Pheonix Framework Environment Variables

Question

I am just learning Phoenix and Elixir I am confused, what is the best way to handle environment variables for multiple machines and environments? I keep running into different approaches, from using System.get_env, .env files and mentions of Mix env's. I also keep reading about problems compiling env variables at deployment.

Does anyone have an explanation of how Mix variables, system environment variables and possible .env files or .secret files should be used for local development, stage and production servers?

I have been working mostly in Rails and Python recently so that maybe a helpful contextual piece.

Thanks for the help, Cory

Answer 1

I personally stick with what Phoenix is giving you by default, e.g. using config files for different environments. Since config files are meant for application configuration, e.g. configuring database adapters, they are checked into source control. By default, these are controlled by the MIX_ENV environment variable. If you look at the bottom of your main config/config.exs file, you will notice this:

import_config "#{Mix.env}.exs"

From what I understand from the documentation, Mix.env is just a shorthand for getting the MIX_ENV value.

Phoenix comes with config files for "develop", "prod" and "test" (all in the config directory) which you can modify for your own use. You can also easily add more configurations — if you want to have a "staging"-specific configuration, for example, just set MIX_ENV=staging on the relevant server, and create config/staging.exs.

For sensitive information, like API keys, environment variables are better, since they're not checked into source control and can be easily changed. You can access those env variables from within your config files or from anywhere within your application.

Hope that helps!