add Docker build multi-arch (#196)

Author: armandleopold

.github/workflows/docker-builds.yml

@@ -0,0 +1,75 @@
+name: docker-build-push
+
+on:
+  push:
+    branches:
+      - 'main'
+    tags:
+      - '*'
+
+  pull_request:
+    branches:
+      - 'main'
+
+  workflow_dispatch:
+
+env:
+  IMAGE_NAME: "gitlab-monitor"
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Prepare
+        id: prep
+        run: |
+          BASE_DIR=.
+          IMAGE_ID=ghcr.io/${{ github.repository_owner }}/$IMAGE_NAME
+
+          # Change all uppercase to lowercase
+          IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')
+
+          # Strip git ref prefix from version
+          VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')
+
+          # Strip "v" prefix from tag name
+          [[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION | sed -e 's/^v//')
+
+          # Use Docker `latest` tag convention
+          [ "$VERSION" == "main" ] && VERSION=latest
+
+          VERSION=$VERSION
+          IMAGE_ID=$IMAGE_ID
+          echo ::set-output name=version::${VERSION}
+          echo ::set-output name=image_id::${IMAGE_ID}
+          echo ::set-output name=base_dir::${BASE_DIR}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        with:
+          platforms: all
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+        with:
+          install: true
+          version: latest
+
+      - name: Log into registry
+        run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin
+
+      - name: Build and Push
+        uses: docker/build-push-action@v2
+        with:
+          build-args: VERSION=${{ steps.prep.outputs.version }}
+          context: ${{ steps.prep.outputs.base_dir }}/
+          file: ${{ steps.prep.outputs.base_dir }}/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ${{ steps.prep.outputs.image_id }}:${{ steps.prep.outputs.version }}