Set metadata in user_data for cowboy_metrics_h

Question

I include cowboy_metrics_h into stream_handlers in my cowboy application.

How I can put data in user_data?
Where I should do it?

Answer 1

In documentation says:

The set_options command can be used to add additional metadata in the user_data metric. This can be used for example to add the handler module which was selected by the router. The option to be set is metrics_user_data. It takes a map which will be merged in the existing user_data map.

Example usage set_options:

set_options(<<"metrics_user_data">>, Req, State) ->
  cowboy_req:cast({set_options, #{metrics_user_data => #{handler => ?MODULE}}}, Req),
  {ok, cowboy_req:reply(200, #{}, <<"Hello world!">>, Req), State}.