Develop Reference

How to get Log4Net to use app.config

The Story: I have a WinForms application with multiple assemblies - MainApp and Utilities. I use Utilities for my logging via log4net. All is fine with the world if I use a separate config file for log4net (aka log4net.config) - no issues.
However, IT staff finds it challenging to tweak two .config files (MainApp.exe.config and log4net.config). So, I'm trying to add my log4net config settings into my app.config file. Not having any luck.
I've tried several solutions posted in this forum. This one seemed to experience the same error I get:
log4net configuration - failed to find section
I've tried putting this line in my Utilities:AssemblyInfo.cs
[assembly: log4net.Config.XmlConfigurator(ConfigFile = "MainApp.exe.config", Watch = false)]
In my Utilities module where log4net is referenced, I have this:
const string TEMP_VARIABLE = "TEMP";
string tempDir = Environment.GetEnvironmentVariable( TEMP_VARIABLE );
StringBuilder userTempDirLogFile = new StringBuilder( tempDir );
userTempDirLogFile.Append( #"\" );
userTempDirLogFile.Append( Environment.MachineName );
userTempDirLogFile.Append( "_MAIN_" );
userTempDirLogFile.Append( DateTime.Now.DayOfWeek );
userTempDirLogFile.Append( ".log" );
log4net.GlobalContext.Properties["MainLogFileName"] = userTempDirLogFile.ToString();
StringBuilder utilityLogFile = ( userTempDirLogFile.Replace( "_MAIN_", "_UTILITIES_" ) );
log4net.GlobalContext.Properties["UtilityLogFileName"] = utilityLogFile.ToString();
log4net.Config.XmlConfigurator.Configure();
_mainLogger = LogManager.GetLogger( "MAIN" );
_mainLogger gets this error message:
log4net:ERROR XmlConfigurator: Failed to find configuration section 'log4net' in the application's .config file. Check your .config file for the <log4net> and <configSections> elements. The configuration section should look like: <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net" />
I noticed in log4net source code that log4net.Config.XmlConfigurator.Configure() calls Assembly.GetCallingAssembly(). I've verified that GetCallingAssembly() is indeed MainApp. My program directory contains all necessary files.
This is my app.config
<?xml version="1.0"?>
<configuration>
<!-- configSections MUST be first! -->
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net" />
</configSections>
<log4net>
<appender name="MainLogFile" type="log4net.Appender.RollingFileAppender">
<file type="log4net.Util.PatternString" value="%property{MainLogFileName}"/>
<appendToFile value="false" />
<maximumFileSize value="20MB" />
<maxSizeRollBackups value="3" />
<param name="Encoding" value="unicodeFFFE" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date{ISO8601} %property{messageId} %-5level %message%newline" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<param name="LevelMin" value="ALL" />
<param name="LevelMax" value="OFF" />
</filter>
</appender>
<appender name="UtilityLogFile" type="log4net.Appender.RollingFileAppender">
<file type="log4net.Util.PatternString" value="%property{UtilityLogFileName}"/>
<appendToFile value="false" />
<maximumFileSize value="20MB" />
<maxSizeRollBackups value="3" />
<param name="Encoding" value="unicodeFFFE" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date{ISO8601} %property{messageId} %-5level %message%newline" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<param name="LevelMin" value="ALL" />
<param name="LevelMax" value="OFF" />
</filter>
</appender>
<logger name="MAIN">
<level value="DEBUG" />
<appender-ref ref="MainLogFile" />
</logger>
<logger name="UTILITY">
<level value="DEBUG" />
<appender-ref ref="UtilityLogFile" />
</logger>
</log4net>
<startup>
<!-- Leave sku out so that both 4.0 and 4.5 are supported -->
<supportedRuntime version="v4.0" />
</startup>
<system.windows.forms jitDebugging="true" />
<system.diagnostics>
<trace useGlobalLock="false" />
</system.diagnostics>
<appSettings>
<add key="PRINT_CALL_STACK" value="false"/>
<add key="TRACK_PERFORMANCE" value="false"/>
<add key="USING_TEST_MODE" value="false"/>
<add key="WAIT_FOR_LOGON" value="0"/>
</appSettings>
</configuration>
I figure I'm missing something, but no clue as to what. Thanks for your time.
Note: using VS2013 and log4net 1.2.13.0. Solution targets .NET 4.0 full and x86.

