Extra_applications: not working as intended?


I have a module which needs to use HTTPoison before compile time to configure a module attribute, something like this:

response = HTTPoison.get! url
{:ok, response} = Poison.decode(response.body)
@attr response

I would like to remove the HTTPoison.start() and tried to configure it in extra_applications like this:

extra_applications: [:httpoison],

Doc says:
• :extra_applications - a list of Erlang/Elixir applications that you
want started before your application. For example, Elixir’s :logger or
Erlang’s :crypto. Mix guarantees that any application given here and all of
your runtime dependencies are started before your application starts.

So it looks like its what I need, but it doesnt work

== Compilation error in file lib/module.ex ==
** (ArgumentError) argument error
(stdlib) :ets.lookup_element(:hackney_config, :mod_metrics, 2)
/project/deps/hackney/src/hackney_metrics.erl:27: :hackney_metrics.get_engine/0
/project/deps/hackney/src/hackney_connect.erl:69: :hackney_connect.create_connection/5
/project/deps/hackney/src/hackney_connect.erl:37: :hackney_connect.connect/5
/project/deps/hackney/src/hackney.erl:316: :hackney.request/5
lib/httpoison/base.ex:630: HTTPoison.Base.request/9
lib/httpoison.ex:66: HTTPoison.request!/5
lib/module.ex:4: (module)

what am I missing? cant be done like that? also tried with applications and included_applications with no luck

Applications listed in extra_applications are still started at start up time, not at compile-time.

If you need to use HTTPoison at compile-time, you need to start it at compile time manually.