Elixir: Set cookie and hostname for release created using mix escript.build

Question

When running iex interactively, one can use

iex --cookie <cookie> --name <hostname>

How do I set the same values for cookie and name when running an executable created using mix escript.build?

I figured out that I need to create a vm.args file with the following contents

## Name of the node
-name name@host

## Cookie for distributed erlang
-setcookie cookie

So I created a vm.args file in the same directory as the executable file. But when I print Node.self(), I get :nonode@nohost.

So where do I store vm.args so that it is read by the executable?

Answer 1

As far as I know, vm.args is not read by escripts. You have (at least) 2 options:

1. Set these values in emu_args key passed to escript in project/0 in mix.exs:

   def project do
     [app: :m,
      ...,
      escript: [main_module: M, emu_args: ["-name foo@bar -setcookie baz"]]]
   end
   

2. Parse the CLI arguments and set the values in your main function:

   defmodule M do
     def main([name, cookie]) do
       Node.start String.to_atom(name)
       Node.set_cookie String.to_atom(cookie)
       IO.inspect {Node.self, Node.get_cookie}
     end
   end
   

   $ mix escript.build
   $ ./m foo@bar baz
   {:foo@bar, :baz}