Add github action

.github/workflows/ci.yml

@@ -0,0 +1,57 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - 'master'
+      - 'upgrade'
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Prepare
+        id: prep
+        run: |
+          DOCKER_IMAGE=ghcr.io/poniverse/pony.fm
+          VERSION=edge
+          if [[ $GITHUB_REF == refs/tags/* ]]; then
+            VERSION=${GITHUB_REF#refs/tags/}
+          elif [[ $GITHUB_REF == refs/heads/* ]]; then
+            VERSION=$(echo ${GITHUB_REF#refs/heads/} | sed -r 's#/+#-#g')
+          elif [[ $GITHUB_REF == refs/pull/* ]]; then
+            VERSION=pr-${{ github.event.number }}
+          fi
+          TAGS="${DOCKER_IMAGE}:${VERSION}"
+          if [ "${{ github.event_name }}" = "push" ]; then
+            TAGS="$TAGS,${DOCKER_IMAGE}:sha-${GITHUB_SHA::8}"
+          fi
+          echo ::set-output name=version::${VERSION}
+          echo ::set-output name=tags::${TAGS}
+          echo ::set-output name=created::$(date -u +'%Y-%m-%dT%H:%M:%SZ')
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.CR_PAT }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.prep.outputs.tags }}
+          cache-from: type=registry,ref=ghcr.io/poniverse/pony.fm:master
+          cache-to: type=inline
+          labels: |
+            org.opencontainers.image.source=${{ github.event.repository.html_url }}
+            org.opencontainers.image.created=${{ steps.prep.outputs.created }}
+            org.opencontainers.image.revision=${{ github.sha }}