Kafka client collector

Kafka client collector is an implementation of Prometheus custom collector,
for collecting JMX metrics from kafka clients.

Usage

<dependency>
    <groupId>no.sysco.middleware.prometheus</groupId>
    <artifactId>kafka-client-collector</artifactId>
    <version>0.0.5</version>
</dependency>

Prometheus http server

Use KafkaClientsJmxExports to initialize collectors for kafka client’s JMX metrics to conveniently register them.

HTTPServer server = new HTTPServer(8081);
Runtime.getRuntime().addShutdownHook(new Thread(server::stop));
KafkaClientsJmxExports.initialize(kafkaProducer1);

Armeria http server

Add armeria dependency, than

/** init health-check, config, metrics */
final CollectorRegistry collectorRegistry = CollectorRegistry.defaultRegistry;
new ClientsJmxCollector(kafkaProducer).register(collectorRegistry);
Server server = new ServerBuilder().http(8085)
    .service("/", (ctx, req) -> HttpResponse.of("OK"))
    .service("/config", (ctx, req) -> HttpResponse.of(appConfig.properties.toString()))
    .service("/metrics", (ctx, req) -> {
      final ByteArrayOutputStream stream = new ByteArrayOutputStream();
      try (OutputStreamWriter writer = new OutputStreamWriter(stream)) {
        TextFormat.write004(writer, collectorRegistry.metricFamilySamples());
      }
      return HttpResponse.of(HttpStatus.OK, CONTENT_TYPE_004, stream.toByteArray());
    })
    .build();
CompletableFuture<Void> future = server.start();
// Wait until the server is ready.
future.join();

Follow full example

Metric format

JMX example
kafka.producer:type=producer-metrics,client-id="dasf-gdfgd-dfgd-31",waiting-threads="5"
Will be exposed as
producer_metrics_waiting_threads {cliend_id="dasf-gdfgd-dfgd-31"} 5.0

JMX domain (kafka.producer - example above) is not present in Prometheus format, due to kafka-streams api
use others apis (kafka-producer, kafka-consumer, kafka-admin-client) and domain names are not presented in KafkaMetric.

Metrics types (group)

Producer:

• app-info @deprecated
• producer-metrics
• producer-topic-metrics
• producer-node-metrics

  Consumer:

• app-info @deprecated
• consumer-metrics
• consumer-coordinator-metrics
• consumer-fetch-manager-metrics
• consumer-node-metrics

  Stream:

  Stream contains metrics from domains kafka.producer, kafka.consumer, kafka.admin.client and own set of metrics
  such as :
• app-info @deprecated
• stream-metrics [INFO lvl]
• stream-task-metrics [DEBUG lvl]
• stream-processor-node-metrics [DEBUG lvl]
• stream-[store-scope]-metrics [DEBUG lvl]
• stream-record-cache-metrics [DEBUG lvl]
• stream-buffer-metrics [DEBUG lvl]

Prometheus metrics format

1. Check
   Read blog post.
   There is a tool promtool to verify metrics formatting.

References

• More examples
• Issue 305: Add kafka client example config
• Issue 400: does the client automatically publish jmx mertices (heap size memory, thread number)?
• Blog post: JMX monitoring + Java custom metrics.
• Kafka metrics reporter
• IMO - Good example how to make custom collector
• Approaches (POCs) with org.apache.kafka.common.metrics.MetricReporter
  • kafka-prometheus-metric-reporter
  • kafka-client-monitoring-poc
• Micrometer [PR WIP]

Issues

• KIP-488: Clean up Sum,Count,Total Metrics
• KIP-444: Augment metrics for Kafka Streams