修改Flume Log4j Appender

自定义Log4j Appender

要修改Flume Log4j Appender的实现，我们先了解一下Log4j Appender是如何自定义的。

自定义log4j appender需要继承log4j公共的基类：AppenderSkeleton

• 打印日志核心方法：abstract protected void append(LoggingEvent event);
• 初始化加载资源：public void activateOptions()，默认实现为空
• 释放资源：public void close()
• 是否需要按格式输出文本：public boolean requiresLayout()
• 正常情况下我们只需要覆盖append方法即可。然后就可以在log4j中使用了

Demo:

1. import org.apache.log4j.AppenderSkeleton;
2. import org.apache.log4j.spi.LoggingEvent;
3.
4. public class HelloAppender extends AppenderSkeleton {
5.
6.     private String account ;
7.
8.     @Override
9.     protected void append(LoggingEvent event) {
10.         System.out.println("Hello, " + account + " : "+ event.getMessage());
11.     }
12.
13.     @Override
14.     public void close() {
15.         // TODO Auto-generated method stub
16.
17.     }
18.
19.     @Override
20.     public boolean requiresLayout() {
21.         // TODO Auto-generated method stub
22.         return false;
23.     }
24.
25.     public String getAccount() {
26.         return account;
27.     }
28.
29.     public void setAccount(String account) {
30.         this.account = account;
31.     }
32. }

1. public static void main(String[] args) {
2.     Log log = LogFactory.getLog("helloLog") ;
3.     log.info("I am ready.") ;
4. }

log4j.properties 配置

1
2
3
4

log4j.logger.helloLog=INFO, hello

log4j.appender.hello=HelloAppender
log4j.appender.hello.account=World

执行main函数，输出结果 Hello, World : I am ready.

修改FLume Log4j Appender

Event Header加入appname,hostname,logtype

由于hostname,logtype是固定不变的。所以直接写死在代码中。appname则用log4j.properties进行配置 – appname在log4j.properties中配置,添加：

1
2

#应用程序名
log4j.appender.flume.Appname = 91pc

• 在Log4jAppender类中添加：

1
2
3
4
5
6
7
8
9

private String appname;

public String getAppname() {
  return appname;
}

public void setAppname(String appname) {
  this.appname = appname;
}

• hostname,logtype在Log4jAppender类中添加

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

//author:scy
try {
  hdrs.put("hostname", InetAddress.getLocalHost()+"");
} catch (UnknownHostException e1) {
      String msg = "Cant't get localhost IP";
      LogLog.error(msg);
      if (unsafeMode) {
        return;
      }
      throw new FlumeException(msg + " Exception follows.", e1);
}
//author:scy Need to alarm(>Info)
if(event.getLevel().toInt() > 20000){
  hdrs.put("logtype", "alarm");
}else{
  hdrs.put("logtype", "log4j");
}

Flume Log4j Appender添加log4j的异常详细信息

由于Flume Log4j Appender并没有将Log4j的错误异常栈详细信息封装到Event中，不利于我们的告警系统分析原因。 Log4jAppender.append()中添加如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

Event flumeEvent;
Object message = event.getMessage();
if (message instanceof GenericRecord) {
..
} else {
  hdrs.put(Log4jAvroHeaders.MESSAGE_ENCODING.toString(), "UTF8");
  //按照log4j.properties配置格式化日志
  String msg = layout != null ? layout.format(event) : message.toString();

  //author:edwardsbean
  if(layout.ignoresThrowable()) {
      String[] s = event.getThrowableStrRep();
      if (s != null) {
  int len = s.length;
  for(int i = 0; i < len; i++) {
      msg += s[i];
      msg += Layout.LINE_SEP;
  }
    }
  }

  flumeEvent = EventBuilder.withBody(msg, Charset.forName("UTF8"), hdrs);
}
try {
  rpcClient.append(flumeEvent);

日志接收端就可以接受到日志的详细信息：

1
2
3

 [x] Received '2013-12-26 10:38:08 user log detail
 [nd-PC2600/192.168.253.126] FATAL [com.xx.test.Main] java.lang.Exception: error detail
  at com.xx.test.Main.main(Main.java:35)

Posted by EdwardsBean Dec
26th, 2013  Flume