Java

Integration

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.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

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