I’m starting to work on my first real app and can’t quite understand the runtime configuration story. I would like to use a TOML file to hold the configuration data. My plan is to look for this config.toml file in the path $XDG_CONFIG_HOME/my_app/config.toml or perhaps even iterate through $XDG_CONFIG_DIRS appending /myapp/config.toml to each until one is found. If no file is found a default config will be included.

I would like to use the Toml library to parse the config but I’m not following the guidance on organizing the configuration from the docs. I’m also not clear on how one would access the config data later.

From here I gather I need a config/runtime.exs to fetch the configuration data. I assume this is where the code suggested in the Toml docs goes:

# config/runtime.exs

config_providers: [
  {Toml.Provider, [
    path: {:system, "XDG_CONFIG_DIR", "myapp.toml",
    transforms: [...]
  ]}
]

So let’s say I have something like this snippet of the example from the Toml docs:

# This is an example of something that would be ignored
title = "My config file"

# We're expecting something like this:
[myapp]
key = "value"

How do I later access myapp.key to use “value”?

I’m wondering if it’s Applicationg.get_env/3?