12 Factor App Config. Principle 3 of a 12 factor app is “store config in the environment”. It implies separation of code and config. The idea behind this principle is that an application should be completely independent from its configuration.
Using this approach, you create a single version of your app configured differently via environment variables. App configuration in environment variables:
12 factor apps are designed to run on platforms that orchestrate isolated unix processes.
For (some of these as per the 12 factor principles) 1) they are are easy to change between deploys without changing any code: Unix processes are configured via environment variables. The 12 factor app states that applications should read config from environment variables. 2) unlike config files, there is little chance of them being checked:
