Is it possible to wildcard logger names in log4net configuration?

Question

In my application, I use log4net, with all types creating their own logger based on their type - e.g. :

private static readonly ILog Log = LogManager.GetLogger(typeof(Program));

As I am developing, I leave the root logger on DEBUG so as to catch all log output from my code.

However, a third party component also uses this same approach, but is generating 100s of log messages a second, none of which I am interested in.

Is it possible to use some sort of wildcarding in the logger configuration, to force all their loggers to only log at WARN, e.g. :

 <logger name="com.thirdparty.*">
    <level value="WARN"/>
  </logger>

[The exact example above, using a * doesn't work]

Answer 1

Can't you do the opposite of what you're asking. What I mean is just set the default log level to warn and then set the specific loggers you have defined to DEBUG.

Also, you could set the threshold of your appender to DEBUG and have the other appender set the WARN.

For example

<appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
    <applicationName value="Application" />
    <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
    </layout>
    <threshold value="WARN" />
</appender>

<appender name="SmtpAppender" type="log4net.Appender.SmtpAppender,log4net">
    <to value="[email protected]" />
    <from value="[email protected]" />
    <subject value="Notification" />
    <smtpHost value="server01" />
    <bufferSize value="1" />
    <lossy value="false" />
    <layout type="log4net.Layout.PatternLayout,log4net">
        <conversionPattern value="%property{log4net:HostName} :: %level :: %message %newlineLogger: %logger%newlineThread: %thread%newlineDate: %date%newlineNDC: %property{NDC}%newline%newline" />
    </layout>
    <threshold value="DEBUG" />
</appender>

Answer 2

You can just specify part of a namespace so it will apply to all messages within that namespace (including nested).

Here is the example I often use:

  <root>
    <level value="FATAL" />
    <appender-ref ref="RollingFile" />
  </root>

  <logger name="MyCompany.Web" >
    <level value="WARN" />
    <appender-ref ref="WebErrors" />
  </logger>

  <!-- Will log all FATALs from NHibernate, including NHibernate.SQL and all the nested -->
  <logger name="NHibernate" >
    <level value="FATAL" />
  </logger>

---

Additionally I would recommend to read the manual. It provides a lot of explanation. For example you can read about Logger Hierarchy. Here is the quote from there:

A logger is said to be an ancestor of another logger if its name followed by a dot is a prefix of the descendant logger name. A logger is said to be a parent of a child logger if there are no ancestors between itself and the descendant logger. The hierarchy works very much in the same way as the namespace and class hierarchy in .NET.

and also:

Level Inheritance: The inherited level for a given logger X, is equal to the first non-null level in the logger hierarchy, starting at X and proceeding upwards in the hierarchy towards the root logger.