# Supported Servers

StatsD supports pluggable server modules that listen for incoming
metrics.

StatsD includes the following built-in servers:

* UDP (`udp`): Listens for metrics on a UDP port. One UDP packet contains at
  least one StatsD metric. Multiple metrics can be received in a single packet
  if separated by the \n character.
* TCP (`tcp`): Listens for metrics on a TCP port. Metrics can span multiple TCP
  packets, meaning each metric must be terminated by the \n character when
  received over TCP.

By default, the `udp` server will be loaded automatically. Currently only a
single server can be run at once. To select which server is loaded, set
the `server` configuration variable to the server module to load.

Servers are just npm modules which implement the interface described in
section [Server Interface](./server_interface.md). In order to be able to load the server,
add the module name into the `server` variable in your config. As the name is also
used in the `require` directive, you can load one of the provided servers by
giving the relative path (e.g. `./servers/udp`).