From 131c85b8c7777c655dcc8bb21b9fe7883edace2a Mon Sep 17 00:00:00 2001
From: Chris Ayers <clayers@gmail.com>
Date: Wed, 14 Feb 2024 05:49:31 +0000
Subject: [PATCH] Update Docker image build workflow

---
 .github/workflows/docker-image.yml | 62 ++++++++++++++++++++++--------
 1 file changed, 45 insertions(+), 17 deletions(-)

diff --git a/.github/workflows/docker-image.yml b/.github/workflows/docker-image.yml
index ae06419..a70d1fe 100755
--- a/.github/workflows/docker-image.yml
+++ b/.github/workflows/docker-image.yml
@@ -15,43 +15,71 @@ jobs:
   build:
     runs-on: ubuntu-latest
     env:
-      REPO: 'sampleapi'
+      IMAGE_NAME: 'sampleapi'
       TAG: ${{ github.sha }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
+      # Install the cosign tool except on PR
+      # https://github.com/sigstore/cosign-installer
+      - name: Install cosign
+        if: github.event_name != 'pull_request'
+        uses: sigstore/cosign-installer@3
+        with:
+          cosign-release: 'v2.1.1'
+      # Set up BuildKit Docker container builder to be able to build
+      # multi-platform images and export cache
+      # https://github.com/docker/setup-buildx-action
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-      - name: Login to Docker 
+        uses: docker/setup-buildx-action@3
+
+      # Login against a Docker registry except on PR
+      # https://github.com/docker/login-action
+      - name: Log into registry ${{ vars.DOCKER_LOGIN_SERVER }}
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
         with:
           registry: ${{ vars.DOCKER_LOGIN_SERVER }}
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_TOKEN }}
+      # Extract metadata (tags, labels) for Docker
+      # https://github.com/docker/metadata-action
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@5
+        with:
+          images: ${{ vars.DOCKER_LOGIN_SERVER }}/${{ env.IMAGE_NAME }}
+
       - name: Build Docker Image
         uses: docker/build-push-action@v5
         with:
           context: src/SampleApi
-          load: true
-          push: false
-          tags: ${{ env.REPO }}:${{ env.TAG }}
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
       - name: Run Trivy vulnerability scanner
         uses: aquasecurity/trivy-action@master
         with:
-          image-ref: 'docker.io/library/${{ env.REPO }}:${{ env.TAG }}'
+          image-ref: 'docker.io/library/${{ env.IMAGE_NAME }}:${{ env.TAG }}'
           format: 'github'
           github-pat: ${{ github.token }}
         env:
           TRIVY_USERNAME: Username
           TRIVY_PASSWORD: Password
 
-      - name: Push image to ACR
-        uses: docker/build-push-action@v5
-        with:
-          context: src/SampleApi
-          push: true
-          tags: |
-            ${{ vars.DOCKER_LOGIN_SERVER }}/${{ env.REPO }}:latest
-            ${{ vars.DOCKER_LOGIN_SERVER }}/${{ env.REPO }}:${{ env.TAG }}
+      # Sign the resulting Docker image digest except on PRs.
+      # This will only write to the public Rekor transparency log when the Docker
+      # repository is public to avoid leaking data.  If you would like to publish
+      # transparency data even for private images, pass --force to cosign below.
+      # https://github.com/sigstore/cosign
+      - name: Sign the published Docker image
+        if: ${{ github.event_name != 'pull_request' }}
+        env:
+          # https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
+          TAGS: ${{ steps.meta.outputs.tags }}
+          DIGEST: ${{ steps.build-and-push.outputs.digest }}
+        # This step uses the identity token to provision an ephemeral certificate
+        # against the sigstore community Fulcio instance.
+        run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}