Micrometer Metrics

Overview

The Helidon Micrometer provider backs the neutral Helidon metrics API and configured metrics publishers. It provides:

• a Micrometer-backed Helidon meter registry for application-specific metrics
• the standard /observe/metrics endpoint, exposed by the metrics observer
• configuration for the Prometheus and OTLP metrics publishers.

Application code which needs direct Micrometer API access can unwrap the Micrometer registry from Helidon's service-owned meter registry.

Maven Coordinates

To use the metrics observer and Micrometer API, add the following dependencies to your project's pom.xml (see Managing Dependencies).

<dependency>
  <groupId>io.helidon.webserver.observe</groupId>
  <artifactId>helidon-webserver-observe-metrics</artifactId>
</dependency>
<dependency>
  <groupId>io.helidon.metrics.providers</groupId>
  <artifactId>helidon-metrics-providers-micrometer</artifactId>
</dependency>

The first dependency adds the metrics observer and the /observe/metrics endpoint. It includes Helidon's Micrometer-based metrics implementation at runtime. The second dependency makes the Micrometer API available when compiling application code which uses Micrometer types directly, as the examples on this page do.

Usage

Application code can create, look up, and update meters programmatically using the Micrometer MeterRegistry API. The Micrometer concepts documentation provides an introduction to Micrometer's interfaces and classes.

The following example obtains Helidon's service-owned Micrometer registry and passes it to an HTTP service.

Register a MeterRegistry-backed Service with the Web Server

MeterRegistry registry = Services.get(io.helidon.metrics.api.MeterRegistry.class)
        .unwrap(MeterRegistry.class);1
MyService myService = new MyService(registry);2

WebServer.builder()
        .routing(r -> r.register("/myapp", myService))3
        .build();

Create and Update Meters in Your Application Service

class MyService implements HttpService {

    final Counter requestCounter;

    MyService(MeterRegistry registry) {
        requestCounter = registry.counter("allRequests");1
    }

    @Override
    public void routing(HttpRules rules) {
        rules
                .any(this::countRequests)2
                .get("/", this::myGet);
    }

    void countRequests(ServerRequest request, ServerResponse response) {
        requestCounter.increment();3
        response.next();
    }

    void myGet(ServerRequest request, ServerResponse response) {
        response.send("OK");
    }
}

Configuration

Helidon's Micrometer support is exposed through the Micrometer-backed metrics publishers. Configure publishers under metrics.publishers or under server.features.observe.observers.metrics.publishers for observer-specific settings. If you do not configure any publishers explicitly, Helidon infers a Prometheus publisher.

Metrics Endpoint

Helidon's metrics observer exposes the service-owned registry through a REST endpoint, by default at /observe/metrics. See the Helidon Metrics documentation for supported response formats and other endpoint behavior.

Override the observer endpoint using its builder or the server.features.observe.observers.metrics.endpoint configuration key:

server:
  features:
    observe:
      observers:
        metrics:
          endpoint: my-metrics

Publisher Configuration

Configure the supported publishers by name:

metrics:
  publishers:
    prometheus:
    otlp:
      url: http://localhost:4318/v1/metrics

Prometheus Publisher Configuration Options

OTLP Publisher Configuration Options

Additional Information

The Micrometer website describes the project and links to further documentation.