README.md

GRPCClientPool Elixir

A connection pooling library to be used along with grpc to create a connection pool of gRPC clients

Installation

The package can be installed with:

def deps do
  [
    {:grpc_client_pool, "~> 0.0.2-beta"}
  ]
end

Usage

1. Follow grpc instructions on how to generate the elixir code
2. Create a module in your app that will act as a client and make it use the connection pool:

defmodule MyApp.GRPCClient do
  use GRPCClientPool,
    otp_app: :my_app
end

3. Configure the client:

config :my_app, MyApp.GRPCClient,
  size: 2,                                  
  max_overflow: 10,
  url: "localhost:50051",
  connect_opts: []

4. Add client requests within your new module:

defmodule MyApp.GRPCClient do
  use GRPCClientPool,
    otp_app: :my_app

  alias GeneratedProto.ApiInput
  alias GeneratedProto.ApiService.Stub

  def remote_function(%ApiInput{} = params) do
    with_channel(fn channel ->
      Stub.remote_function(channel, params)
    end)
  end
end

Options

The available configuration parameters are:

Name	Default	Required	Description
size	2	false	Poolboy size parameter
max_overflow	10	false	Poolboy max_overflow parameter
url	nil	true	The url to be used as first argument of GRPC.Stub.connect/2. Can be either a string or {:system, "ENV"} or {:system, "ENV", "default"} to load the value from an env variable
connect_opts	[]	false	The second argument passed to GRPC.Stub.connect/2
reconnect_interval	5000	false	If the initial connection doesn't succeed, retry after reconnect_interval ms

TODO

• Better naming logic for poolboy's pool
• Tests
• Configurable checkout timeout
• Better way of getting channel
• Handle connection errors
• Module docs