This extension emits druid metrics to InfluxDB over HTTP. Currently this emitter only emits service metric events to InfluxDB (See for a list of metrics). When a metric event is fired it is added to a queue of events. After a configurable amount of time, the events on the queue are transformed to InfluxDB’s line protocol and POSTed to the InfluxDB HTTP API. The entire queue is flushed at this point. The queue is also flushed as the emitter is shutdown.

Note that authentication and authorization must be enabled on the InfluxDB server.

All the configuration parameters for the influxdb emitter are under druid.emitter.influxdb.

The syntax of the line protocol is :

<measurement>[,<tag_key>=<tag_value>[,<tag_key>=<tag_value>]] <field_key>=<field_value>[,<field_key>=<field_value>] [<timestamp>]

where timestamp is in nanoseconds since epoch.

This event is parsed into line protocol according to these rules:

• The measurement becomes druid_query since query is the first part of the metric.
• The field is druid_hits since this is the last part of the metric.

This gives the following String which can be POSTed to InfluxDB: "druid_query,service=druid/historical,hostname=historical001,metric=druid_cache_total druid_hits=34787256 1509440946857000000"

The InfluxDB emitter has a white list of dimensions which will be added as a tag to the line protocol string if the metric has a dimension from the white list. The value of the dimension is sanitized such that every occurrence of a dot or whitespace is replaced with a _ .