| # 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`. |
