Using log4net to log unhandled errors when using OWIN - log4net

Question

Can you point me to some log4net tutorial or samples that logs all unhandled exceptions occurring on my MVC Web Api when using OWIN?
I have a Startup class that configures Castle Windsor and OAuth and I'm not sure how application errors are handled for OWIN enabled applications.
I have tried putting the log4net code in the Application_Error event in global.asax but it never gets executed.
public class WebApiApplication : System.Web.HttpApplication {
protected void Application_Start() {
log4net.Config.XmlConfigurator.Configure();
}
protected void Application_Error(object sender,EventArgs e) {
Exception lastException = Server.GetLastError();
var logger = log4net.LogManager.GetLogger(typeof(WebApiApplication));
logger.Fatal(lastException);
}
}
Any ideas why this is?
EDIT: web.config with log4net configuration:
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net debug="true">
<logger name="SiteWorksAPI">
<level value="Debug" />
<appender-ref ref="EventLogAppender" />
</logger>
<appender name="FileAppender" type="log4net.Appender.FileAppender">
<file value="C:\ProgramData\Site\SiteWorksAPILog.txt" />
<appendToFile value="true" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<immediateFlush value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="============================================================%nLogger = %logger.%nLocation = %location.%nUnique Token = %property{x-fcc-uniquetoken}.%nDate = %date{dd MMM yyyy - HH:mm:ss}.%nMessage = %message%n" />
</layout>
</appender>
<appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
<applicationName value="SiteWorks.API" />
<logname value="SiteWorks API Log" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="Date: %date{dd MMM yyyy - HH:mm:ss} %nMessage: %message %nIdentity: %identity %nUnique Token: %property{x-fcc-uniquetoken} %nChange Time Stamp: %property{x-fcc-changedatetime} %nOriginal Time Stamp: %property{x-fcc-originaltimestamp} %nOriginating System: %property{x-fcc-originatingsystem} %nOriginating User: %property{x-fcc-originatingusername} %nRequest Uri: %property{Request} %nResponse Headers: %property{ResponseHeaders}%nLogger: %logger %nThread: %thread %n%n%exception" />
</layout>
</appender>
</log4net>

Answer 1

You're not seeing any log events because you haven't defined a root logger in your config - the only logger you've defined is called SiteWorksAPI so any loggers you create with any other name - for example, the one named after typeof(WebApiApplication) - will not log anything. If you add a breakpoint on the logging statement you'll see that all log levels are disabled.
The appenders defined in a root logger are inherited by all named appenders (unless the child appenders are defined with additivity = false) - but child appenders set their own log level.
<root>
<level value="Debug" />
<appender-ref ref="EventLogAppender" />
</root>
Edit: there's also another thing to consider - your defined logger only uses the EventLogAppender - note that in order to log to the Event Log, the documentation states EventLogAppender will fail if you try to write using an event source that doesn't exist unless it is running with local administrator privileges but the event source needs to be created by an elevated process.
For testing purposes, you might want to add your FileAppender to the logger.