Investigate configuration variables in development, staging, and production

[kevinschoonover]

Motivation

The configuration is a key portion of an application that makes it powerful and scaleable while also producing hard challenges like: where did this variable come from? Where is X being defined? Why is my application connecting to localhost instead of the production database?

I want to investigate ways of making this process more seamless through strict data contracts (like ansible or an application throwing an error when a variable is not defined) in production while also allowing a developer to never have to touch any configuration when doing simple development.

Questions

1. How so we pass configuration variables to the applications in production, staging, and development?
2. How to minimize the number of places that a configuration needs to change in order to affect all of the relevant portions of code?
3. Specifically, take a look at setting the database url in ansible
4. How do we move towards a no configuration developer experience in development with a minimum number of configuration changes necessary in production?
5. Should we use env_vars in docker_compose or .env on the local filesystem?
6. Remove environment variables entirely in production by using vault?
7. How do we fail-fast when development variables are missing/make strict contracts that certain variables must be defined for the application to work?