.github/workflows: publish docker image to ghcr.io (#4)

Author: maxenglander

.github/workflows/build.yml

@@ -0,0 +1,63 @@
+# <https://docs.github.com/en/actions/publishing-packages/publishing-docker-images>
+name: Create and publish a Docker image
+
+on:
+  push:
+    branches:
+      - main
+
+env:
+  IMAGE_NAME: ${{ github.repository }}
+  REGISTRY: ghcr.io
+
+jobs:
+  build-and-push-image:
+    permissions:
+      attestations: write
+      contents: read
+      id-token: write
+      packages: write
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - id: meta
+        name: Extract metadata (tags, labels) for Docker
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=raw,value=latest
+            type=sha
+
+      # setup qemu and buildx for cross-builds (arm64)
+      - name: Set up QEMU (for arm64 builds)
+        uses: docker/setup-qemu-action@49b3bc8e6bdd4a60e6116a5414239cba5943d3cf # v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3
+
+      - id: push
+        name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          labels: ${{ steps.meta.outputs.labels }}
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@v1
+        with:
+          push-to-registry: true
+          subject-digest: ${{ steps.push.outputs.digest }}
+          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}