Add workflow to publish Docker image to dockerhub

.github/workflows/docker-image-publish.yml

@@ -0,0 +1,44 @@
+name: Publish Docker image
+on:
+  push:
+    branches:
+      - "master"
+    tags:
+      - "v*"
+  pull_request:
+    branches:
+      - "master"
+jobs:
+  push_to_registry:
+    name: Push Docker image to Docker Hub
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Docker meta
+        id: meta
+        uses: crazy-max/ghaction-docker-meta@v2
+        with:
+          images: hibiken/asynqmon
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}

Dockerfile

@@ -36,7 +36,7 @@ RUN go mod download
 COPY . .
 
 # Copy frontend static files from /static to the root folder of the backend container.
-COPY --from=frontend ["/static/build", "/ui/build"]
+COPY --from=frontend ["/static/build", "ui/build"]
 
 # Set necessary environmet variables needed for the image and build the server.
 ENV CGO_ENABLED=0 GOOS=linux GOARCH=amd64