Cache Docker images

[abrichr]

e.g. docker-build-ec2.yml.j2:

name: Docker Build on EC2 and Publish to GHCR

on:
  push:
    branches:
      - {{ branch_name }}

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: SSH and Execute Build on EC2
        uses: appleboy/ssh-action@master
        with:
          command_timeout: "60m"
          host: {{ host }}
          username: {{ username }}
          {% raw %}
          key: ${{ secrets.SSH_PRIVATE_KEY }}
          {% endraw %}
          script: |
            # Define the image tag
            IMAGE_NAME="ghcr.io/{{ github_owner }}/{{ project_name }}:latest"

            # Check if the image exists on GHCR
            IMAGE_EXISTS=$(curl -s -o /dev/null -w "%{http_code}" https://ghcr.io/v2/{{ github_owner }}/{{ project_name }}/manifests/latest)
            if [ "$IMAGE_EXISTS" -eq 200 ]; then
                echo "Image $IMAGE_NAME already exists in GHCR. Pulling it."

                # Log in to GHCR using secrets passed as environment variables
                echo "${{ secrets.GHCR_PAT }}" | sudo docker login ghcr.io -u "${{ secrets.GHCR_USERNAME }}" --password-stdin

                # Pull the existing image from GHCR
                sudo docker pull $IMAGE_NAME
            else
                echo "Image $IMAGE_NAME does not exist. Proceeding with build and push."

                # Clean up any existing clone
                rm -rf {{ github_repo }} || true
                git clone https://github.com/{{ github_path }}
                cd {{ github_repo }}
                git checkout {{ branch_name }}
                git pull

                # Stop and remove any existing containers
                sudo docker stop {{ project_name }}-container || true
                sudo docker rm {{ project_name }}-container || true

                # Build the Docker image
                sudo nvidia-docker build -t $IMAGE_NAME .

                # Log in to GHCR using secrets passed as environment variables
                echo "${{ secrets.GHCR_PAT }}" | sudo docker login ghcr.io -u "${{ secrets.GHCR_USERNAME }}" --password-stdin

                # Push the Docker image to GHCR
                sudo docker push $IMAGE_NAME
            fi

            # Run the Docker container
            sudo docker stop {{ project_name }}-container || true
            sudo docker rm {{ project_name }}-container || true
            sudo docker run -d -p 7861:7861 --gpus all --name {{ project_name }}-container $IMAGE_NAME