If you want to put everything in your app.config, make sure you have this in the AssemblyInfo.cs:
[assembly: log4net.Config.XmlConfigurator(ConfigFileExtension = "config", Watch = true)]
true or false can be changed if you want to monitor dynamically or not the config file for changes.
and in your config file, make sure you have the appropriate sections. For example in mine I have:
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net>
<appender name="FileAppender" type="log4net.Appender.FileAppender">
<param name="file" value="logs/App.log"/>
<param name="appendToFile" value="True"/>
<param name="encoding" value="utf-8"/>
<param name="staticLogFileName" value="False"/>
<param name="RollingStyle" value="Size"/>
<param name="MaxSizeRollBackups" value="1"/>
<param name="MaxFileSize" value="10485760"/>
<param name="threshold" value="Debug"/>
<layout type="log4net.Layout.PatternLayout">
<param value="%d [%t] %-5p %c{2} - %m%n" name="conversionPattern"/>
</layout>
</appender>
<root>
<level value="INFO" />
<appender-ref ref="FileAppender" />
</root>
</log4net>

If you put log4net configuration setting into the app.config or the web.config file the put into the AssemblyInfo.cs file in the Properties folder of your project the following line:
[assembly: log4net.Config.XmlConfigurator(Watch = true)]
Quote from the manual:
// Configure log4net using the .config file
[assembly: log4net.Config.XmlConfigurator(Watch=true)]
// This will cause log4net to look for a configuration file
// called TestApp.exe.config in the application base
// directory (i.e. the directory containing TestApp.exe)
// The config file will be watched for changes.

The assembly attribute must be in the MainApp project, not in the Utilities project.
As it says in the documentation for assembly attributes
Therefore if you use configuration attributes you must invoke log4net
to allow it to read the attributes. A simple call to
LogManager.GetLogger will cause the attributes on the calling assembly
to be read and processed. Therefore it is imperative to make a logging
call as early as possible during the application start-up, and
certainly before any external assemblies have been loaded and invoked.

log4net enabled, but not creating any files

I've been shown how to use log4net and got a config file to use. I lost this config file and now I cant get it to work. For some reason the guy who configured it could not get it to work while having the configuration info in app.config so he placed it in log4net.config in the output folder.
He then called this when the program started up:
var logConfig = Path.Combine(Path.GetDirectoryName(typeof(App).Assembly.Location), "log4net.config");
var configStream = new FileInfo(logConfig);
log4net.Config.XmlConfigurator.Configure(configStream);
And it worked flawlessly.
Now I got it to work perfectly in a new console project. However allmost all of my projects are addons to another application so my project types are class libraries loaded by this other application (called Revit).
Anyway, so I know that I can log, but just cant get it to work...
This is log4net.config that I use:
<?xml version="1.0" encoding="utf-8" ?>
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<lockingModel type="log4net.Appender.FileAppender+MinimalLock"/>
<file value="logs\" />
<datePattern value="dd.MM.yyyy'.log'" />
<staticLogFileName value="false" />
<appendToFile value="true" />
<rollingStyle value="Composite" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="5MB" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
</layout>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="RollingFileAppender"/>
</root>
</log4net>
Each class that I want to log stuff from declares the an ILog instance on the class level.
Like this:
static private ILog _logger = LogManager.GetLogger(typeof(Program));
The ILog instance reports that all logging is enabled (debug and so on), but there are no files created.
Do I need to do anything else?
Im going nuts here!
Thanks for any help!

