get main commit
      id: main
      run: echo "hash=$(git rev-parse HEAD)" >> $GITHUB_OUTPUT
    - uses: actions/checkout@v4
    - uses: actions/setup-go@v5
      with:
        go-version: '1.22.x'
    - name: Get changed directories
      id: changed_dirs
      # Ignore changes to the internal and root directories.
      # Ignore added files with --diff-filter=a.
      run: |
        dirs=$(go run ./internal/actions/cmd/changefinder -q --diff-filter=a)
        if [ -z "$dirs" ]
        then
          echo "skip=1" >> $GITHUB_OUTPUT
          echo "No changes worth diffing!"
        else
          for d in $dirs; do list=${list},\"${d}\"; done
          echo "changed={\"changed\":[${list#,}]}" >> $GITHUB_OUTPUT
          echo "skip=" >> $GITHUB_OUTPUT
        fi
    outputs:
      changed_dirs: ${{ steps.changed_dirs.outputs.changed }}
      skip: ${{ steps.changed_dirs.outputs.skip }}
  apidiff:
    needs: scan_changes
    runs-on: ubuntu-latest
    if: ${{ !needs.scan_changes.outputs.skip && !contains(github.event.pull_request.labels.*.name, 'breaking change allowed') }}
    continue-on-error: true
    permissions:
      pull-requests: write
    strategy:
      matrix: ${{ fromJson(needs.scan_changes.outputs.changed_dirs) }}
    steps:
    - uses: actions/setup-go@v5
      with:
        go-version: '1.22.x'
    - name: Install latest apidiff
      run: go install golang.org/x/exp/cmd/apidiff@latest
    - uses: actions/checkout@v4
      with:
        ref: main
    - name: Create baseline
      id: baseline
      run: |
        export CHANGED=${{ matrix.changed }}
        echo pkg="${CHANGED//\//_}_pkg.main" >> $GITHUB_OUTPUT
    - name: Create Go package baseline
      run: cd ${{ matrix.changed }} && apidiff -m -w ${{ steps.baseline.outputs.pkg }} .
    - name: Upload baseline package data
      uses: actions/upload-artifact@v4
      with:
        name: ${{ steps.baseline.outputs.pkg }}
        path: ${{ matrix.changed }}/${{ steps.baseline.outputs.pkg }}
        retention-days: 1
    - uses: actions/checkout@v4
    - name: Download baseline package data
      uses: actions/download-artifact@v4
      with:
        name: ${{ steps.baseline.outputs.pkg }}
        path: ${{ matrix.changed }}
    - name: Compare regenerated code to baseline
      # Only ignore Go interface additions when the PR is from OwlBot as it is
      # likely a new method added to the gRPC client stub interface, which is
      # non-breaking.
      env:
        PR_HEAD_REF: ${{ github.event.pull_request.head.ref }}
      run: |
        cd ${{ matrix.changed }} && apidiff -m -incompatible ${{ steps.baseline.outputs.pkg }} . > diff.txt
        if [[ "$PR_HEAD_REF" == owl-bot-copy ]]; then
          sed -i '/: added/d' ./diff.txt
        fi
        cat diff.txt && ! [ -s diff.txt ]
    - name: Add breaking change label
      if: ${{ failure() && !github.event.pull_request.head.repo.fork }}
      uses: actions/github-script@v7
      with:
        script: |
          github.rest.issues.addLabels({
            issue_number: ${{ github.event.number }},
            owner: context.repo.owner,
            repo: context.repo.repo,
            labels: ['breaking change']
          })