== Embedded mode
Embedded mode allows you to insert Ranch listeners directly
in your supervision tree. This allows for greater fault tolerance
control by permitting the shutdown of a listener due to the
failure of another part of the application and vice versa.
However, just as for non-embedded listeners that were started via
`ranch:start_listener/5`, it is required that the `ranch` application
is running before you can start embedded listeners. Furthermore,
this also means that embedded listeners will restart when `ranch_sup` fails.
WARNING: By using embedded mode, it is possible to start a listener with the same name
as an already existing listener. This will corrupt the information Ranch
keeps for that listener, so you should take care to ensure unique listener
names yourself. A good way to achieve this is by combining the embedded
listener's name with `?MODULE`, or the name of the application it is used
in.
=== Embedding
To embed Ranch in your application you can simply add the child specs
to your supervision tree. This can all be done in the `init/1` function
of one of your application supervisors.
Ranch has a convenience function for getting the listeners child specs
called `ranch:child_spec/5`, that works like `ranch:start_listener/5`,
except that it doesn't start anything, it only returns child specs.
The following example adds one listener to another application's
supervision tree.
.Embed Ranch directly in your supervision tree
[source,erlang]
----
init([]) ->
ListenerSpec = ranch:child_spec({?MODULE, echo},
ranch_tcp, #{socket_opts => [{port, 5555}]},
echo_protocol, []
),
{ok, {#{}, [ListenerSpec]}}.
----
Embedded listeners cannot be stopped via `ranch:stop_listener/1`. Instead,
are to be stopped as part of the shutdown of your application's supervison
tree.
