CODEWITHSUNDEEP
c#logginglog4netapp-config
xvdiff
xvdiff

Reputation: 2229

Different appenders based on build configuration in log4net

My main application either starts in a console environment or as a Windows Service, based on certain indicators (launch flags, #if directive,...). As long as the application runs in 'production mode', e.g. without a user context as a startup service, I want to log both in a file (info, warnings) as well as into the Windows event log. However when I'm debugging, I want log messages only been carried out to the console window.

Is there any way to achieve this using log4net that doesn't include touching the application configuration during runtime?

Upvotes: 2

Views: 1324

Answers (2)

samy
samy

Reputation: 14972

Frankly the code approach doesn't sound like a very good idea to me, since it hides some behavior to the person that will manage the system in the end. Since you probably have two build configurations (release and debug?) why not use them instead to change the configuration file depending on the build you're doing.

If you really don't want to do this, then here is how to do it: you can set a custom property in the global context of your log4net library

// declare this code as soon as you've determined what context you're in
log4net.GlobalContext.Properties["ApplicationMode"] = "Service";
// or 'Console", with an #IF directive

Then in your log4net configuration, you can filter out the messages that will be caught by your appenders by using the PropertyFilter of log4net

The console appender for your dev:

<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender,log4net">

  <filter type="log4net.Filter.PropertyFilter">
    <key value="ApplicationMode" />
    <stringToMatch value="Console" />
    <acceptOnMatch value="true" />
  </filter>
  <filter type="log4net.Filter.DenyAllFilter" />

  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date %-5level %-25.25logger{1} - %message%newline" />
  </layout>
</appender>

and the file appender for your production

<appender name="FileAppender" type="log4net.Appender.FileAppender,log4net">

  <filter type="log4net.Filter.PropertyFilter">
    <key value="ApplicationMode" />
    <stringToMatch value="Service" />
    <acceptOnMatch value="true" />
  </filter>
  <filter type="log4net.Filter.DenyAllFilter" />

  <file value="mylogfile.txt" />
  <appendToFile value="true" />
  <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />

  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date %-5level %-25.25logger{1} - %message%newline" />
  </layout>
</appender>

Then declare all appenders for your logs:

<root>
  <level value="DEBUG"/>
  <appender-ref ref="FileAppender"/>
  <appender-ref ref="ConsoleAppender"/>
</root>

This will dispatch your message to the correct appender depending on the value that is in the global property. The DenyAllFilter is important; log4net works by letting all messages go through by default, and you only want the messages matching your PropertyFilter

Upvotes: 3

csharptest.net
csharptest.net

Reputation: 64248

All the appenders can be created, modified, or removed programatically. Why not just remove the appenders you want to avoid? This allows you to use the same code for detecting you are debugging and/or running in console.

To programatically disable the appender:

  log4net.Appender.IAppender[] appenders = log4net.LogManager.GetRepository().GetAppenders();

  for (int i = 0; i < appenders.Length; ++i)
  {
        Log4net.Appender.FileAppender appender = appenders[i] as log4net.Appender.FileAppender;
        if (appender != null && appender.Name == "RollingFile")
              appender.Threshold = log4net.Core.Level.Off;
  }

Upvotes: 0

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