How to set credentials on log4net RollingFileAppender to impersonate?

Question

Case

Currently I'm in the process of deploying a WPF-application with log4net logging. In development I had no issues with the RollingFileAppender. However when deployed and started in a Citrix environment, the current user obviously has no permissions to write log files in the application directory.

Questions

• Is it somehow possible to provide credentials to log4net and/or the RollingFileAppender itself to log with a service account?
• If not possible, any ideas for a workaround (except for giving all users permissions on the directory)?

Thanks in advance!

Answer 1

After two years I encountered the same problem again and found a decent and built-in solution. No need for a custom appender anymore!

This solution comes as a configuration property, which log4net calles securityContext and is applyable to each appender. See example below.

<log4net>
   <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
       <filter type="log4net.Filter.LevelRangeFilter">
         <levelMin value="INFO" />
      </filter>

      <file type="log4net.Util.PatternString" value="LogFiles\%date{yyyyMMdd}\%property{log4net:HostName}_%env{username}" />
      <datePattern value=".yyyyMMdd'.log'" />
      <appendToFile value="true" />
      <rollingStyle value="Date" />
      <maxSizeRollBackups value="10" />
      <staticLogFileName value="false" />
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <layout type="log4net.Layout.PatternLayout">
         <conversionPattern value="%date [%3thread] %-5level %logger [%property{NDC}] - %message%newline" />
      </layout>

      <securityContext type="log4net.Util.WindowsSecurityContext">
         <domainName value="**myDomain**"/>
         <userName value="**myUser**" />
         <password value="**mySecretPassword**" />
      </securityContext>
   </appender>

   <appender name="EventLogAppender" type="log4net.Appender.EventLogAppender">
      <filter type="log4net.Filter.LevelRangeFilter">
         <levelMin value="ERROR" />
      </filter>

      <logName value="Application" />
      <applicationName value="**MyAppName**" />
      <Layout type="log4net.Layout.PatternLayout">
         <conversionPattern value="%date [%thread] %-5level %logger{1} - %message%newline" />
      </Layout>

      <securityContext type="log4net.Util.WindowsSecurityContext">
         <domainName value="**myDomain**"/>
         <userName value="**myUser**" />
         <password value="**mySecretPassword**" />
      </securityContext>
   </appender>

   <root>
      <level value="INFO" />
      <appender-ref ref="RollingFileAppender" />
      <appender-ref ref="EventLogAppender" />
   </root>
</log4net>

Answer 2

Im not familiar with Citrix environment, but you can create custom appender, derived from RollingFileAppender:

public class CitrixRollingFileAppender : RollingFileAppender
{
    public string Login { get; set; }
    public string Password { get; set; }    

    protected override void Append(LoggingEvent loggingEvent)
    {
        // use Login and Password here, or authenticate only once when appender created
        base.Append(loggingEvent);
    }
} 

And configuration:

<appender name="citrix" type="YourNamespace.CitrixRollingFileAppender, YourAssembly">
  <file value="citrixlog.txt"/>
  <appendToFile value="true"/>
  <rollingStyle value="Size"/>
  <login value="Foo"/>
  <password value="Bar"/>
  <layout type="log4net.Layout.SimpleLayout"/>
</appender>

UPDATE: You can override such methods like ActivateOptions or OnClose to execute some code after appender was configured, or when it about to close.