Rework release workflow (#1609)

Change the release workflow and jobs to ensure more of it is always
exercised for any change and only the actual publishing of the release
is the only part that is limited to be run when tagged.

Additionally try to enable caching and save the generated notes as an
artifact in case the final step fails.

.github/workflows/release.yml

@@ -2,13 +2,17 @@ name: release
 
 on:
   push:
+    branches:
+      - '**'
     tags:
       - '*.*.*'
 
 jobs:
-  release:
-    name: Create Release
+  release-notes:
+    name: Generate Release Notes
     runs-on: ubuntu-latest
+    outputs:
+      release_branch: ${{ steps.prep.outputs.release_branch }}
     steps:
       -
         name: Checkout code
@@ -23,7 +27,7 @@ jobs:
           github-token: ${{secrets.GITHUB_TOKEN}}
           result-encoding: string
           script: |
-            repo = await github.repos.get({
+            repo = await github.rest.repos.get({
                 owner: context.repo.owner,
                 repo: context.repo.repo,
             })
@@ -34,16 +38,24 @@ jobs:
         run: |
           set -eu -o pipefail
 
-          # exclude unreleased in case re-running workflow
-          echo "unreleased=false" >> .github_changelog_generator
           echo "max-issues=200" >> .github_changelog_generator
-          # in case we've tagged subsequently ensure consistent run
-          NEXT_TAG_SHA1="$(git rev-list --tags --skip=0 --no-walk | grep -B 1 ${{ github.sha }} || true)"
-          if [[ "${NEXT_TAG_SHA1:-}" != "${{ github.sha }}" ]]
+          # cache requests to reduce load on API
+          echo "cache-file=.github_changelog_generator_cache" >> .github_changelog_generator
+
+          # only apply this section if triggered by a tag event
+          if [[ ${GITHUB_REF} == refs/tags/* ]]
           then
-              NEXT_TAG=$(git describe --tags --abbrev=0 ${NEXT_TAG_SHA1})
-              echo "due-tag=${NEXT_TAG}" >> .github_changelog_generator
+            # exclude unreleased in case re-running workflow
+              echo "unreleased=false" >> .github_changelog_generator
+              # in case we've tagged subsequently ensure consistent run
+              NEXT_TAG_SHA1="$(git rev-list --tags --skip=0 --no-walk | grep -B 1 ${{ github.sha }} || true)"
+              if [[ "${NEXT_TAG_SHA1:-}" != "${{ github.sha }}" ]]
+              then
+                  NEXT_TAG=$(git describe --tags --abbrev=0 ${NEXT_TAG_SHA1})
+                  echo "due-tag=${NEXT_TAG}" >> .github_changelog_generator
+              fi
           fi
+
           # limit list to next tag if any
           LAST_TAG=$(git describe --tags --abbrev=0 HEAD~1 2>/dev/null || true)
 
@@ -78,6 +90,22 @@ jobs:
           token: ${{ secrets.GITHUB_TOKEN }}
           since_tag: ${{ steps.prep.outputs.previous_version }}
           output: release_notes.md
+      -
+        uses: actions/upload-artifact@v2
+        with:
+          name: release-notes
+          path: release_notes.md
+
+  publish-release:
+    name: Create Release
+    needs: release-notes
+    if: startsWith(github.ref, 'refs/tags/')
+    runs-on: ubuntu-latest
+    steps:
+      -
+        uses: actions/download-artifact@v2
+        with:
+          name: release-notes
       -
         name: Create Release
         id: create_release
@@ -86,6 +114,6 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           tag_name: ${{ github.ref }}
-          commitish: ${{ steps.prep.outputs.release_branch }}
+          commitish: ${{ needs.release-notes.outputs.release_branch }}
           release_name: Release ${{ github.ref }}
           body_path: release_notes.md