Erlang: when to perform `inets:start()`?

Question

What is the appropriate place for performing inets:start() ?

1. in `applicationname_app\' module?
2. in applicationname_sup superv

Answer 1

If your code is packaged as an application, list inets in the application resource file:

% Filename: ebin/flamingo.app
{application, flamingo,
  [{vsn, "1.0.0"},
   {modules, [flamingo_app,
              flamingo_sup,
              flamingo]},
   {applications, [kernel,
                   stdlib,
                   inets]},
   {mod, {flamingo_app, []}}
  ]}.

Then you can start the application using application:ensure_all_started(flamingo). This ensures that inets is started automatically for you (i.e. there is no need to explicitly call inets:start()).

For example (assuming the *.app file and *.beam files and are in ebin/):

$ erl -pa ebin/
Eshell V9.2  (abort with ^G)
1> application:ensure_all_started(flamingo).
{ok,[inets,flamingo]}