In general, custom metrics are defined as any single, unique combination of a metric name, host, and tag that are sent using statsd, dogstatsd, via API, or through extensions made to the Datadog agent (Further details with examples on how we count a custom metric can be found here). While metrics coming from our vendor-supported integrations are generally not considered custom, there are some exceptions listed below.
Many of the metrics from the following integrations are counted as custom. However, there is a set of standard metrics for each listed at the bottom of their respective docs: ActiveMQ, Go (expvar), Java.
Note: To reduce the chances of unintentionally sending a huge volume of custom metrics to Datadog, we've set a default limit of 350 metrics per host for ActiveMQ_XML, Go_expvar, JMX. This has no effect on what is or is not considered a custom metric. If you'd like to increase this limit, please email email@example.com.