opentelemetry-java-instrumentation/instrumentation/log4j/log4j-context-data/log4j-context-data-2.17/library-autoconfigure/README.md

ContextData Instrumentation for Log4j2 version 2.17 and higher

This module provides a Log4j2 ContextDataProvider that injects trace context from active spans into log context.

Quickstart

Add these dependencies to your project:

Replace OPENTELEMETRY_VERSION with the latest release.

For Maven, add to your pom.xml dependencies:

<dependencies>
  <dependency>
    <groupId>io.opentelemetry.instrumentation</groupId>
    <artifactId>opentelemetry-log4j-context-data-2.17-autoconfigure</artifactId>
    <version>OPENTELEMETRY_VERSION</version>
    <scope>runtime</scope>
  </dependency>
</dependencies>

For Gradle, add to your dependencies:

runtimeOnly("io.opentelemetry.instrumentation:opentelemetry-log4j-context-data-2.17-autoconfigure:OPENTELEMETRY_VERSION")

Usage

OpenTelemetryContextDataProvider implements the Log4j2 ContextDataProvider SPI, and injects the trace ID and span ID from an active span into Log4j's context data.

Log4j will automatically pick up the integration when you include this module. The following keys will be added to the context when a log statement is made when a span is active:

• trace_id
• span_id
• trace_flags

You can use these keys when defining an appender in your log4j.xml configuration, for example:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout
          pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} trace_id=%X{trace_id} span_id=%X{span_id} trace_flags=%X{trace_flags} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Root>
      <AppenderRef ref="Console" level="All"/>
    </Root>
  </Loggers>
</Configuration>