= ranch:set_transport_options(3)

== Name

ranch:set_transport_options - Set the transport options

== Description

[source,erlang]
----
set_transport_options(Ref       :: ranch:ref(),
                      TransOpts :: ranch:opts())
    -> ok | {error, Reason :: term()}
----

Set the transport options.

The complete set of transport options is replaced. To update a subset of the
transport options, it is recommended to get the current transport options using
link:man:ranch:get_transport_options(3)[ranch:get_transport_options(3)], update
them and then set them back using this function.

Changes to the following options will take effect...

* immediately:
** `max_connections`
** `handshake_timeout`
** `shutdown`
* only after the listener has been suspended and resumed:
** `num_acceptors`
** `num_listen_sockets`
** `post_listen_callback`
** `socket_opts`
* only when the entire listener is restarted:
** `connection_type`
** `num_conns_sups`
** `logger`

== Arguments

Ref::

The listener name.

TransOpts::

The new transport options.

== Return value

The atom `ok` is returned on success.

An error tuple is returned on failure, for example if the given
transport options contain invalid values.

== Changelog

* *2.0*: The restriction that the listener must be suspended
         has been removed.
* *2.0*: The `TransOpts` argument must no longer contain
         Ranch-specific options if given as a list. Use a map.

== Examples

.Set the transport options
[source,erlang]
----
Ref = example,

ok = ranch:suspend_listener(Ref),
ok = ranch:set_transport_options(Ref, TransOpts),
ok = ranch:resume_listener(Ref).
----

.Update the listener TCP port within the `socket_opts` transport option
[source,erlang]
----
Ref = example,

TransOpts0 = ranch:get_transport_options(Ref),
#{socket_opts = SocketOpts0} = TransOpts0,
SocketOpts = [{port, 12345}|proplists:delete(port, SocketOpts0)],
TransOpts = TransOpts0#{socket_opts = SocketOpts},

ok = ranch:suspend_listener(Ref),
ok = ranch:set_transport_options(Ref, TransOpts),
ok = ranch:resume_listener(Ref).
----

== See also

link:man:ranch:suspend_listener(3)[ranch:suspend_listener(3)],
link:man:ranch:resume_listener(3)[ranch:resume_listener(3)],
link:man:ranch:get_transport_options(3)[ranch:get_transport_options(3)],
link:man:ranch:set_max_connections(3)[ranch:set_max_connections(3)],
link:man:ranch:set_protocol_options(3)[ranch:set_protocol_options(3)],
link:man:ranch(3)[ranch(3)]