It seems you tried a few different ways to configure log4net. If one fails, the best option is to enable log4net debugging to see if your logger is working/crashed. In your app.config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="log4net.Internal.Debug" value="true"/>
</appSettings>
...
<system.diagnostics>
<trace autoflush="true">
<listeners>
<add
name="textWriterTraceListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="C:\tmp\log4net.txt" />
</listeners>
</trace>
</system.diagnostics>
</configuration>
Log4net FAQ

In App.config file you should add this code in order to register the log4net section handler and the log will be generated
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
</configSections>
......
</configuration>
or Check if your AssemblyInfo.cs file has this code :
[assembly: log4net.Config.XmlConfigurator(ConfigFile = "Log4Net.config", Watch = true)]

Not able to get log4net working to write to file

I am using sharpdevelop to create a console application in C#. I have added in the reference for log4net and I added my logging statements while I was writing the code but I never looked at the log file. Now I am done with the code I need to get the log file working. My program runs fine, even the logging statements, but I can't find the log file.
I have tried to cobble together a couple of examples on getting log4net working. I have the lines to read from the configuration and then to instantiate the object, these are the first lines in my program to run:
log4net.Config.XmlConfigurator.Configure();
ILog datalogger = LogManager.GetLogger("myLog"); //initiate the data logger
Then in various places throughout the code I have this:
datalogger.Info(DateTime.Now.ToString() + ": using file: " + ProDirectory.ToString() + #"\" + myProFile.ToString());
I have also put the following in my app.config file:
<appender name="myLogAppender" type="log4net.Appender.RollingFileAppender" >
<file value="myLog.log" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date %level - %message%n" />
</layout>
</appender>
<logger name="myLog">
<level value="All"></level>
<appender-ref ref="myLogAppender" />
</logger>
No matter what I do, I can't see the log file being produced. I have changed the directory and even paused the program to see if I could find a handle open to the log file. Each time I come up empty. Not sure what I could be doing wrong.

not sure if this will help. I also had hard times making log4net work in different scenarios.
I use log4net root xml node to specify the appender. hope it will help.
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="log.txt" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="250KB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="RollingFileAppender" />
</root>
UPDATE
You might also want to check Visual Studio output log. First setup the output log to log "ALL" (somewhere in VS settings). Then you should see exact error message of log4net in the output window of Visual Studio.

Whenever I have had issues with log4net creating the log file, it usually wound up being a file / directory permissions issue.
Change your <file value="log.txt" /> to something that you know will be accessible by the current user / process running devhost.
For example: <file value="%USERPROFILE%\Documents\log.txt" /> will create a log file in the user's My Documents folder. This is a folder that the user has permissions to write data to, and shouldn't give you any troubles with.
For more information on special folder values, see this link.

Looks like I just had to clean up my XML a little, after I did the log file is working fine:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections> <!-- Level 1 -->
<section name="log4net"
type="log4net.Config.Log4NetConfigurationSectionHandler,
log4net"/> <!-- Level 2 -->
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" />
</startup>
<log4net>
<appender name="myLogAppender" type="log4net.Appender.RollingFileAppender" >
<file value="myLog.log" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date %level - %message%n" />
</layout>
</appender>
<logger name="myLog">
<level value="All"></level>
<appender-ref ref="myLogAppender" />
</logger>
</log4net>
</configuration>

Log4net doesn't write to file

I want add new log to file.this is my appender:
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="mylogfile.txt"/>
<appendToFile value="true"/>
<rollingStyle value="Size"/>
<maxSizeRollBackups value="5"/>
<maximumFileSize value="10MB"/>
<staticLogFileName value="true"/>
<filter type="log4net.Filter.StringMatchFilter">
<stringToMatch value="test"/>
</filter>
<filter type="log4net.Filter.StringMatchFilter">
<stringToMatch value="error"/>
</filter>
<filter type="log4net.Filter.DenyAllFilter"/>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %level %logger - %message%newline%exception"/>
</layout>
</appender>
<root>
<level value="All"/>
<appender-ref ref="RollingFileAppender"/>
</root>
and on my class I add
[assembly: XmlConfigurator(Watch = true)]
and I add access everyone for the file but: log4net doesn't write to file. Why?

