blog-2023-09-dynamic-metric.java

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.common.AttributeKey;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporter;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.metrics.SdkMeterProvider;
import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
import io.opentelemetry.sdk.resources.Resource;

import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class DynamicMetric {

    public static void main(String[] args) throws InterruptedException {

        // resource definition - one per service / jvm
        Resource resource = Resource.getDefault()
                .merge(Resource.create(
                        Attributes.of(AttributeKey.stringKey("service.name"), "manualService",
                                AttributeKey.stringKey("service.instance.id"), "myJavaInstance",
                                AttributeKey.stringKey("telemetry.sdk.name"), "opentelemetry-internal")));

        // OTEL SDK initialization - metric only
        SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
                .registerMetricReader(PeriodicMetricReader.builder(OtlpGrpcMetricExporter.builder().build()).build())
                .setResource(resource)
                .build();

        OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
                .setMeterProvider(sdkMeterProvider)
                .buildAndRegisterGlobal();

        // OTEL SDK metric initialization
        openTelemetry.meterBuilder("scopeName").build()
                .gaugeBuilder("my.first.metric")
                .ofLongs()
                .buildWithCallback(longMeasurement -> longMeasurement.record(Math.abs(new Random().nextLong() % 100)));

        // let the program run for a while
        new CountDownLatch(1).await(5, TimeUnit.MINUTES);
    }
}