Can log4net output Json?

Question

I've seen a couple extensions for log4net that claim to create json to the log file, but the format is never valid json, meaning the collection is not in an array and not coma separated. Am I using it wrong or is there just no way to use log4net with json?

<appender name="SessionFileAppender" type="log4net.Appender.FileAppender">
  <file value="Session.log" />
  <appendToFile value="false" />
  <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
  <layout type='log4net.Layout.SerializedLayout, log4net.Ext.Json'>
    <decorator type='log4net.Layout.Decorators.StandardTypesDecorator, log4net.Ext.Json' />
    <default />
    <remove value='message' />
    <member value='message:messageobject' />
  </layout>
</appender>

Output is:

{"date":"2017-01-29T13:45:50.7345813-05:00","level":"DEBUG","appname":"MyApp.vshost.exe","logger":"MainWindow","thread":"9","ndc":"(null)","message":"Loading new UI instance"}
{"date":"2017-01-29T13:45:50.7380842-05:00","level":"DEBUG","appname":"MyApp.vshost.exe","logger":"MainWindow","thread":"9","ndc":"(null)","message":"Loading internal localization file"}
{"date":"2017-01-29T13:45:50.7510970-05:00","level":"DEBUG","appname":"MyApp.vshost.exe","logger":"MainWindow","thread":"9","ndc":"(null)","message":"Initializing UI"}

which is close, but not really valid json.

Answer 1

download log4net.Ext.Json nuget package

add following config settings to app.config/web.config files

<log4net>
<appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
  <file value="logs\log-file-name.json" />
  <rollingStyle value="Date" />
  <datePattern value="yyyy-MM-dd" />
  <PreserveLogFileNameExtension value="true" />
  <staticLogFileName value="false" />
  <appendToFile value="true" />
  <maxSizeRollBackups value="10" />
  <dateTimeStrategy 
  type="log4net.Appender.RollingFileAppender+UniversalDateTime" />

  <!--text formatted log4net logging-->
  <!--<layout type="log4net.Layout.PatternLayout">
    --><!--check conversion patterns from 
   https://logging.apache.org/log4net/--><!--
    --><!--<conversionPattern value="%utcdate{ABSOLUTE} UTC %c{1} - %m%n" 
  />--><!--
    <conversionPattern value="%date [%thread] %-5level %logger - 
  %message%newline" />
  </layout>-->

  <!--json formatted log4net logging-->
  <layout type="log4net.Layout.SerializedLayout, log4net.Ext.Json">
    <decorator type="log4net.Layout.Decorators.StandardTypesDecorator, 
  log4net.Ext.Json" />
    <member value="date:date" />
    <member value="level:level" />
    <member value="logger:logger" />
    <member value="message:messageObject" />
    <member value="exception:exception" />
  </layout>
</appender>
<root>
  <!--Options are "ALL", "DEBUG", "INFO", "WARN", "ERROR", "FATAL" and 
"OFF".-->
  <level value="DEBUG" />
  <appender-ref ref="RollingFile" />
</root>
</log4net>

here is a sample call with ninject

Kernel = new StandardKernel(); 
Kernel.Bind<ILog>().ToMethod(c => 
LogManager.GetLogger(typeof(YourClassName))).InSingletonScope();
var log = Kernel.Get<ILog>();
log.debug("testing log4net json");