Wednesday, June 02, 2010

Sample Log4Net Configuration

This sample provides 2 types of loggers – a rolling logfile and an SMTP based logger.

    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="logs//appLog.log"/>
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock"/>
      <appendToFile value="true"/>
      <datePattern value="yyyyMMdd"/>
      <rollingStyle value="Date"/>
      <MaxSizeRollBackups value="180" />
      <filter type="log4net.Filter.LevelRangeFilter">
        <acceptOnMatch value="true"/>
        <levelMin value="DEBUG"/>
        <levelMax value="FATAL"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%-5p %-25d thr:%-5t ${COMPUTERNAME}-[%property{SessionID}] %9rms %c{1},%M: '%m'%n"/>
    <appender name="SmtpAppender" type="log4net.Appender.SmtpAppender">
      <subject value="App Name - Error Log" />
      <smtpHost value="" />
      <from value="fromEmail" />
      <to value="toEmail" />
      <bufferSize value="512" />
      <lossy value="true" />
      <datePattern value="yyyyMMdd"/>
      <threshold value="ERROR" />
      <evaluator type="log4net.Core.LevelEvaluator,log4net">
        <threshold value="ERROR" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="Application Error%newline${COMPUTERNAME} %date %-5level %logger - %message%newline%newline%newline" />
      <appender-ref ref="SmtpAppender" />
      <appender-ref ref="RollingLogFileAppender" />


The rolling log file appender is setup to have a minimal lock. This is required if you are using a cluster, otherwise it might be an overkill.

To use the loggers in an app you need to initialize log4Net. I do this in Asp.Net apps in the application startup method using code similar to this:


void Application_Start(object sender, EventArgs e) 
    //the log4net.ConfigurationFile needs to be set as an appsetting in your config file
    //the following code configures log4Net using the log4net.config file settings
    string logFileName = ConfigurationManager.AppSettings["log4Net.ConfigurationFile"];
    if (string.IsNullOrEmpty(logFileName) == false)
        System.IO.FileInfo fi = new System.IO.FileInfo(System.IO.Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, logFileName));
        if (fi != null && fi.Exists)

where log4net.configurationFile is an appSetting in your web.config file pointing to the location of the log4net file.

To use the logger, you first need to get a logger object using the following code:

private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

Logging is performed using the following code:

Log.Debug(“message”) or Log.Error(“message”), etc.

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