generate-api-diff-baseline.yml

---
name: Generate API Diff Baseline

# When Renovate bumps <api.diff.baseline.version> (on the renovate/api-diff-baseline
# branch), regenerate docs/apidiffs against the new baseline and push the result
# back onto the PR. Renovate only proposes versions already published to Maven
# Central, so japicmp can always resolve the new baseline.
#
# Before regenerating, the previous current_vs_latest is archived as
# docs/apidiffs/<new>_vs_<old>/ to keep a per-release history (like
# opentelemetry-java). This is an approximation of a release-vs-release diff:
# the archived files compare the dev snapshot (which has just become <new>)
# against <old>, so any commits merged between the release and this bump are
# included too.
#
# Mirrors generate-protobuf.yml: a read-only `generate` job produces a patch
# artifact and a privileged `publish` job pushes it back.

on:
  push:
    branches:
      - "renovate/api-diff-baseline"

permissions: {}

jobs:
  generate:
    runs-on: ubuntu-24.04
    permissions:
      contents: read # checkout + read-only `git fetch origin main` for the verify step
    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
        with:
          ref: ${{ github.ref }}
          persist-credentials: false
      - uses: jdx/mise-action@1648a7812b9aeae629881980618f079932869151 # v4.0.1
        with:
          version: v2026.5.18
          sha256: cfac593469d028d7ae5fe36e37bd7c59118b5238e92d8a876209578464f24a84
      - name: Cache local Maven repository
        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
        with:
          path: ~/.m2/repository
          key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
          restore-keys: |
            ${{ runner.os }}-maven-
      - name: Archive the previous current_vs_latest
        run: |
          git fetch origin main
          baseline() {
            grep -oP '(?<=<api\.diff\.baseline\.version>)[^<]+' "$1"
          }
          OLD=$(git show origin/main:pom.xml | baseline /dev/stdin)
          NEW=$(baseline pom.xml)
          if [[ -z "$OLD" || -z "$NEW" ]]; then
            echo "::error::Could not read api.diff.baseline.version"
            exit 1
          fi
          if [[ "$OLD" == "$NEW" ]]; then
            echo "::error::api.diff.baseline.version unchanged ($NEW); nothing to bump"
            exit 1
          fi
          if [[ -d docs/apidiffs/current_vs_latest ]]; then
            cp -r docs/apidiffs/current_vs_latest "docs/apidiffs/${NEW}_vs_${OLD}"
            echo "Archived current_vs_latest as ${NEW}_vs_${OLD}"
          fi
      - name: Regenerate docs/apidiffs
        run: mise run api-diff
      - name: Validate and export docs/apidiffs as a patch
        run: |
          # Stage first so newly added files (the archived dir) are captured.
          git add docs/apidiffs
          OUTSIDE=$(git status --porcelain -- ':(exclude)docs/apidiffs')
          if [[ -n "$OUTSIDE" ]]; then
            echo "::error::Unexpected changes outside docs/apidiffs:"
            echo "$OUTSIDE"
            exit 1
          fi
          git diff --cached -- docs/apidiffs > /tmp/api-diff-baseline.patch
      - name: Upload generated patch
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        with:
          name: api-diff-baseline-patch
          path: /tmp/api-diff-baseline.patch
          retention-days: 5

  publish:
    runs-on: ubuntu-24.04
    needs: generate
    permissions:
      contents: write # push regenerated docs/apidiffs back to the renovate branch
    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
        with:
          ref: ${{ github.ref }}
          # zizmor: ignore[artipacked] -- needs credentials to push
          persist-credentials: true
      - name: Download generated patch
        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
        with:
          name: api-diff-baseline-patch
          path: /tmp/patch
      - name: Commit and push regenerated docs/apidiffs
        run: |
          PATCH=/tmp/patch/api-diff-baseline.patch
          if [[ ! -s "$PATCH" ]]; then
            echo "No regenerated changes to commit"
            exit 0
          fi
          git apply "$PATCH"
          # Note: GITHUB_TOKEN pushes don't trigger CI re-runs.
          # Close and reopen the PR to trigger CI after this commit.
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git add docs/apidiffs
          git commit -m "chore: regenerate docs/apidiffs"
          git push