As you can see build section references a single Dockerfile because this is a single container application. It's probably not necessary to explain in much detail the content of the sample Dockerfile. Suffice to say we're using a prepared container image from VS Code Remote / GitHub Codespaces Development Container Images. But feel free to use any image you'd like. You can check our tutorial on PHP on docker at -to-php-on-docker-with-visual-studio-code