Add auto-deploys, optimise Dockerfile & add running SHA to RIGS

.github/workflows/ci.yml

@@ -77,18 +77,25 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
-  docker:
-    name: Docker image
-    runs-on: ubuntu-latest
+  # Each architecture builds on a native runner: emulating arm64 under QEMU (compiling pycairo, npm, uv) was the slow part
+  docker-build:
+    name: Docker build (${{ matrix.platform }})
+    runs-on: ${{ matrix.runner }}
     needs: [lint, test]
     permissions:
       contents: read
       packages: write
+    strategy:
+      fail-fast: true
+      matrix:
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-latest
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
     steps:
       - uses: actions/checkout@v4
 
-      - uses: docker/setup-qemu-action@v3
-
       - uses: docker/setup-buildx-action@v3
 
       # Only authenticate when we are actually going to push (never for PRs, which may come from forks)
@@ -100,6 +107,60 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - id: build
+        name: Build (and push by digest on master)
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: ${{ matrix.platform }}
+          build-args: GIT_SHA=${{ github.sha }}
+          outputs: type=image,name=ghcr.io/${{ github.repository }},push-by-digest=true,name-canonical=true,push=${{ github.event_name == 'push' }}
+          cache-from: type=gha,scope=${{ matrix.platform }}
+          cache-to: type=gha,mode=max,scope=${{ matrix.platform }}
+
+      - name: Export digest
+        if: github.event_name == 'push'
+        env:
+          DIGEST: ${{ steps.build.outputs.digest }}
+        run: |
+          mkdir -p "$RUNNER_TEMP/digests"
+          touch "$RUNNER_TEMP/digests/${DIGEST#sha256:}"
+
+      - name: Upload digest
+        if: github.event_name == 'push'
+        uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ strategy.job-index }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  docker:
+    name: Docker image
+    runs-on: ubuntu-latest
+    needs: [docker-build]
+    if: github.event_name == 'push'
+    outputs:
+      tag: ${{ steps.sha-tag.outputs.tag }}
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          path: ${{ runner.temp }}/digests
+          pattern: digests-*
+          merge-multiple: true
+
+      - uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - id: meta
         uses: docker/metadata-action@v5
         with:
@@ -108,13 +169,40 @@ jobs:
             type=raw,value=latest
             type=sha
 
-      - name: Build (and push on master)
-        uses: docker/build-push-action@v6
-        with:
-          context: .
-          platforms: linux/amd64,linux/arm64
-          push: ${{ github.event_name == 'push' }}
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
+      - id: sha-tag
+        name: Pick the commit tag
+        env:
+          TAGS: ${{ steps.meta.outputs.tags }}
+        run: |
+          ref="$(grep -m1 ':sha-' <<< "$TAGS")"
+          test -n "$ref"
+          echo "tag=${ref##*:}" >> "$GITHUB_OUTPUT"
+
+      - name: Create multi-arch manifest
+        working-directory: ${{ runner.temp }}/digests
+        env:
+          IMAGE: ghcr.io/${{ github.repository }}
+        run: |
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $(printf "$IMAGE@sha256:%s " *)
+
+  deploy:
+    name: Deploy
+    runs-on: ubuntu-latest
+    needs: [docker]
+    if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+    environment: production
+    concurrency: deploy-production
+    steps:
+      - name: Deploy the image built for this commit
+        env:
+          DEPLOY_SSH_KEY: ${{ secrets.DEPLOY_SSH_KEY }}
+          DEPLOY_KNOWN_HOSTS: ${{ secrets.DEPLOY_KNOWN_HOSTS }}
+          TAG: ${{ needs.docker.outputs.tag }}
+        run: |
+          install -m 700 -d ~/.ssh
+          printf '%s\n' "$DEPLOY_SSH_KEY" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          printf '%s\n' "$DEPLOY_KNOWN_HOSTS" > ~/.ssh/known_hosts
+          ssh deploy@rigs.nottinghamtec.co.uk "$TAG"