Java

Instrument your Java applications to send traces to Kopai using the OpenTelemetry Java agent.

Java Agent (Recommended)

The OpenTelemetry Java agent provides zero-code instrumentation - no code changes required.

Download the Agent

curl -L -O https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/latest/download/opentelemetry-javaagent.jar

Running Your Application

Set environment variables and run with the agent:

export OTEL_EXPORTER_OTLP_ENDPOINT="https://otlp-http.kopai.app"
export OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer YOUR_TOKEN"
export OTEL_SERVICE_NAME="my-java-service"

java -javaagent:opentelemetry-javaagent.jar -jar your-app.jar

Variable	Description
OTEL_EXPORTER_OTLP_ENDPOINT	Kopai OTLP endpoint
OTEL_EXPORTER_OTLP_HEADERS	Auth header with your backend token
OTEL_SERVICE_NAME	Name shown in Kopai UI

Auto-Instrumentation

The Java agent automatically instruments:

• HTTP - Spring MVC, JAX-RS, Servlet, Netty, OkHttp
• Databases - JDBC, Hibernate, MongoDB, Redis, Cassandra
• Messaging - Kafka, RabbitMQ, JMS
• Frameworks - Spring Boot, Quarkus, Micronaut, Vert.x
• Runtime - JVM metrics, garbage collection, thread pools

See the full list of supported libraries.

Working Example

For a complete working example:

Java Example

Troubleshooting

No traces appearing

1. Verify the agent is loaded: look for [otel.javaagent] in startup logs
2. Check OTEL_EXPORTER_OTLP_ENDPOINT is set correctly
3. Verify token in OTEL_EXPORTER_OTLP_HEADERS

Agent not attaching

• Ensure -javaagent flag comes before -jar
• Check Java version: agent requires Java 8+

Debug logging

Enable agent debug logs:

export OTEL_JAVAAGENT_DEBUG=true

References

• OpenTelemetry Java Getting Started
• Java Agent Releases
• Supported Libraries
• SDK Configuration