SocketAppender and PatternLayout

问题

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?

回答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.

回答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.

回答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).

来源：https://stackoverflow.com/questions/27230778/socketappender-and-patternlayout

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