ci: update GitHub Actions workflow to streamline Helm chart publishing to gh-pages (#218)

This pull request updates the GitHub Actions workflow for publishing
Helm chart packages, simplifying the deployment process and improving
how the Helm repo index is managed. The workflow now directly publishes
artifacts to the `gh-pages` branch, removing the previous multi-step
deployment to GitHub Pages and associated permissions.

**Workflow and deployment simplification:**

* Removed unnecessary `pages: write` and `id-token: write` permissions
from the workflow, reflecting the new deployment approach.
* Replaced the "Build Helm repo index for Pages" step with "Build Helm
repo index for gh-pages", adding logic to fetch and merge the existing
index from the `gh-pages` branch if present. This ensures the Helm repo
index is correctly updated and avoids overwriting previous entries.

**Direct publishing to `gh-pages`:**

* Replaced the upload and deploy steps for GitHub Pages with a single
step using `peaceiris/actions-gh-pages@v4` to publish the Helm repo
directly to the `gh-pages` branch, simplifying the workflow and
eliminating the need for a separate deploy job.

Author: a-klos

.github/workflows/publish-chart-packages.yml

@@ -17,8 +17,6 @@ permissions:
   contents: write
   pull-requests: read
   packages: write
-  pages: write
-  id-token: write
 
 env:
   OCI_REGISTRY: ghcr.io
@@ -101,33 +99,30 @@ jobs:
           helm show chart "$PKG" | grep -E "^version: "
           helm push "$PKG" oci://$OCI_REGISTRY/${{ github.repository_owner }}/charts
 
-      - name: Build Helm repo index for Pages
+      - name: Build Helm repo index for gh-pages
         env:
           CHART_VERSION: ${{ steps.meta.outputs.chart_version }}
         run: |
           set -euo pipefail
           PKG=$(ls dist/*.tgz)
           REPO="${GITHUB_REPOSITORY#*/}"
           BASE_URL="https://${GITHUB_REPOSITORY_OWNER}.github.io/${REPO}"
-          helm repo index dist --url "$BASE_URL"
+          if git ls-remote --exit-code origin gh-pages >/dev/null 2>&1; then
+            git fetch origin gh-pages:gh-pages
+            if git show gh-pages:index.yaml > dist/index.yaml 2>/dev/null; then
+              helm repo index dist --url "$BASE_URL" --merge dist/index.yaml
+            else
+              helm repo index dist --url "$BASE_URL"
+            fi
+          else
+            helm repo index dist --url "$BASE_URL"
+          fi
           echo "Index generated for $BASE_URL"
 
-      - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@v3
+      - name: Publish Helm repo to gh-pages
+        uses: peaceiris/actions-gh-pages@v4
         with:
-          path: dist
-
-  deploy-pages:
-    needs: publish
-    runs-on: ubuntu-latest
-    if: ${{ needs.publish.result == 'success' }}
-    permissions:
-      pages: write
-      id-token: write
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    steps:
-      - name: Deploy to GitHub Pages
-        id: deployment
-        uses: actions/deploy-pages@v4
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_branch: gh-pages
+          publish_dir: dist
+          keep_files: true