Log4Net - how to properly use PropertyFilter - log4net

Question

Ok, here's the appender:
<appender name="DebugFileAppender" type="log4net.Appender.FileAppender">
<file value="debug.log" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<filter type="log4net.Filter.PropertyFilter">
<Key value="ApplicationName" />
<StringToMatch value="Test Application" />
</filter>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="DEBUG" />
<levelMax value="DEBUG" />
</filter>
<filter type="log4net.Filter.DenyAllFilter" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="Date:%date Thread:[%thread] Level:%-5level Logger:%logger - ApplicationName:%property{ApplicationName}; Message:%message%newline" />
</layout>
</appender>
Now, it seems this would check the ThreadContext.Properties["ApplicationName"] string and if it finds 'Test Application' it would log.
Well, it's logging everything, even if ApplicationName="DoNotLog".
Now, I will freely admit this may be due to the way I'm (attempting) to use Log4Net - I need to expose it to COM, so I've wrapped up a singleton Log4Net instance, and call this from COM:
public void LogDebug(LogCodeSource codeSource, LogExecutionSource execSource, object message, Exception exception = null)
{
// Add the thread context properties for appender filtering purposes
log4net.ThreadContext.Properties["ApplicationName"] = codeSource.ApplicationName;
log4net.ThreadContext.Properties["ComponentName"] = codeSource.ComponentName;
log4net.ThreadContext.Properties["MethodName"] = codeSource.MethodName;
log4net.ThreadContext.Properties["ClientMachineName"] = execSource.ClientMachineName;
log4net.ThreadContext.Properties["ServerMachineName"] = execSource.ServerMachineName;
log4net.ThreadContext.Properties["UserName"] = execSource.UserName;
if (exception == null)
{
LoggerContext.GetInstance.MainLogger.Debug(message);
}
else
{
LoggerContext.GetInstance.MainLogger.Debug(message, exception);
}
}
In my tests, if I call:
var logger = new MyLogger();
logger.LogDebug(new LogCodeSource { ApplicationName = "Test Application", ComponentName = "Test component", MethodName = "Test method" }, new LogExecutionSource { ClientMachineName = "Test client", ServerMachineName = "Test server", UserName = "Test user" }, "Test message");
logger.LogDebug(new LogCodeSource { ApplicationName = "DoNotLog", ComponentName = "Test component", MethodName = "Test method" }, new LogExecutionSource { ClientMachineName = "Test client", ServerMachineName = "Test server", UserName = "Test user" }, "Test message");
In root, I've tried:
<root>
<appender-ref ref="DebugFileAppender" />
</root>
As well as:
<logger name="MyLogger">
<level value="DEBUG" />
<appender-ref ref="DebugFileAppender" />
</logger>
Both logs are showing up in my debug.log file.
Any idea why the property filter isn't preventing DoNotLog from going to debug.log?
Here's what I'm seeing in the log:
Date:2015-12-31 11:11:00,928 Thread:[14] Level:DEBUG Logger:MyLogger - ApplicationName:Test Application; Message:Test message
Date:2015-12-31 11:11:00,942 Thread:[14] Level:DEBUG Logger:MyLogger - ApplicationName:DoNotLog; Message:Test message

Answer 1

What you are after is an AND filter since you want to log all message where ApplicationName matches a particular name AND the level is DEBUG. Unfortunately log4net doesn't ship AND filters out of the box however this SO answer details how to implement one.

Answer 2

Property filter are also available when using Microsoft.Extensions.Logging.Abstraction instead if log4Net directly.
Example:
using (_logger.BeginScope(new[] { new KeyValuePair<string, object>("YourPropertyKey", "YourPropertyValue") }))
{
_logger.LogDebug("My special log with context property set");
}
Then in the config an appender has to be setup for the property and key.
Note there is rexexToMatch in oder to stringToMacth if you want to allow multiple values to a key.
<log4net>
<root>
<level value="ALL" />
<appender-ref ref="property_logger" />
</root>
<appender name="property_logger" type="log4net.Appender.RollingFileAppender">
<file value="logs/my_service.log" />
<appendToFile value="true" />
<rollingStyle value="Date" />
<datePattern value="-yyyyMMdd" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="5MB" />
<preserveLogFileNameExtension value="true" />
<staticLogFileName value="false" />
<filter type="log4net.Filter.PropertyFilter">
<Key value="YourPropertyKey" />
<StringToMatch value="YourPropertyValue" />
</filter>
<filter type="log4net.Filter.DenyAllFilter" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%2thread] %-5level %.50logger - %message%newline" />
</layout>
</appender>
</log4net>