70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
# Log4j2 Appender
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This module provides a Log4j2 [appender](https://logging.apache.org/log4j/2.x/manual/appenders.html)
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which forwards Log4j2 log events to the
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[OpenTelemetry Log SDK](https://github.com/open-telemetry/opentelemetry-java/tree/main/sdk/logs).
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To use it, add the following modules to your application's classpath.
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Replace `OPENTELEMETRY_VERSION` with the latest
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stable [release](https://search.maven.org/search?q=g:io.opentelemetry.instrumentation).
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**Maven**
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```xml
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<dependencies>
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<dependency>
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<groupId>io.opentelemetry.instrumentation</groupId>
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<artifactId>opentelemetry-log4j-appender-2.17</artifactId>
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<version>OPENTELEMETRY_VERSION</version>
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</dependency>
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</dependencies>
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```
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**Gradle**
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```kotlin
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dependencies {
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runtimeOnly("io.opentelemetry.instrumentation:opentelemetry-log4j-appender-2.17:OPENTELEMETRY_VERSION")
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}
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```
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The following demonstrates how you might configure the appender in your `log4j.xml` configuration:
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<Configuration status="WARN" packages="io.opentelemetry.instrumentation.log4j.appender.v2_17">
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<Appenders>
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<Console name="Console" target="SYSTEM_OUT">
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<PatternLayout
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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"/>
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</Console>
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<OpenTelemetry name="OpenTelemetryAppender"/>
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</Appenders>
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<Loggers>
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<Root>
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<AppenderRef ref="OpenTelemetryAppender" level="All"/>
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<AppenderRef ref="Console" level="All"/>
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</Root>
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</Loggers>
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</Configuration>
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```
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Next, associate the `OpenTelemetryAppender` configured via `log4j2.xml` with
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an `SdkLogEmitterProvider` in your application:
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```
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SdkLogEmitterProvider logEmitterProvider =
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SdkLogEmitterProvider.builder()
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.setResource(Resource.create(...))
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.addLogProcessor(...)
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.build();
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OpenTelemetryAppender.setSdkLogEmitterProvider(logEmitterProvider);
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```
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In this example Log4j2 log events will be sent to both the console appender and
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the `OpenTelemetryAppender`, which will drop the logs until
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`OpenTelemetryAppender.setSdkLogEmitterProvider(..)` is called. Once initialized, logs will be
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emitted to a `LogEmitter` obtained from the `SdkLogEmitterProvider`.
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