Add docker workflow

.github/workflows/docker-ubuntu-image.yml

@@ -0,0 +1,44 @@
+name: Build Docker Ubuntu Image
+
+on:
+  push:
+    branches:
+      - 'master'
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
+
+      -
+        name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      -
+        name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      -
+        name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          context: ./docker
+          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+