[skip ci] Build & push to DockerHub w/ GH Actions

.github/workflows/dockerhub.yml

@@ -0,0 +1,59 @@
+name: DockerHub
+
+on:
+  push:
+    branches:
+      - master
+      - dev
+      - stable
+    tags:
+      - 'v*.*.*'
+
+jobs:
+  multiarch-build:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+        
+      - name: Get Docker tags
+        id: docker_meta
+        uses: crazy-max/ghaction-docker-meta@v1
+        with:
+          images: jrcs/letsencrypt-nginx-proxy-companion
+          tag-semver: |
+            {{version}}
+            {{major}}.{{minor}}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      
+      - name: Login to DockerHub
+        uses: docker/login-action@v1 
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      
+      - name: Retrieve version
+        run: echo "GIT_DESCRIBE=$(git describe --tags)" >> $GITHUB_ENV
+      
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          build-args: GIT_DESCRIBE=${{ env.GIT_DESCRIBE }} 
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          push: true
+          tags: |
+            ${{ github.ref != 'refs/heads/master' && steps.docker_meta.outputs.tags || '' }}
+            ${{ github.ref == 'refs/heads/master' && 'jrcs/letsencrypt-nginx-proxy-companion:latest' || '' }}
+          labels: ${{ steps.docker_meta.outputs.labels }}
+
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}