ci: build + smoke-test the docker image, push to GHCR on tags

Author: plutoless

.github/workflows/docker.yml

@@ -0,0 +1,80 @@
+name: docker
+
+on:
+  push:
+    branches: ["**"]
+    tags: ["v*"]
+  pull_request:
+  workflow_call:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-buildx-action@v3
+
+      - id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository }}
+          tags: |
+            type=sha
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/') }}
+
+      - name: Build (load locally, no push)
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64
+          load: true
+          push: false
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Smoke test
+        run: |
+          IMAGE=$(printf '%s\n' "${{ steps.meta.outputs.tags }}" | head -n1)
+          echo "Smoke-testing $IMAGE"
+          docker run -d --name smoke -p 8000:8000 \
+            -e AGORA_APP_ID=0123456789abcdef0123456789abcdef \
+            -e AGORA_APP_CERTIFICATE=fedcba9876543210fedcba9876543210 \
+            "$IMAGE"
+          set +e
+          fail=0
+          for url in http://localhost:8000/get_config; do
+            ok=""
+            for i in $(seq 1 40); do
+              if curl -fsS "$url" -o /dev/null; then ok=1; echo "OK   $url"; break; fi
+              sleep 1
+            done
+            if [ -z "$ok" ]; then echo "FAIL $url"; fail=1; fi
+          done
+          if [ "$fail" -ne 0 ]; then docker logs smoke; fi
+          docker rm -f smoke
+          exit $fail
+
+      - name: Log in to GHCR
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Push tags
+        if: startsWith(github.ref, 'refs/tags/')
+        run: |
+          printf '%s\n' "${{ steps.meta.outputs.tags }}" | while read -r tag; do
+            [ -n "$tag" ] && docker push "$tag"
+          done