Create and publish a Docker image to ghcr

.github/workflows/publish-ghcr.yml

@@ -1,35 +1,60 @@
-name: Build and Push Docker Image
+#
+name: Create and publish a Docker image to ghcr
 
 on:
   workflow_run:
     workflows: ["Run Tests"] # This ensures this workflow runs after the test workflow
     types:
       - completed
 
+# Defines two custom environment variables for the workflow. These are used for the Container registry domain, and a name for the Docker image that this workflow builds.
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+# There is a single job in this workflow. It's configured to run on the latest available version of Ubuntu.
 jobs:
-  build-and-push:
-    name: Build and Push Docker Image
+  build-and-push-image:
     runs-on: ubuntu-latest
-
+    # Sets the permissions granted to the `GITHUB_TOKEN` for the actions in this job.
+    permissions:
+      contents: read
+      packages: write
+      attestations: write
+      id-token: write
+      #
     steps:
-      # Checkout the repository
-      - name: Checkout code
-        uses: actions/checkout@v3
-
-      # Log in to GHCR
-      - name: Log in to GitHub Container Registry
-        uses: docker/login-action@v2
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      # Uses the `docker/login-action` action to log in to the Container registry registry using the account and password that will publish the packages. Once published, the packages are scoped to the account defined here.
+      - name: Log in to the Container registry
+        uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
         with:
-          registry: ghcr.io
-          username: ${{ secrets.GITHUB_ACTOR }}
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
+      # This step uses [docker/metadata-action](https://github.com/docker/metadata-action#about) to extract tags and labels that will be applied to the specified image. The `id` "meta" allows the output of this step to be referenced in a subsequent step. The `images` value provides the base name for the tags and labels.
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+      # This step uses the `docker/build-push-action` action to build the image, based on your repository's `Dockerfile`. If the build succeeds, it pushes the image to GitHub Packages.
+      # It uses the `context` parameter to define the build's context as the set of files located in the specified path. For more information, see "[Usage](https://github.com/docker/build-push-action#usage)" in the README of the `docker/build-push-action` repository.
+      # It uses the `tags` and `labels` parameters to tag and label the image with the output from the "meta" step.
+      - name: Build and push Docker image
+        id: push
+        uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
 
-      # Build and tag the Docker image
-      - name: Build Docker image
-        run: |
-          docker build -t ghcr.io/${{ github.repository_owner }}/${{ github.repository }}:latest .
-
-      # Push the Docker image to GHCR
-      - name: Push Docker image
-        run: |
-          docker push ghcr.io/${{ github.repository_owner }}/${{ github.repository }}:latest
+      # This step generates an artifact attestation for the image, which is an unforgeable statement about where and how it was built. It increases supply chain security for people who consume the image. For more information, see "[AUTOTITLE](/actions/security-guides/using-artifact-attestations-to-establish-provenance-for-builds)."
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@v1
+        with:
+          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}
+          subject-digest: ${{ steps.push.outputs.digest }}
+          push-to-registry: true