In this article I've discussed the use of the dev, prod and deploy environments. Then, I've explained how the compile-env tool can be used to generate .env files for each service in each of these environments. The compile-env tool generates these files from a collection of source values (the single source of truth) that are organized in cohesive groups. The value are used in templates that supply the required values (and only those values) to each service in the system. Finally, I've given an example of creating .env files for the dynamic and static use-case in a deploy environment that uses docker-compose.