I got the example working (GitHub - aws-samples/aws-lambda-elixir-runtime: Example implementation of a custom runtime for running Elixir on AWS Lambda. · GitHub). It was a bit of a hassle since I work on a Mac and then you cannot compile and build a release locally as it is a different platform than what Lambda runs on. So, I had to build the release within a Docker container, extract the build artifact and upload that to Lambda.
Just noticed GitHub - alertlogic/erllambda_elixir_example · GitHub does the same.
