couch_stats

couch_stats is a simple statistics collection app for Erlang applications. It uses https://www.erlang.org/doc/man/counters.html to implement counters, gauges and histograms. By default histograms record 10 seconds worth of data, with a granularity of 1 second.

Stats can be fetched with couch_stats:fetch(). That returns the current values of all the counters and gauges as well as the histogram statistics for the last 10 seconds.

Adding a metric

1. Write a stat description file. See `priv/descriptions.cfg for an example.

• The metric name should be of type [atom()].
• The type should be one of counter, gauge, or histogram.

If you don‘t add your metric to a description file, your metric will be accessible via couch_stats:sample/1, but it won’t be read by the stats collector and therefore won't be available to HTTP _stats requests, etc.

2. Tell couch_stats to use your description file via application configuration.

3. Instrument your code with the helper functions in couch_stats.erl.