Configuring log4net with xml file

Question

I tried to configure log4net for logging everything to the console output. I have a config file named Log4Net.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>
  <log4net>
    <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender" >
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
      </layout>
    </appender>
    <root>
      <level value="INFO" />
      <appender-ref ref="ConsoleAppender" />
    </root>
  </log4net>
</configuration>

and I have my main class (just a testing case)

namespace TestLog4Net {
    class Program {
        private static readonly ILog log = LogManager.GetLogger(typeof(Program));

        static void Main(string[] args) {
            log.Info("Info");
            log.Error("Error");
            Console.ReadKey();
        }
    }
}

I added these lines to the AssemblyInfo.cs

[assembly: log4net.Config.XmlConfigurator(
ConfigFile = "Log4Net.config", Watch = true)]

But now nothing is logged, can someone explain this?

Answer 1

I believe the file that you've mentioned in your post is the content of App.config file instead. App.config is the default configuration file for a variety of C# project templates like WinForm application, Console application, etc. So you should consider naming it as App.config in place of Log4Net.config.

In order to have a full fledged understanding, let us go through three possible ways of configuring log4net:

1. If we want to use our application's App.config file to hold the settings of log4net, then we'll have to add the below mentioned declaration in AssemlyInfo.cs file to below line:

   [assembly: log4net.Config.XmlConfigurator(Watch = true)]
   

   App.config will hold the log4net settings like this:

    <?xml version="1.0" encoding="utf-8" ?>
    <configuration>
      <configSections>
        <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
      </configSections>
      <log4net>
        <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender" >
          <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
          </layout>
        </appender>
        <root>
          <level value="INFO" />
          <appender-ref ref="ConsoleAppender" />
        </root>
      </log4net>
    </configuration>
   

2. In some scenario, we might want to use a dedicated file for holding settings of log4net. We can name it e.g. log4net.config or log4net.xml. While creating such a dedicated config file, we need to ensure that log4net is the root tag of the config file (Refer file-snippet):

   <log4net>
        <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender" >
          <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
          </layout>
        </appender>
        <root>
          <level value="INFO" />
          <appender-ref ref="ConsoleAppender" />
        </root>
   </log4net>
   

   In this case, we require following declaration in AssemblyInfo.cs file. Same declaration has been mentioned in the OP's question also:

   [assembly: log4net.Config.XmlConfigurator(ConfigFile = "Log4Net.config", Watch = true)]
   

3. Now the final use-case. Let's say we're having a custom xml file of our own e.g. myCustomSettings.xml which contains log4net setting. In this case log4net tag is present in a custom config file but it is not the root tag of that file (Refer file-snippet)

   <MyCustomSetting>
     <mySection1></mySection1>
     <mySection2></mySection2>
     <log4net>
        <root>
            <level value="ALL" />
            <appender-ref ref="file" />
            <appender-ref ref="console" />
        </root>
        <appender name="console" type="log4net.Appender.ConsoleAppender">
          <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date %level  - %message%newline" />
          </layout>
          <threshold value="Info" />
        </appender>
        <appender name="file" type="log4net.Appender.RollingFileAppender">
           <file value="${PROGRAMDATA}\MyProduct\myLogs.log" />
           <appendToFile value="true" />
           <rollingStyle value="Size" />
           <maxSizeRollBackups value="5" />
           <maximumFileSize value="10MB" />
           <staticLogFileName value="true" />
           <threshold value="Debug" />
           <layout type="log4net.Layout.PatternLayout">
               <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
           </layout>
        </appender>
      </log4net>
    </MyCustomSetting>
   

   In such a case we'll have to configure log4net through C# code at run-time (Refer code-snippet).

    using System.Xml;
   
    var configFilePath = "myCustomSettings.xml";
    var log4netConfig = new XmlDocument();
    log4netConfig.Load(File.OpenRead(configFilePath));
   
    var repo = LogManager.CreateRepository(Assembly.GetEntryAssembly(), typeof(log4net.Repository.Hierarchy.Hierarchy));
   
    var log4NetXml = log4netConfig["MyCustomSetting"]["log4net"];
    log4net.Config.XmlConfigurator.Configure(repo, log4NetXml);
   

   In this case we don't require the declarative configuration in AssemblyInfo.cs file. So please make sure that you've removed it from there:

    //TODO: Remove it
    [assembly: log4net.Config.XmlConfigurator(Watch = true)]
   

Answer 2

Try this custom configuration through code. Worked for me and tested in multiple apps..

string logFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "\\Config\\Log4Net.config");
    FileInfo finfo = new FileInfo(logFilePath);
   log4net.Config.XmlConfigurator.ConfigureAndWatch(finfo); 

I understand it's a very late reply. But will be useful for some right.

Answer 3

When you have log4net config in a separate config file you should not include the configuration and configSections elements. log4net should be the top level element after the xml declartion.