Automate post-release step (#12463)

Author: trask

.github/workflows/release.yml

@@ -21,6 +21,7 @@ jobs:
       - required-jobs
     outputs:
       version: ${{ steps.create-github-release.outputs.version }}
+      prior-version: ${{ steps.create-github-release.outputs.prior-version }}
     steps:
       - run: |
           if [[ $GITHUB_REF_NAME != release/* ]]; then
@@ -177,6 +178,7 @@ jobs:
                             opentelemetry-java-instrumentation-SBOM.zip
 
           echo "version=$VERSION" >> $GITHUB_OUTPUT
+          echo "prior-version=$PRIOR_VERSION" >> $GITHUB_OUTPUT
 
   merge-change-log-to-main:
     runs-on: ubuntu-latest
@@ -233,3 +235,53 @@ jobs:
           gh pr create --title "$message" \
                        --body "$body" \
                        --base main
+
+  update-apidiff-baseline-to-released-version:
+    runs-on: ubuntu-latest
+    needs:
+      - release
+    steps:
+      - uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4.2.1
+        with:
+          ref: main
+
+      - name: Use CLA approved github bot
+        run: .github/scripts/use-cla-approved-github-bot.sh
+
+      - name: Wait for release to be available in maven central
+        run: |
+          until curl --silent \
+                     --show-error \
+                     --output /dev/null \
+                     --head \
+                     --fail \
+                     https://repo1.maven.org/maven2/io/opentelemetry/javaagent/opentelemetry-javaagent/$VERSION/opentelemetry-javaagent-$VERSION.jar
+          do
+            sleep 60
+          done
+
+      - name: Update apidiff baseline
+        env:
+          VERSION: ${{ needs.release.outputs.version }}
+          PRIOR_VERSION: ${{ needs.release.outputs.prior-version }}
+        run: |
+          ./gradlew japicmp -PapiBaseVersion=$PRIOR_VERSION -PapiNewVersion=$VERSION
+          ./gradlew --refresh-dependencies japicmp
+
+      - name: Create pull request against main
+        env:
+          VERSION: ${{ needs.release.outputs.version }}
+          # not using secrets.GITHUB_TOKEN since pull requests from that token do not run workflows
+          GH_TOKEN: ${{ secrets.OPENTELEMETRYBOT_GITHUB_TOKEN }}
+        run: |
+          message="Update apidiff baseline to released version $VERSION"
+          body="Update apidiff baseline to released version \`$version\`."
+          branch="opentelemetrybot/update-apidiff-baseline-to-released-version-${VERSION}"
+
+          git checkout -b $branch
+          git add docs/apidiffs
+          git commit -m "$message"
+          git push --set-upstream origin $branch
+          gh pr create --title "$message" \
+                       --body "$body" \
+                       --base main

RELEASING.md

@@ -65,24 +65,13 @@ and deadlocks.
     e.g. `release/v1.9.x`, and click the "Run workflow" button below that.
   - This workflow will publish the artifacts to maven central and will publish a GitHub release
     with release notes based on the change log and with the javaagent jar attached.
+  - Review and merge the pull request that it creates for updating the apidiff baseline version
+    to the newly released version (note that this pull request won't be made until after the release
+    is available in maven central).
   - Review and merge the pull request that it creates for updating the change log in main
     (note that if this is not a patch release then the change log on main may already be up-to-date,
     in which case no pull request will be created).
 
-## Update release versions in documentations
-
-After releasing is done, you need to first update the docs. This needs to happen after artifacts have propagated
-to Maven Central so should probably be done an hour or two after the release workflow finishes.
-
-```sh
-./gradlew japicmp -PapiBaseVersion=a.b.c -PapiNewVersion=x.y.z
-./gradlew --refresh-dependencies japicmp
-```
-
-Where `x.y.z` is the version just released and `a.b.c` is the previous version.
-
-Create a PR to mark the new release in docs on the main branch.
-
 ## Credentials
 
 Same as the core repo, see [opentelemetry-java/RELEASING.md#credentials](https://github.com/open-telemetry/opentelemetry-java/blob/main/RELEASING.md#credentials).