Add GHA to publish docker image

.github/workflows/publish-docker.yml

@@ -0,0 +1,51 @@
+name: "Build and publish container image"
+
+on:
+  push:
+    branches:
+      - "main"
+      # TODO: remove. This is for testing purposes.
+      - "add-gha-for-docker-image"
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+*"
+
+jobs:
+  build-and-release-image:
+    name: "Build and release container image"
+    runs-on: "ubuntu-latest"
+    env:
+      IMAGE_NAME: "ogdc-runner"
+      # GitHub Actions expressions don't have great conditional support, so
+      # writing a ternary expression looks a lot like bash. In Python, this
+      # would read as:
+      #     github.ref_name if github.ref_type == 'tag' else 'latest'
+      #     https://docs.github.com/en/actions/learn-github-actions/expressions
+      IMAGE_TAG:
+        "${{ github.ref_type == 'tag' && github.ref_name || 'latest' }}"
+    steps:
+      - name: "Check out repository"
+        uses: "actions/checkout@v3"
+
+      - name: "Build container image"
+        run: |
+          docker build --tag "ghcr.io/${IMAGE_NAME}:${IMAGE_TAG}" .
+
+      - name: "GHCR login"
+        uses: "docker/login-action@v2"
+        with:
+          registry: "ghcr.io"
+          username: "${{ github.repository_owner }}"
+          password: "${{ secrets.GITHUB_TOKEN }}"
+
+      - name: "Push to image registries (DockerHub, GHCR)"
+        run: |
+          # Push to GHCR
+          docker push "ghcr.io/${IMAGE_NAME}:${IMAGE_TAG}"
+
+          # Re-tag image and push to GHCR
+          docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "ghcr.io/${IMAGE_NAME}:${IMAGE_TAG}"
+          docker push "ghcr.io/${IMAGE_NAME}:${IMAGE_TAG}"
+
+          # TODO: quay.io?
+          # docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "quay.io/${IMAGE_NAME}:${IMAGE_TAG}"
+          # docker push "quay.io/${IMAGE_NAME}:${IMAGE_TAG}"