Java OTel exemplar working example

gistfile1.txt

package org.example;

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.metrics.LongCounter;
import io.opentelemetry.api.metrics.Meter;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.context.Scope;
import io.opentelemetry.context.Context;
import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporter;
import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.metrics.SdkMeterProvider;
import io.opentelemetry.sdk.metrics.export.MetricExporter;
import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
import io.opentelemetry.sdk.trace.SdkTracerProvider;
import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;

import java.time.Duration;

public class App {

    public static void main(String[] args) throws InterruptedException {
        // Configure OTLP metric exporter to use localhost:4317
        MetricExporter metricExporter = OtlpGrpcMetricExporter.builder()
                .setEndpoint("http://localhost:4317")
                .build();

        PeriodicMetricReader reader = PeriodicMetricReader.builder(metricExporter)
                .setInterval(Duration.ofSeconds(5))
                .build();

        SdkMeterProvider meterProvider = SdkMeterProvider.builder()
                .registerMetricReader(reader)
                .build();

        // Configure OTLP trace exporter to use localhost:4417
        OtlpGrpcSpanExporter spanExporter = OtlpGrpcSpanExporter.builder()
                .setEndpoint("http://localhost:4417")
                .build();

        SdkTracerProvider tracerProvider = SdkTracerProvider.builder()
                .addSpanProcessor(BatchSpanProcessor.builder(spanExporter).build())
                .build();

        // Register the configured OpenTelemetry SDK
        OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
                .setTracerProvider(tracerProvider)
                .setMeterProvider(meterProvider)
                .buildAndRegisterGlobal();

        // Instrumentation
        Tracer tracer = openTelemetry.getTracer("example-instrumentation");
        Meter meter = openTelemetry.getMeter("example-meter");

        LongCounter requestCounter = meter.counterBuilder("example.request_counter")
                .setDescription("Counts incoming requests")
                .setUnit("requests")
                .build();

        // Create a span to provide trace context for the exemplar
        Span span = tracer.spanBuilder("handleRequest").startSpan();
        try (Scope scope = span.makeCurrent()) {
            Attributes attributes = Attributes.builder()
                    .put("endpoint", "/api/resource")
                    .put("status", "200")
                    .build();

            // Record metric with exemplar (auto-attached via span context)
	    requestCounter.add(1, attributes, Context.current());
        } finally {
            span.end();
        }

        // Give time for the exporter to flush
        Thread.sleep(6000);

        // Shut down providers
        tracerProvider.shutdown();
        meterProvider.shutdown();
    }
}