Build and deploy docker image on master commit or tag

Automate docker image deployment to dockerhub using repository triggers

.github/workflows/dockerhub.yml

@@ -0,0 +1,48 @@
+name: Publish Docker image to Dockerhub
+
+on:
+  push:
+    branches:
+      - 'master'
+    tags:
+      - '*.*.*'
+    # don't trigger if just updating docs
+    paths-ignore:
+      - '**.md'
+
+jobs:
+  push_to_registry:
+    name: Push Docker image to Docker Hub
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+      
+      - name: Log in to Docker Hub
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: krateng/maloja
+          # generate Docker tags based on the following events/attributes
+          tags: |
+            type=raw,value=latest,enable=${{ endsWith(github.ref, 'master') }}
+            type=ref,event=branch,enable=${{ !endsWith(github.ref, 'master') }}
+            type=semver,pattern={{version}}
+          flavor: |
+            latest=false
+      
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+