Add GitHub Actions workflow to build Docker image (#81)

.github/workflows/main.yml

@@ -0,0 +1,48 @@
+name: Main
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push-docker-image:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Log into registry ${{ env.REGISTRY }}
+        uses: docker/login-action@v1
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Setup Docker buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v2
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+      - name: Build and Push Versioned Docker Image
+        id: build-and-push
+        uses: docker/build-push-action@v2
+        if: ${{ github.ref != 'refs/heads/main' }}
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+      - name: Build and Push Latest Docker Image
+        id: build-and-push-latest
+        uses: docker/build-push-action@v2
+        if: ${{ github.ref == 'refs/heads/main' }}
+        with:
+          context: .
+          push: true
+          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+          labels: ${{ steps.meta.outputs.labels }}