docs: update epmd/distribution docs

Author: doorgan

apps/expert/lib/expert/engine_node.ex

@@ -56,6 +56,13 @@ defmodule Expert.EngineNode do
           state.cookie,
           "--no-halt",
           "-e",
+          # We manually start distribution here instead of using --sname/--name
+          # because those options are not really compatible with `-epmd_module`.
+          # Apparently, passing the --name/-sname options causes the Erlang VM
+          # to start distribution right away before the modules in the code path
+          # are loaded, and it will crash because Forge.EPMD doesn't exist yet.
+          # If we start distribution manually after all the code is loaded,
+          # everything works fine.
           """
           {:ok, _} = Node.start(:"#{Project.node_name(state.project)}", :longnames)
           #{Forge.NodePortMapper}.register()

apps/forge/lib/forge/epmd.ex

@@ -47,7 +47,7 @@ defmodule Forge.EPMD do
   And in another terminal:
 
       $ EXPERT_PARENT_NODE=expert_parent_foo@macstudio EXPERT_PARENT_PORT=52914 \
-          iex --erl "-start_epmd false -epmd_module Elixir.Forge.EPMD -expert parent_port 52914" --sname expert-project-baz
+          iex --erl "-start_epmd false -epmd_module Elixir.Forge.EPMD" --sname expert-project-baz
       iex> Forge.NodePortMapper.register()
 
   If you try `Node.ping(:expert-project-bar@HOSTNAME)` from the last node, it should work.