Added Docker image + upload workflow

Author: codingPear

.github/workflows/docker-image.yml

@@ -0,0 +1,66 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+  repository_dispatch:
+    types: [alpine-update]
+  workflow_dispatch:
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest    
+    env:      
+      DOCKER_REGISTRY: ${{ secrets.DOCKER_REGISTRY }}      
+      DOCKER_IMAGE: ${{ secrets.DOCKER_IMAGE }}      
+      DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
+      DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}  
+      DOCKER_TARGET_PLATFORMS: linux/amd64,linux/arm/v7,linux/arm64
+    steps:
+    - name: Checkout the code       
+      uses: actions/checkout@v1
+    
+    # https://github.com/docker/setup-qemu-action
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v1
+    
+    # https://github.com/docker/setup-buildx-action
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1    
+      with:        
+        buildx-version: latest
+
+    - name: Prepare      
+      if: success()      
+      id: prepare      
+      run: |        
+        echo ::set-output name=docker_platform::${DOCKER_TARGET_PLATFORMS}        
+        echo ::set-output name=docker_image::${DOCKER_REGISTRY}/${DOCKER_IMAGE}        
+        echo ::set-output name=version::0.1.${GITHUB_RUN_NUMBER}
+        
+    - name: Inspect builder
+      run: |
+          echo "Name:      ${{ steps.buildx.outputs.name }}"
+          echo "Endpoint:  ${{ steps.buildx.outputs.endpoint }}"
+          echo "Status:    ${{ steps.buildx.outputs.status }}"
+          echo "Flags:     ${{ steps.buildx.outputs.flags }}"
+          echo "Platforms: ${{ steps.buildx.outputs.platforms }}"
+    
+    - name: Docker Login      
+      if: success()      
+      run: |        
+        echo "${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 }} \
+        --tag ${{ steps.prepare.outputs.docker_image }}:latest \
+        --file ./Dockerfile \
+        --output type=image,push=true .