...This is the same as :gun 2.0.0-rc.2, but Hex doesn't let us depend on RC versions for releases. Generate Elixir code from the proto file as protobuf-elixir shows(especially the gRPC Support section). Implement the server-side code and remember to return the expected message types. You can start the gRPC server as a supervised process. First, add GRPC.Server.Supervisor to your supervision tree.
Coherence is a full featured, configurable authentication system
...Comparable to Devise in the Ruby/Rails ecosystem, it offers modular authentication modules like registration, confirmation, password recovery, session tracking, locking, remember-me, and invitations. It also supports token and HTTP Basic authentication and fits into Phoenix via plugs and routes.