docker build/push action

.github/workflows/docker.yml

@@ -0,0 +1,64 @@
+name: Docker
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Prepare
+        id: prepare
+        run: |
+          if [[ $GITHUB_REF == refs/tags/* ]]; then
+            echo ::set-output name=version::${GITHUB_REF#refs/tags/v}
+          elif [[ $GITHUB_REF == refs/heads/master ]]; then
+            echo ::set-output name=version::latest
+          elif [[ $GITHUB_REF == refs/heads/* ]]; then
+            echo ::set-output name=version::${GITHUB_REF#refs/heads/}
+          else
+            echo ::set-output name=version::snapshot
+          fi
+          echo ::set-output name=build_date::$(date -u +'%Y-%m-%dT%H:%M:%SZ')
+          echo ::set-output name=docker_platforms::linux/amd64,linux/arm/v7
+          echo ::set-output name=docker_image::${{ secrets.DOCKER_USERNAME }}/${{ github.event.repository.name }}
+        # https://github.com/crazy-max/ghaction-docker-buildx
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: crazy-max/ghaction-docker-buildx@v1
+        with:
+          version: latest
+
+      - name: Environment
+        run: |
+          echo home=$HOME
+          echo git_ref=$GITHUB_REF
+          echo git_sha=$GITHUB_SHA
+          echo version=${{ steps.prepare.outputs.version }}
+          echo date=${{ steps.prepare.outputs.build_date }}
+          echo image=${{ steps.prepare.outputs.docker_image }}
+          echo platforms=${{ steps.prepare.outputs.docker_platforms }}
+          echo avail_platforms=${{ steps.buildx.outputs.platforms }}
+        # https://github.com/actions/checkout
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Docker Login
+        if: success()
+        env:
+          DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}
+        run: |
+          echo "${DOCKER_PASSWORD}" | docker login --username "${{ secrets.DOCKER_USERNAME }}" --password-stdin
+      - name: Docker Buildx (push)
+        if: success()
+        run: |
+          docker buildx build \
+            --platform ${{ steps.prepare.outputs.docker_platforms }} \
+            --output "type=image,push=true" \
+            --build-arg "VERSION=${{ steps.prepare.outputs.version }}" \
+            --build-arg "BUILD_DATE=${{ steps.prepare.outputs.build_date }}" \
+            --build-arg "VCS_REF=${GITHUB_SHA}" \
+            --tag "${{ steps.prepare.outputs.docker_image }}:${GITHUB_SHA}" \
+            --tag "${{ steps.prepare.outputs.docker_image }}:latest" \
+            --file Dockerfile .
+      - name: Clear
+        if: always()
+        run: |
+          rm -f ${HOME}/.docker/config.json