We're using an Elixir service to host our Phoenix app. We need to make use of some Python libraries, ideally we want to be able to run Python scripts from within Elixir code using Thrift or Erlports.

I've tried adding pip3 commands to build.sh, but the libraries aren't persisted to the service. They are installed to a directory called /opt/render/.local/lib/python3.7/site-packages which isn't present on the server after it's live.

I know we can use Docker, we just want to use it if possible.