Automatically dispatch emscripten release tag action (#1442)

This PR add several features to release automation:

1. The existing tag-release job has an output that indicates whether the
triggering commit
    is a release (i.e. whether it matches the regex)
2. The new followup job runs a new script which fetches the recent
emscripten-releases
revisions, reads the DEPS file from the 'latest' release in
emscripten-releases-tags.json
to find the corresponding emscripten revision and writes it into the
environment
2. The final step reads the emscripten revision from the environment and
creates a
workflow_dispatch event to run the tag-release.yml job on the emscripten
repo

.github/workflows/create-release.yml

@@ -23,5 +23,10 @@ jobs:
         uses: peter-evans/create-pull-request@v6
         with:
           title: Release ${{ env.RELEASE_VERSION }}
-          commit-message: Release ${{ env.RELEASE_VERSION }}
+          commit-message: |
+            Release ${{ env.RELEASE_VERSION }}
+          body: |
+            With emscripten-releases revisions:
+              https://chromium.googlesource.com/emscripten-releases/+/${{ inputs.lto-sha }} (LTO)
+              https://chromium.googlesource.com/emscripten-releases/+/${{ inputs.nonlto-sha }} (asserts)
           delete-branch: true

.github/workflows/tag-release.yml

@@ -4,33 +4,74 @@ name: Create release tag
 
 on:
   push:
-    paths: [ emscripten-releases-tags.json, .github/workflows/tag-release.yml ]
+    paths:
+      - emscripten-releases-tags.json
+      - .github/workflows/tag-release.yml
+    branches:
+      - main
   workflow_dispatch:
 
 jobs:
-    tag-release:
-      # Only activate for commits created by the create-release.yml workflow.
-      # The assumption is that when manual changes happen, we want to handle
-      # tagging manually too.
-      if: github.event.head_commit.author.username == 'github-actions[bot]'
-      runs-on: ubuntu-latest
-      steps:
-        - name: Match message and create tag
-          uses: actions/github-script@v7
-          with:
-            script: |
-              const message = `${{ github.event.head_commit.message }}`
-              const regex = /Release ([0-9]+.[0-9]+.[0-9]+)/
-              const match = message.match(regex)
-              if (match) {
-                const release = match[1]
-                console.log(`Matched release ${release}`)
-                await github.rest.git.createRef({
-                  owner: context.repo.owner,
-                  repo: context.repo.repo,
-                  ref: `refs/tags/${release}`,
-                  sha: context.sha
-                })
-              } else {
-                console.log(`Commit message: ${message} did not match pattern`)
-              }
+  tag-release:
+    # Only activate for commits created by the create-release.yml workflow.
+    # The assumption is that when manual changes happen, we want to handle
+    # tagging manually too.
+    name: Check for release commit and create tag
+    if: github.event.head_commit.author.username == 'github-actions[bot]'
+    runs-on: ubuntu-latest
+    outputs:
+      is_release: ${{ steps.create-tag.outputs.result }}
+    steps:
+      - name: Match message and create tag
+        id: create-tag
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.TEST_TOKEN }}
+          # A commit with the message of the form 'Release X.Y.Z' is expected
+          # to have been created by create_release.py and update the latest
+          # release in emscripten-releases-tags.json
+          script: |
+            const message = `${{ github.event.head_commit.message }}`
+            const regex = /Release ([0-9]+.[0-9]+.[0-9]+)/;
+            const match = message.match(regex);
+            let is_release = false;
+            if (match) {
+              const release = match[1];
+              console.log(`Matched release ${release}`);
+              await github.rest.git.createRef({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                ref: `refs/tags/${release}`,
+                sha: context.sha
+              });
+              is_release = true;
+            } else {
+              console.log(`Commit message: '${message}' did not match pattern`);
+            }
+            return is_release;
+
+  dispatch-emscripten-tag:
+    name: Dispatch workflow to tag emscripten repo
+    runs-on: ubuntu-latest
+    needs: tag-release
+    if: ${{ needs.tag-release.outputs.is_release == 'true' }}
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+      - name: Find emscripten revision
+        # get_emscripten_revision_info.py sets env.EMSCRIPTEN_HASH to the
+        # emscripten hash associated with the latest release in
+        # emscripten-releases-tags.json
+        run: python3 scripts/get_emscripten_revision_info.py
+      - name: Dispatch emscripten workflow
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.TEST_TOKEN }}
+          script: |
+            await github.rest.actions.createWorkflowDispatch({
+              owner: context.repo.owner,
+              repo: 'emscripten',
+              workflow_id: 'tag-release.yml',
+              ref: 'main',
+              inputs: { 'release-sha': '${{ env.EMSCRIPTEN_HASH }}' }
+            });