Java Example¶

Before using OTEL to send Trace to Datakit, make sure you have configured the collector.

Configuration: Datakit Configuration OTEL

Add Dependencies¶

Add dependencies in pom.xml

    <!-- add opentelemetry  -->
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-sdk</artifactId>
        <version>1.9.0</version>
    </dependency>
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-exporter-otlp</artifactId>
        <version>1.9.0</version>
    </dependency>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-netty-shaded</artifactId>
        <version>1.41.0</version>
    </dependency>
    <dependency>
        <groupId>io.opentelemetry</groupId>
        <artifactId>opentelemetry-semconv</artifactId>
        <version>1.9.0-alpha</version>
    </dependency>
    <!-- use grpc protocol -->
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-protobuf</artifactId>
        <version>1.36.1</version>
    </dependency>

Java Agent Form¶

There are many ways you can start an Agent. Next, we will show you how to start an Agent through environment variables, command line, and Tomcat configuration.

Start in the form of environment variables

$export JAVA_OPTS="-javaagent:PATH/TO/opentelemetry-javaagent.jar"
$ export OTEL_TRACES_EXPORTER=otlp

Command line activation

java -javaagent:opentelemetry-javaagent-1.13.1.jar \
-Dotel.traces.exporter=otlp \
-Dotel.exporter.otlp.endpoint=http://localhost:4317 \
-jar your-server.jar

Tomcat configuration form

cd <tomcat installation directory>
cd bin
vim catalina.sh
# add at second line
CATALINA_OPTS="$CATALINA_OPTS -javaagent:PATH/TO/opentelemetry-javaagent.jar -Dotel.traces.exporter=otlp"; export CATALINA_OPTS

# restart Tomcat

When configuring the field exporter.otlp.endpoint, you can dispense with the configuration and use the default value (localhost: 4317), because Datakit is on the same host as the Java program, and the default port is also 4317.

Java 2: Code Injection Form¶

package com.example;

import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.common.Attributes;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator;
import io.opentelemetry.context.Context;
import io.opentelemetry.context.propagation.ContextPropagators;
import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
import io.opentelemetry.sdk.OpenTelemetrySdk;
import io.opentelemetry.sdk.resources.Resource;
import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
import io.opentelemetry.sdk.trace.SdkTracerProvider;
import io.opentelemetry.sdk.trace.export.BatchSpanProcessor;
import java.util.concurrent.TimeUnit;
import static java.lang.Thread.sleep;


public class otlpdemo {
    public static void main(String[] args) {
        try {
            OtlpGrpcSpanExporter grpcSpanExporter = OtlpGrpcSpanExporter.builder()
                    .setEndpoint("http://127.0.0.1:4317")   // if setEndpoint is configure, http/https must be added
                    .setTimeout(2, TimeUnit.SECONDS)
                    //.addHeader("header1", "1") // 添加 header
                    .build();

            String s = grpcSpanExporter.toString();
            System.out.println(s);
            SdkTracerProvider tracerProvider = SdkTracerProvider.builder()
                    .addSpanProcessor(BatchSpanProcessor.builder(grpcSpanExporter).build())
                    .setResource(Resource.create(Attributes.builder()
                            .put(ResourceAttributes.SERVICE_NAME, "serviceForJAVA")
                            .put(ResourceAttributes.SERVICE_VERSION, "1.0.0")
                            .put(ResourceAttributes.HOST_NAME, "host")
                            .build()))
                    .build();

            OpenTelemetry openTelemetry = OpenTelemetrySdk.builder()
                    .setTracerProvider(tracerProvider)
                    .setPropagators(ContextPropagators.create(W3CTraceContextPropagator.getInstance()))
                    .buildAndRegisterGlobal();
            // .build();

            Tracer tracer = openTelemetry.getTracer("instrumentation-library-name", "1.0.0");
            Span parentSpan = tracer.spanBuilder("parent").startSpan();


            Span childSpan = tracer.spanBuilder("child")
                    .setParent(Context.current().with(parentSpan))
                    .startSpan();
            childSpan.setAttribute("tagsA", "vllelel");
            // do stuff
            sleep(500);    // delay 0.5 second
            for (int i = 0; i < 10; i++) {
                Span childSpan1 = tracer.spanBuilder("child")
                        .setParent(Context.current().with(parentSpan))
                        .startSpan();
                sleep(1000);    // delay 1 second
                System.out.println(i);
                childSpan1.end();
            }
            childSpan.end();
            childSpan.end(0, TimeUnit.NANOSECONDS);
            System.out.println("span end");
            sleep(1000);    //delay 1 second
            parentSpan.end();
            tracerProvider.shutdown();

        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            System.out.println("finally end");
        }
    }
}

View Effect¶

Log in to Guance Cloud and view application performance monitoring -> links -> Click on a single link

In the flame diagram, you can see the execution time, call flow and so on in each module.

Reference¶

Source sample GitHub-OpenTelemetry-Java
Doc