You can use environment variables with error messages https://docs.docker.com/compose/environment-variables/ https://docs.docker.com/compose/environment-variab

You can use environment variables with error messages https://docs.docker.com/compose/environment-variables/ https://docs.docker.com/compose/environment-variables/ - `${VARIABLE:?err}` exits with an error message containing err if `VARIABLE` is unset or empty in the environment. - `${VARIABLE?err}` exits with an error message containing err if `VARIABLE` is unset in the environment.