ci: use gha cache and fix release-please triggers (#966)

This pull request updates the Docker build and caching strategy in the
CI and release GitHub Actions workflows. The main improvements are
switching to GitHub Actions (GHA) cache storage for Docker layers,
simplifying the build and test steps, and ensuring certain jobs are
skipped for release-please branches.

**CI Workflow improvements:**

* Switched Docker image caching from manual artifact upload/download to
using `docker/build-push-action` with GHA cache storage, streamlining
the build and test process (`.github/workflows/ci.yml`).
[[1]](diffhunk://#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fR129-R146)
[[2]](diffhunk://#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fL161-R168)
* Added job conditions to skip Docker build and test steps for
release-please branches in pull requests, reducing unnecessary CI runs
(`.github/workflows/ci.yml`).
[[1]](diffhunk://#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fR129-R146)
[[2]](diffhunk://#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03fL161-R168)

**Release Workflow improvements:**

* Removed local Docker cache management and replaced with GHA cache for
Docker buildx, simplifying cache handling and improving cache sharing
across runners (`.github/workflows/release.yml`).
[[1]](diffhunk://#diff-87db21a973eed4fef5f32b267aa60fcee5cbdf03c67fafdc2a9b553bb0b15f34L157-L164)
[[2]](diffhunk://#diff-87db21a973eed4fef5f32b267aa60fcee5cbdf03c67fafdc2a9b553bb0b15f34L177-R170)
[[3]](diffhunk://#diff-87db21a973eed4fef5f32b267aa60fcee5cbdf03c67fafdc2a9b553bb0b15f34L191-L195)

These changes make the workflows more efficient, easier to maintain, and
better leverage GitHub Actions built-in caching for Docker images.

Author: gildesmarais

.github/workflows/ci.yml

@@ -126,26 +126,24 @@ jobs:
       - ruby
       - openapi
       - frontend
+    if: github.event_name != 'pull_request' || !startsWith(github.head_ref, 'release-please--')
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
-
+      - uses: docker/setup-buildx-action@v4
       - name: Build Docker smoke image
-        run: docker build -t html2rss/web -f Dockerfile .
-
-      - name: Export Docker smoke image
-        run: docker save html2rss/web -o /tmp/html2rss-web-smoke-image.tar
-
-      - name: Upload Docker smoke image
-        uses: actions/upload-artifact@v7
+        uses: docker/build-push-action@v7
         with:
-          name: docker-smoke-image
-          path: /tmp/html2rss-web-smoke-image.tar
-          retention-days: 1
+          context: .
+          load: true
+          tags: html2rss/web
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
   docker-test:
     needs:
       - docker-build-smoke-image
+    if: github.event_name != 'pull_request' || !startsWith(github.head_ref, 'release-please--')
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -158,14 +156,15 @@ jobs:
         with:
           bundler-cache: true
 
-      - name: Download Docker smoke image
-        uses: actions/download-artifact@v8
-        with:
-          name: docker-smoke-image
-          path: /tmp
+      - uses: docker/setup-buildx-action@v4
 
-      - name: Load Docker smoke image
-        run: docker load -i /tmp/html2rss-web-smoke-image.tar
+      - name: Load Docker smoke image from cache
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          load: true
+          tags: html2rss/web
+          cache-from: type=gha
 
       - name: Run Docker smoke test
         env:

.github/workflows/release.yml

@@ -154,14 +154,6 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
-      - name: Cache Docker layers
-        uses: actions/cache@v4
-        with:
-          path: /tmp/.buildx-cache
-          key: ${{ runner.os }}-buildx-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-buildx-
-
       - name: Build and push Docker image
         uses: docker/build-push-action@v7
         env:
@@ -174,8 +166,8 @@ jobs:
             BUILD_TAG=${{ env.RELEASE_VERSION }}
             GIT_SHA=${{ needs.guard.outputs.target_sha }}
           platforms: linux/amd64,linux/arm64
-          cache-from: type=local,src=/tmp/.buildx-cache
-          cache-to: type=local,dest=/tmp/.buildx-cache-new
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
           provenance: true
           sbom: true
           labels: |
@@ -188,11 +180,6 @@ jobs:
             org.opencontainers.image.url=https://github.com/${{ github.repository }}/releases/tag/${{ env.RELEASE_TAG }}
             org.opencontainers.image.version=${{ env.RELEASE_VERSION }}
 
-      - name: Move updated cache into place
-        run: |
-          rm -rf /tmp/.buildx-cache
-          mv /tmp/.buildx-cache-new /tmp/.buildx-cache
-
       - name: Summarize published image tags
         run: |
           {