mirror of https://github.com/apache/druid.git
75 lines
4.6 KiB
Markdown
75 lines
4.6 KiB
Markdown
---
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id: influxdb-emitter
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title: "InfluxDB Emitter"
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---
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~ Licensed to the Apache Software Foundation (ASF) under one
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~ regarding copyright ownership. The ASF licenses this file
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To use this Apache Druid (incubating) extension, make sure to [include](../../development/extensions.md#loading-extensions) `druid-influxdb-emitter` extension.
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## Introduction
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This extension emits druid metrics to [InfluxDB](https://www.influxdata.com/time-series-platform/influxdb/) over HTTP. Currently this emitter only emits service metric events to InfluxDB (See [Druid metrics](../../operations/metrics.md) for a list of metrics).
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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
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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.
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Note that authentication and authorization must be [enabled](https://docs.influxdata.com/influxdb/v1.7/administration/authentication_and_authorization/) on the InfluxDB server.
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## Configuration
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All the configuration parameters for the influxdb emitter are under `druid.emitter.influxdb`.
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|Property|Description|Required?|Default|
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|--------|-----------|---------|-------|
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|`druid.emitter.influxdb.hostname`|The hostname of the InfluxDB server.|Yes|N/A|
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|`druid.emitter.influxdb.port`|The port of the InfluxDB server.|No|8086|
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|`druid.emitter.influxdb.databaseName`|The name of the database in InfluxDB.|Yes|N/A|
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|`druid.emitter.influxdb.maxQueueSize`|The size of the queue that holds events.|No|Integer.MAX_VALUE(=2^31-1)|
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|`druid.emitter.influxdb.flushPeriod`|How often (in milliseconds) the events queue is parsed into Line Protocol and POSTed to InfluxDB.|No|60000|
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|`druid.emitter.influxdb.flushDelay`|How long (in milliseconds) the scheduled method will wait until it first runs.|No|60000|
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|`druid.emitter.influxdb.influxdbUserName`|The username for authenticating with the InfluxDB database.|Yes|N/A|
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|`druid.emitter.influxdb.influxdbPassword`|The password of the database authorized user|Yes|N/A|
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|`druid.emitter.influxdb.dimensionWhitelist`|A whitelist of metric dimensions to include as tags|No|`["dataSource","type","numMetrics","numDimensions","threshold","dimension","taskType","taskStatus","tier"]`|
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## InfluxDB Line Protocol
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An example of how this emitter parses a Druid metric event into InfluxDB's [line protocol](https://docs.influxdata.com/influxdb/v1.7/write_protocols/line_protocol_reference/) is given here:
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The syntax of the line protocol is :
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`<measurement>[,<tag_key>=<tag_value>[,<tag_key>=<tag_value>]] <field_key>=<field_value>[,<field_key>=<field_value>] [<timestamp>]`
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where timestamp is in nanoseconds since epoch.
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A typical service metric event as recorded by Druid's logging emitter is: `Event [{"feed":"metrics","timestamp":"2017-10-31T09:09:06.857Z","service":"druid/historical","host":"historical001:8083","version":"0.11.0-SNAPSHOT","metric":"query/cache/total/hits","value":34787256}]`.
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This event is parsed into line protocol according to these rules:
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* The measurement becomes druid_query since query is the first part of the metric.
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* The tags are service=druid/historical, hostname=historical001, metric=druid_cache_total. (The metric tag is the middle part of the druid metric separated with _ and preceded by druid_. Another example would be if an event has metric=query/time then there is no middle part and hence no metric tag)
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* The field is druid_hits since this is the last part of the metric.
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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"`
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The InfluxDB emitter has a white list of dimensions
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which will be added as a tag to the line protocol string if the metric has a dimension from the white list.
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The value of the dimension is sanitized such that every occurrence of a dot or whitespace is replaced with a `_` .
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