Aggregate metrics with the Sensu StatsD listener

StatsD is a daemon, tool, and protocol that you can use to send, collect, and aggregate custom metrics. Services that implement StatsD typically expose UDP port 8125 to receive metrics according to the line protocol <metricname>:<value>|<type>.

With StatsD, you can measure anything and everything. Collect custom metrics in your code and send them to a StatsD server to monitor applicaton performance. Monitor CPU, I/O, and network system levels with collection daemons. You can feed the metrics that StatsD aggregates to multiple different backends to store or visualize the data.

Use Sensu to implement StatsD

Sensu implements a StatsD listener on its agents. Each sensu-agent listens on the default port 8125 for UDP messages that follow the StatsD line protocol. StatsD aggregates the metrics, and Sensu translates them to Sensu metrics and events that can be passed to the event pipeline. You can configure the StatsD listener and access it with the netcat utility command:

echo 'abc.def.g:10|c' | nc -w1 -u localhost 8125

Metrics received through the StatsD listener are not stored in etcd. Instead, you must configure event handlers to send the data to a storage solution (for example, a time-series database like InfluxDB).

Configure the StatsD listener

Use flags to configure the Sensu StatsD Server when you start up a sensu-agent.

The following flags allow you to configure event handlers, flush interval, address, and port:

--statsd-disable                      disables the statsd listener and metrics server
--statsd-event-handlers stringSlice   comma-delimited list of event handlers for statsd metrics
--statsd-flush-interval int           number of seconds between statsd flush (default 10)
--statsd-metrics-host string          address used for the statsd metrics server (default "127.0.0.1")
--statsd-metrics-port int             port used for the statsd metrics server (default 8125)

For example:

sensu-agent start --statsd-event-handlers influx-db --statsd-flush-interval 1 --statsd-metrics-host "123.4.5.6" --statsd-metrics-port 8125

Next steps

Now that you know how to feed StatsD metrics into Sensu, check out these resources to learn how to handle the StatsD metrics:

• Handlers reference: in-depth documentation for Sensu handlers
• InfluxDB handler guide: instructions on Sensu’s built-in metric handler