Prometheus Emitter

This extension exposes Druid metrics for collection by a Prometheus server (). Emitter is enabled by setting druid.emitter=prometheus configs or include prometheus in the composing emitter list.

Configuration

All metric names and labels are reformatted to match Prometheus standards.

• For names: all characters which are not alphanumeric, underscores, or colons (matching [^a-zA-Z_:][^a-zA-Z0-9_:]*) are replaced with _

Metric mapping

For metrics which are emitted from multiple services with different dimensions, the metric name is prefixed with the service name. e.g. "coordinator-segment/count" : { "dimensions" : ["dataSource"], "type" : "gauge" }, "historical-segment/count" : { "dimensions" : ["dataSource", "tier", "priority"], "type" : "gauge" }