Log4net fails silently when there's a problem. The design conceit is that no logging is preferable to taking down the application. To figure out what's wrong, turn on Log4net's internal debugging by adding this key to your [app/web].config file:
<appSettings>
<add key="log4net.Internal.Debug" value="true"/>
</appSettings>
The debug messages will be written to the console or to the System.Diagnostics.Trace system. More details from Phill Haack at http://haacked.com/archive/2006/09/26/Log4Net_Troubleshooting.aspx/
There are any number of reasons Log4net might fail. Permissions problems on the log file directory, for starters (especially true for server processes, where your likely running under a restricted set of permissions for security).

You just need to call Configure:
log4net.Config.XmlConfigurator.Configure();
You can see more details here:
Log4net does not write the log file

You need to initialise the logging as the very first step in your app, and from the same assembly that you have the [assembly] tag:
From the docs:
Therefore if you use configuration attributes you must invoke log4net
to allow it to read the attributes. A simple call to
LogManager.GetLogger will cause the attributes on the calling assembly
to be read and processed. Therefore it is imperative to make a logging
call as early as possible during the application start-up, and
certainly before any external assemblies have been loaded and invoked.
Add something like this in your start up code:
LogManager.GetLogger("Initialises logging from assembly attributes");

You should add this config section:
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
</configSections>
to refer the log4net configuration.

unable to write logs to a file using log4net in an ASP.NET Web Forms Site

I'm having a problem logging to a text file using log4net dll.
I'm using vs 2012 express on a windows server 2008 r2 standard (64).
I have preform the following steps:
Open a new asp.net web forms
Install log4net via nuget manager.
in the global.asax file I have this in Application_Start :
log4net.Config.XmlConfigurator.Configure ();
In the web config I have added to the configSections node this line :
< section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
In the web config I have added this section :
<log4net debug="true">
<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="c:\webSite\extraDownloadServerResources\Logs\ALU\log.txt" />
<appendToFile value="true" />
<rollingStyle value="Composite"/>
<datePattern value="yyyyMMdd" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="5MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%n%-5p %d %5rms %-22.22c{1} %-18.18M %n - %m%n" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="RollingLogFileAppender" />
</root>
</log4net>
In a start up page I have fetch instance of the logger :
private static readonly ILog log = LogManager.GetLogger ( System.Reflection.MethodBase.GetCurrentMethod ().DeclaringType );
In the Page_Load I have wrote this line :
log.Debug ( "test" );
I have add to the log.txt file security the Dedualt App Pool user with read/write permissions.
I have ended up with nothing in my log file.
To test the steps I did I have created a new empty web site and follow these steps one by one.
alas (I like this word) this time the log have been written to the file.
Can any one point me to a possible solution ?

To debug issues with log4net configuration you should enable log4net internal debugging.
Inside appSettings add log4net.Internal.Debug key as following:
<appSettings>
<add key="log4net.Internal.Debug" value="true"/>
</appSettings>
This will enable log4net to output all messages to console and to the Trace. To forward all diagnostics messages to file you can add a trace listener:
<system.diagnostics>
<trace autoflush="true">
<listeners>
<add name="textWriterTraceListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="C:\tmp\log4net.txt" />
</listeners>
</trace>
</system.diagnostics>
These snippets were taken directly from the log4net FAQ and here only for quick reference.
This at least will give you understanding of what is going on as you will get error messages.

i have managed to solve my problem.
i have downloaded a tool to monitor all iss trafic.
When monitoring the traffic i saw the user name wasn't defaultAppPool nor AppPoolName.
it was ASP.NET v4.0.
After i granted the permissions and restarted everything , i finally saw some logs in the file...