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W0011 - Application Get Env

Error​

/app_a/src/main.erl
-module(main).

get_app_b_env() ->
    application:get_env(app_b, key).
%%  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ warning: module `main` belongs to app `app_a`, but reads env for `app_b`

Explanation​

The error message is indicating that a module belonging to an application app_a is attempting at reading the environment for a different application app_b.

Erlang provides an API to access the application environment of a different application from the one the calling module (or, to be more precise, the calling process executing that module) belongs to.

This pattern can lead to subtle bugs since the target application (app_b in the above example) could not yet be loaded at the time of the call or it could be missing from a specific release.

Sometimes accessing another application's environment is a totally acceptable behaviour. In those cases, the warning can be silenced via the standard elp:ignore mechanirm.