GitHub Actions: add docker image builder

.github/workflows/docker-image.yml

@@ -0,0 +1,34 @@
+name: Docker image
+
+on:
+  push:
+
+jobs:
+  docker-image:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - run: docker build -f .devcontainer/Dockerfile -t btwiuse/arch:${{ github.sha }} .
+      name: docker build
+
+    - name: Login to Docker Hub
+      uses: docker/login-action@v1
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+  # - run: docker push btwiuse/arch:${{ github.sha }}
+  #   name: docker push
+
+  # - run: |
+  #     docker tag btwiuse/arch:${{ github.sha }} btwiuse/arch
+  #     docker push btwiuse/arch
+  #   if: github.ref == 'refs/heads/main'
+  #   name: docker push latest
+
+    - run: |
+        docker tag btwiuse/arch:${{ github.sha }} btwiuse/arch:${{ github.ref_name }}
+        docker push btwiuse/arch:${{ github.ref_name }}
+      name: docker push branch