feat(ci): add image signing with cosign (#175)

.github/workflows/build.yaml

@@ -27,20 +27,32 @@ concurrency:
 jobs:
   build-and-push-image:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+      # This is used to complete the identity challenge
+      # with sigstore/fulcio when running outside of PRs.
+      id-token: write
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
       - name: Initialize Docker Buildx
         uses: docker/setup-buildx-action@v2.0.0
         with:
           install: true
+      - name: Inject slug/short variables
+        uses: rlespinasse/github-slug-action@v4.4.1
+      - name: Install cosign
+        if: github.event_name != 'pull_request'
+        uses: sigstore/cosign-installer@f3c664df7af409cb4873aa5068053ba9d61a57b6 #v2.6.0
+        with:
+          cosign-release: 'v1.13.1'
       - name: Tailscale
         uses: tailscale/github-action@v1
         with:
           authkey: ${{ secrets.TAILSCALE_AUTHKEY }}
-      - name: Checkout repository
-        uses: actions/checkout@v3
-      - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4.4.1
       - name: Login to GitHub Container Registry
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v2
         with:
           registry: ghcr.io
@@ -53,6 +65,7 @@ jobs:
           password: ${{ secrets.TAILSCALE_DOCKER_PASSWORD }}
           registry: registry.internal.huggingface.tech
       - name: Login to Azure Container Registry
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v2.1.0
         with:
           username: ${{ secrets.AZURE_DOCKER_USERNAME }}
@@ -74,7 +87,7 @@ jobs:
             type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', github.event.repository.default_branch) }}
             type=raw,value=sha-${{ env.GITHUB_SHA_SHORT }}
       - name: Build and push Docker image
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v4
         with:
           context: .
           file: Dockerfile
@@ -85,23 +98,34 @@ jobs:
           cache-from: type=registry,ref=registry.internal.huggingface.tech/api-inference/community/text-generation-inference:cache,mode=max
           cache-to: type=registry,ref=registry.internal.huggingface.tech/api-inference/community/text-generation-inference:cache,mode=max
 
+      # 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.
+      - name: Sign the published Docker image
+        if: ${{ github.event_name != 'pull_request' }}
+        env:
+          COSIGN_EXPERIMENTAL: "true"
+        # This step uses the identity token to provision an ephemeral certificate
+        # against the sigstore community Fulcio instance.
+        run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign {}@${{ steps.build-and-push.outputs.digest }}
+
   build-and-push-sagemaker-image:
     needs:
       - build-and-push-image
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
       - name: Initialize Docker Buildx
         uses: docker/setup-buildx-action@v2.0.0
         with:
           install: true
+      - name: Inject slug/short variables
+        uses: rlespinasse/github-slug-action@v4.4.1
       - name: Tailscale
         uses: tailscale/github-action@v1
         with:
           authkey: ${{ secrets.TAILSCALE_AUTHKEY }}
-      - name: Checkout repository
-        uses: actions/checkout@v3
-      - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4.4.1
       - name: Login to internal Container Registry
         uses: docker/login-action@v2.1.0
         with: