Elixir: Could not find application file: runtime_tools.app

Question

I am using Docker to develop an Elixir umbrella app. I have one umbrella app and inside a Phoenix app. When I start the code locally with mix phx.server everything works. When I do the same inside the Docker container (code is synced via docker-sync ) I get this error:

(Mix) Could not start application runtime_tools: could not find application file: runtime_tools.app

Any idea on how to fix this?

Answer 1

Turns out erlang-runtime-tools was not installed in my docker image. Adding

RUN apk --update add erlang-runtime-tools

to the dockerfile fixed the issue. Thanks @Alexei Sholik for pointing this out.