tcp_genserver.ex

defmodule TcpUsage do
  use GenServer
  
  defmodule State do
    defstruct socket: nil
  end
  
  def start_link, do: GenServer.start_link(__MODULE__, [])
  
  def init(_) do
    # try to open connection in 100ms, this could be a send or cast
    Process.send_after(self, :connect, 100)
    
    {:ok, %State{}}
  end
  
  def handle_info(:connect, %State{socked: nil} = state) do
    {:noreply, connect(state)}
  end
  def handle_info({:tcp, socket, message}, %State{socket: socket} = state) do
    # do something with message
    {:noreply, state}
  end
  def handle_info({:tcp_closed, socket}, %State{socket: socket} = state) do
    {:noreply, %{state| socket: nil}
  end
  
  defp connect(state) do
    opts = [:binary, packet: :line, active: false, reuseaddr: true, keepalive: true]
    # I would try to move these to your config, and pass them as args into the genserver,
    # Or load them from here with Application.get_env
    case :gen_tcp.connect('10.10.10.10', 1000, opts) do
      {:ok, socket} ->
        %{state| socket: socket}
      {:error, _} ->
        Process.send_after(self(), :connect, 5_000) # maybe do some backoff here, get the wait time from a function
        state
    end
  end
end