ci: add GitHub Actions workflow to build patched controller image

Author: estenrye

.github/workflows/build-controller.yaml

@@ -0,0 +1,59 @@
+name: Build patched controller image
+
+on:
+  push:
+    tags:
+      - 'v*-pf9*'
+
+jobs:
+  build:
+    name: Build and push controller image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract tag name
+        id: tag
+        run: echo "tag=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+
+      - name: Build and push
+        id: build
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: Dockerfile.controller
+          platforms: linux/amd64
+          push: true
+          tags: ghcr.io/platform9/cert-manager-controller:${{ steps.tag.outputs.tag }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Output image digest
+        run: |
+          echo "## Controller Image Built" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "**Tag:** \`${{ steps.tag.outputs.tag }}\`" >> $GITHUB_STEP_SUMMARY
+          echo "**Digest:** \`${{ steps.build.outputs.digest }}\`" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "Update pf9-flux-src kustomization.yaml with:" >> $GITHUB_STEP_SUMMARY
+          echo "\`\`\`yaml" >> $GITHUB_STEP_SUMMARY
+          echo "- name: quay.io/jetstack/cert-manager-controller" >> $GITHUB_STEP_SUMMARY
+          echo "  newName: ghcr.io/platform9/cert-manager-controller" >> $GITHUB_STEP_SUMMARY
+          echo "  newTag: ${{ steps.tag.outputs.tag }}" >> $GITHUB_STEP_SUMMARY
+          echo "  digest: ${{ steps.build.outputs.digest }}" >> $GITHUB_STEP_SUMMARY
+          echo "\`\`\`" >> $GITHUB_STEP_SUMMARY