README.md

Micrometer MeterProvider

This utility provides an implementation of MeterProvider which wraps a Micrometer MeterRegistry and delegates the reporting of all metrics through Micrometer. This enables projects which already rely on Micrometer and cannot currently migrate to OpenTelemetry Metrics to be able to report on metrics that are reported through the OpenTelemetry Metrics API.

Usage

Create the MicrometerMeterProvider passing an existing instance of MeterRegistry. Then you can use the OpenTelemetry Metrics MeterProvider API to create instruments.

MeterRegistry meterRegistry = ...;

// create the meter provider
MeterProvider meterProvider = MicrometerMeterProvider.builder(meterRegistry)
    .build();
Meter meter = meterProvider.get("my-app");

// create an instrument
LongCounter counter = meter.counterBuilder("my.counter")
    .build();

// record metrics
count.add(1, Attributes.of(AttributeKey.stringKey("key"), "value"));

Note: Instruments in OpenTelemetry are created without tags, which are reported with each measurement. But tags are required to create Micrometer metrics. Because of this difference the adapter must listen for when measurements are being read by the MeterRegistry in order to call callbacks registered for observable metrics in order to create the Micrometer meters on demand.

By default the MicrometerMeterProvider will create a dummy Metric with the name "otel-polling-meter" which will be used to poll the asynchronous OpenTelemetry instruments as it is measured. However, you can also specify an alternative CallbackRegistrar strategy.

MeterRegistry meterRegistry = ...;

// create the meter provider
MeterProvider meterProvider = MicrometerMeterProvider.builder(meterRegistry)
    .setCallbackRegistrar(ScheduledCallbackRegistrar.builder()
        .setPeriod(Duration.ofSeconds(10L))
        .build())
    .build();
Meter meter = meterProvider.get("my-app");

// create an asynchronous instrument
ObservableDoubleGauge gauge = meter.gaugeBuilder("my.gauge")
    .buildWithCallback(measurement -> {
        // record metrics
        measurement.record(queue.size(), Attributes.of(AttributeKey.stringKey("key"), "value"));
    });

Component owners

• Justin Spindler, Comcast

Learn more about component owners in component_owners.yml.