redo github workflow for docker image

.github/workflows/docker-image.yml

@@ -1,22 +1,33 @@
-name: Docker Image CI
+name: Publish Docker image
 
 on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
+  release:
+    types: [published]
 
 jobs:
-
-  build:
-
+  push_to_registry:
+    name: Push Docker image to Docker Hub
     runs-on: ubuntu-latest
-
     steps:
-    - uses: actions/checkout@v2
-    - name: Login to Docker
-      run: docker login --username ${{ secrets.DOCKER_USER }} --password ${{ secrets.DOCKER_TOKEN }}
-    - name: Build the Docker image
-      run: docker build . --file Dockerfile --tag tteoh/kasm-qgis:$(date +%s)
-    - name: Publish Docker image
-      run: docker push tteoh/kasm-qgis:$(date +%s)
+      - name: Check out the repo
+        uses: actions/checkout@v2
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
+        with:
+          username: ${{ secrets.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
+        with:
+          images: tteoh/kasm-qgis
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}