问题
I am trying to integrate fluent-logger-java with a springboot project with a logback appender. And I am able to send data to a fluentd aggregator with the sample code given in https://github.com/fluent/fluent-logger-java
But when added as a logback appender, it throws NullPointerException. I have tried to use logback-more-appenders from https://mvnrepository.com/artifact/com.sndyuk/logback-more-appenders/1.4.3. But it is not sending any data from the application.
To reproduce the issue, generate a simple web project from https://start.spring.io/ with defaults.
Add src\main\java\com\example\demo\FluentLogbackAppender.java to the project
package com.example.demo;
import java.util.HashMap;
import java.util.Map;
import org.fluentd.logger.FluentLogger;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.UnsynchronizedAppenderBase;
public class FluentLogbackAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {
private FluentLogger fluentLogger;
private String label = "test";
@Override
public void start() {
super.start();
this.fluentLogger = FluentLogger.getLogger(label, "localhost", 24224);
Map<String, Object> data = new HashMap<String, Object>();
data.put("msg", "Starting App");
fluentLogger.log(label, data);
}
@Override
protected void append(ILoggingEvent rawData) {
String msg = rawData.toString();
Map<String, Object> data = new HashMap<String, Object>(1);
data.put("msg", msg);
fluentLogger.log(label, data);
}
@Override
public void stop() {
super.stop();
fluentLogger.close();
}
}
Add src\main\resources\logback.xml to the project
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE logback>
<configuration>
<include resource="org/springframework/boot/logging/logback/base.xml"/>
<appender name="fluent" class="com.example.demo.FluentLogbackAppender"/>
<root level="info" additivity="false">
<appender-ref ref="fluent" />
</root>
</configuration>
Adding the dependency in pom.xml
<dependency>
<groupId>org.fluentd</groupId>
<artifactId>fluent-logger</artifactId>
<version>0.3.3</version>
</dependency>
I have stripped some code to make it simple. When running this, I am presented with
2018-05-22 14:39:42.190 ERROR 18788 --- [ main] o.s.boot.SpringApplication : Application run failed
java.lang.IllegalStateException: Logback configuration error detected:
ERROR in ch.qos.logback.core.joran.spi.Interpreter@5:77 - RuntimeException in Action for tag [appender] java.lang.NullPointerException
at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:166)
at org.springframework.boot.logging.logback.LogbackLoggingSystem.reinitialize(LogbackLoggingSystem.java:212)
at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:75)
at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:114)
at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:264)
at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:237)
at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:200)
at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:173)
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:74)
at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:54)
at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:358)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:317)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243)
at com.example.demo.DemoApplication.main(DemoApplication.java:10)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
NullPointerException is returned from sender.emit() inside FluentLogger class. The interesting thing is, this code actually pushes the data to fluentd aggregator just before crash. Is there any way to make this work.
回答1:
I am guessing, you did not paste full code here. I think your class might have getter, setter for tag field. If so then your logback configuration is missing <tag>test</tag> which might be the reason(still guess). FluentLogger has lot of open issues and they recommend to use fluency client library for flushing data to fluentd.
Some references - https://github.com/fluent/fluent-logger-java/issues/72
https://github.com/sndyuk/logback-more-appenders/blob/master/src/main/java/ch/qos/logback/more/appenders/FluencyLogbackAppender.java
https://github.com/komamitsu/fluency
来源：https://stackoverflow.com/questions/50464458/how-to-make-fluent-logger-java-work-with-logback-appender-in-springboot