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<p>To use this Apache Druid extension, make sure to <a href="/docs/latest/development/extensions.html#loading-extensions">include</a> <code>kafka-emitter</code> extension.</p>
<h2><a class="anchor" aria-hidden="true" id="introduction"></a><a href="#introduction" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Introduction</h2>
<p>This extension emits Druid metrics to <a href="https://kafka.apache.org">Apache Kafka</a> directly with JSON format.<br>
Currently, Kafka has not only their nice ecosystem but also consumer API readily available.
So, If you currently use Kafka, It's easy to integrate various tool or UI
to monitor the status of your Druid cluster with this extension.</p>
<h2><a class="anchor" aria-hidden="true" id="configuration"></a><a href="#configuration" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Configuration</h2>
<p>All the configuration parameters for the Kafka emitter are under <code>druid.emitter.kafka</code>.</p>
<table>
<thead>
<tr><th>property</th><th>description</th><th>required?</th><th>default</th></tr>
</thead>
<tbody>
<tr><td><code>druid.emitter.kafka.bootstrap.servers</code></td><td>Comma-separated Kafka broker. (<code>[hostname:port],[hostname:port]...</code>)</td><td>yes</td><td>none</td></tr>
<tr><td><code>druid.emitter.kafka.metric.topic</code></td><td>Kafka topic name for emitter's target to emit service metric.</td><td>yes</td><td>none</td></tr>
<tr><td><code>druid.emitter.kafka.alert.topic</code></td><td>Kafka topic name for emitter's target to emit alert.</td><td>yes</td><td>none</td></tr>
<tr><td><code>druid.emitter.kafka.producer.config</code></td><td>JSON formatted configuration which user want to set additional properties to Kafka producer.</td><td>no</td><td>none</td></tr>
<tr><td><code>druid.emitter.kafka.clusterName</code></td><td>Optional value to specify name of your druid cluster. It can help make groups in your monitoring environment.</td><td>no</td><td>none</td></tr>
</tbody>
</table>
<h3><a class="anchor" aria-hidden="true" id="example"></a><a href="#example" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Example</h3>
<pre><code class="hljs">druid<span class="hljs-selector-class">.emitter</span><span class="hljs-selector-class">.kafka</span><span class="hljs-selector-class">.bootstrap</span><span class="hljs-selector-class">.servers</span>=hostname1:<span class="hljs-number">9092</span>,hostname2:<span class="hljs-number">9092</span>
druid<span class="hljs-selector-class">.emitter</span><span class="hljs-selector-class">.kafka</span><span class="hljs-selector-class">.metric</span><span class="hljs-selector-class">.topic</span>=druid-metric
druid<span class="hljs-selector-class">.emitter</span><span class="hljs-selector-class">.kafka</span><span class="hljs-selector-class">.alert</span><span class="hljs-selector-class">.topic</span>=druid-alert
druid<span class="hljs-selector-class">.emitter</span><span class="hljs-selector-class">.kafka</span><span class="hljs-selector-class">.producer</span><span class="hljs-selector-class">.config</span>={<span class="hljs-string">"max.block.ms"</span>:<span class="hljs-number">10000</span>}
</code></pre>
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