Add SLSA generator (#35)

.github/workflows/release.yaml

@@ -8,29 +8,69 @@ on:
 jobs:
   release-container-images:
     name: build and push to ghcr.io
+    strategy:
+      matrix:
+        component:
+        - informer
+        - webhook
     runs-on: ubuntu-22.04
     permissions:
       packages: write
 
+    outputs:
+      informer_image: ${{ steps.release.outputs.informer_image }}
+      informer_digest: ${{ steps.release.outputs.informer_digest }}
+      webhook_image: ${{ steps.release.outputs.webhook_image }}
+      webhook_digest: ${{ steps.release.outputs.webhook_digest }}
+
     steps:
     - uses: actions/setup-go@v4
       with:
         go-version: 1.21.x
     - uses: ko-build/[email protected]
     - uses: actions/checkout@v4
 
-    - name: Build and push
+    - id: release
+      name: Build and push
       env:
         KO_DOCKER_REPO: ghcr.io/norbjd/k8s-pod-cpu-booster
       run: |
         # something like 202403241909-abcdef01 if we want to use a specific version
         UNIQUE_TAG="$(TZ=UTC0 git log -1 --format=%cd --date=format-local:%Y%m%d%H%M)-$(git rev-parse --short HEAD)"
 
-        ko build ./cmd/informer ./cmd/webhook \
+        ko build ./cmd/${{ matrix.component }} \
           --base-import-paths \
           --sbom=none \
+          --image-refs=.digest \
           --tags=$GITHUB_REF_NAME,$UNIQUE_TAG
 
+        image=$(cat .digest | cut -d'@' -f1 | cut -d':' -f1)
+        digest=$(cat .digest| cut -d'@' -f2)
+        echo "${{ matrix.component }}_image=$image" >> "$GITHUB_OUTPUT"
+        echo "${{ matrix.component }}_digest=$digest" >> "$GITHUB_OUTPUT"
+  
+  # see https://github.com/slsa-framework/slsa-github-generator/blob/v1.10.0/internal/builders/container/README.md#ko
+  provenance:
+    needs:
+      - release-container-images
+    strategy:
+      matrix:
+        component:
+        - informer
+        - webhook
+    permissions:
+      actions: read
+      id-token: write
+      packages: write
+    uses: slsa-framework/slsa-github-generator/.github/workflows/[email protected]
+    with:
+      image: "${{ needs.release-container-images.outputs[format('{0}_image', matrix.component)] }}"
+      digest: "${{ needs.release-container-images.outputs[format('{0}_digest', matrix.component)] }}"
+      registry-username: ${{ github.actor }}
+      compile-generator: true
+    secrets:
+      registry-password: ${{ secrets.GITHUB_TOKEN }}
+
   release-helm-chart:
     name: release helm chart
     runs-on: ubuntu-latest