Add docker build/push action

.github/workflows/docker-push.yml

@@ -0,0 +1,44 @@
+name: Docker Build/Publish Image
+on:
+  push:    
+    branches: [ main ]
+jobs:   
+  build:    
+    runs-on: ubuntu-18.04    
+    env:      
+      DOCKER_REGISTRY: hub.docker.io   
+      DOCKER_IMAGE: RyanConnell/concert-watch      
+      DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
+      DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}  
+      DOCKER_TARGET_PLATFORM: linux/arm/v7
+
+    steps:    
+    - name: Checkout the code       
+      uses: actions/checkout@v1
+
+    - name: Set up Docker Buildx      
+      uses: crazy-max/ghaction-docker-buildx@v1      
+      with:        
+        version: latest
+
+    - name: Prepare      
+      if: success()      
+      id: prepare      
+      run: |        
+        echo ::set-output name=docker_platform::${DOCKER_TARGET_PLATFORM}        
+        echo ::set-output name=docker_image::${DOCKER_REGISTRY}/${DOCKER_IMAGE}        
+        echo ::set-output name=version::${GITHUB_RUN_NUMBER}
+        
+    - name: Docker Login      
+      if: success()      
+      run: |        
+        echo "${DOCKER_PASSWORD}" | docker login ${DOCKER_REGISTRY} --username "${DOCKER_USERNAME}" --password-stdin
+        
+    - name: Run Buildx (push image)      
+      if: success()      
+      run: |        
+        docker buildx build \
+        --platform ${{ steps.prepare.outputs.docker_platform }} \
+        --tag ${{ steps.prepare.outputs.docker_image }}:${{ steps.prepare.outputs.version }} \
+        --file ./Dockerfile \
+        --output type=image,push=true .