SocketAppender and PatternLayout

Question

I have a logger that send log to a log server storage. This work fine but the patternlayout isn't used. With or without that doesn't change anything. I believe remember to read somewhere that socketappender use is own pattern and not others.

<appender name="LOGSTASH" class="org.apache.log4j.net.SocketAppender"> 
        <param name="Port" value="5000"/>
        <param name="RemoteHost" value="192.168.81.131"/> 
        <param name="ReconnectionDelay" value="5000"/>
        <param name="LocationInfo" value="true" />
      <layout class="org.apache.log4j.PatternLayout">
         <param name="ConversionPattern" value="%d{ABSOLUTE} %-5p [%c{1}] %m%n" />
      </layout>
</appender> 

But on this documentation (and a few other) thay use this. Example from this doc :

<appender name="A1" class="org.apache.log4j.net.SocketAppender">
    <param name="RemoteHost" value="localhost"/>
    <param name="Port" value="5000"/>
    <param name="LocationInfo" value="true"/>
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%t %-5p %c{2} - %m%n"/>
    </layout>
    </appender>

So is it impossible to use personnal pattern with socketappender or is it my fault?

If it's impossible is there an alternative appender for tcp logging with custom pattern?

Answer 1

It seems that SocketAppender don't use a layout.

SocketAppenders do not use a layout. They ship a serialized LoggingEvent object to the server side.

See documentation here

---

So I use a SyslogAppender to replace. It's not perfect because of unused possibilies (like facility and priority) but works fine.

Answer 2

As a workaround,

• For Log4j 1.x
• Copy SocketAppender code to your local project

• Change, "requiresLayout" method as

      public boolean requiresLayout() {
              return true;
      }
  

• Change append method as ;

   public void append(LoggingEvent event) {
  
      ///......
  
      event.getThrowableStrRep();
  
      if (this.layout == null) {
          errorHandler.error("No layout for appender " + name,
                  null, ErrorCode.MISSING_LAYOUT);
          return;
      }
  
      String message = this.layout.format(event);
  
      oos.writeObject(message);
      ///...... 
   }
  

• Set this class as your appender.

• Now on, you can set any layout to this appender.

Hope it helps.

Answer 3

Workaround that @myuce posted is working, but you also need to replace ObjectOutputStream (OOS) within "standard" OutputStream (OS).

You can check inside OOS - it's prepending output with some additional stuff for "the receiver".

??t?{"@timestamp":"2018-03-27T14...

So... I've just replaced (it's scala in my case):

oos = new ObjectOutputStream(new Socket(address, port).getOutputStream()); and oos = new ObjectOutputStream(socket.getOutputStream());

within: stream = new Socket(address, port).getOutputStream and stream = socket.getOutputStream (and variable name [of course every occurrence;] for clarity).