How to get runtime config during runtime.exs

Questions / Help
1 
# runtime.exs

config :foo, MyThing, [...]

Application.get_env(:foo, MyThing)

The problem is Application.get_env here only shows the compile time config, not the config that was just set by the config/3 line.

The use case is this… our runtime.exs is really big and messy, so we want to split it up into separate files like so…

if System.get_env("CI") do
  Code.require_file("ci.exs", "config/runtime")
end

The problem is that ci.exs needs to modify connection information (like host/port) for config that was set in runtime.exs.

Is there a good way to do this? Thanks for the help!

2

Gah, I just realized it doesn’t matter. ci.exs can just overwrite whatever it wants, and it doesn’t need to read existing values to do so. Not sure even sure what I was thinking in the first place.

Still, I’m curious why Application.get_env doesn’t get things immediately written by config/3.

3

Because that’s how it works…

defmodule Config do
  defp put_config(value), do: Process.put(@config_key, value)
  def config(root_key, opts) when is_atom(root_key) and is_list(opts) do
    unless Keyword.keyword?(opts) do
      raise ArgumentError, "config/2 expected a keyword list, got: #{inspect(opts)}"
    end

    get_config!()
    |> __merge__([{root_key, opts}])
    |> put_config()
  end
end

So you can access it with Process.get({Config, :config}), but I’d suggest not to do this.