Can you configure log4net in code instead of using a config file?

Question

I understand why log4net uses app.config files for setting up logging - so you can easily change how information is logged without needing to recompile your code. But in my case I do not want to pack a app.config file with my executable. And I have no desire to modify my logging setup.

Is there a way for me to set up logging in code rather than using the app.config?

Here is my simple config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>
  <log4net>
    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="Logs\EventLog.txt" />
      <appendToFile value="false" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="5" />
      <maximumFileSize value="1GB" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
      </layout>
    </appender>
    <appender name="MemoryAppender" type="log4net.Appender.MemoryAppender">
    </appender>
    <root>
      <level value="Info" />
      <appender-ref ref="RollingLogFileAppender" />
      <appender-ref ref="MemoryAppender" />
    </root>
  </log4net>
</configuration>

EDIT:

To be completely clear: It is my goal to have no XML file. Not even as an embedded resource that I turn into a stream. My goal was to define the logger completely programmatically. Just curious if it's possible and if so where I might find an example of the syntax.

Solution 1

FINAL SOLUTION:₁

For anyone who may stumble upon this in the future, here is what I did. I made the static class below:

using log4net;
using log4net.Repository.Hierarchy;
using log4net.Core;
using log4net.Appender;
using log4net.Layout;

namespace Spectrum.Logging
{
    public class Logger
    {
        public static void Setup()
        {
            Hierarchy hierarchy = (Hierarchy)LogManager.GetRepository();

            PatternLayout patternLayout = new PatternLayout();
            patternLayout.ConversionPattern = "%date [%thread] %-5level %logger - %message%newline";
            patternLayout.ActivateOptions();

            RollingFileAppender roller = new RollingFileAppender();
            roller.AppendToFile = false;
            roller.File = @"Logs\EventLog.txt";
            roller.Layout = patternLayout;
            roller.MaxSizeRollBackups = 5;
            roller.MaximumFileSize = "1GB";
            roller.RollingStyle = RollingFileAppender.RollingMode.Size;
            roller.StaticLogFileName = true;            
            roller.ActivateOptions();
            hierarchy.Root.AddAppender(roller);

            MemoryAppender memory = new MemoryAppender();
            memory.ActivateOptions();
            hierarchy.Root.AddAppender(memory);

            hierarchy.Root.Level = Level.Info;
            hierarchy.Configured = true;
        }
    }
}

And then all I had to do was replace the code where I called the XML file with the following call:

//XmlConfigurator.Configure(new FileInfo("app.config")); // Not needed anymore
Logger.Setup();

---

^{1_{(this answer was edited into the question by the OP, I took the liberty to make it a community answer, see here why)}}

Solution 2

You can also escape XML completely, I wrote a sample with minimal programmatic configuration here.

In a nutshell, here is what you need

var tracer = new TraceAppender();
var hierarchy = (Hierarchy)LogManager.GetRepository();
hierarchy.Root.AddAppender(tracer);
var patternLayout = new PatternLayout {ConversionPattern = "%m%n"};
patternLayout.ActivateOptions();
tracer.Layout = patternLayout;
hierarchy.Configured = true;

Solution 3

Yes, you can configure log4net by calling:

log4net.Config.XmlConfigurator.Configure(XmlElement element)

See the log4net documentation.

Solution 4

Alternatively you could create a custom attribute that inherits from log4net.Config.ConfiguratorAttribute and hard-code you configuration there:

using log4net.Appender;
using log4net.Config;
using log4net.Core;
using log4net.Layout;
using log4net.Repository;
using log4net.Repository.Hierarchy;
using System;
using System.Reflection;

namespace ConsoleApplication1
{
    [AttributeUsage(AttributeTargets.Assembly)]
    public class MyConfiguratorAttribute : ConfiguratorAttribute
    {
        public MyConfiguratorAttribute()
            : base(0)
        {
        }

        public override void Configure(Assembly sourceAssembly, ILoggerRepository targetRepository)
        {
            var hierarchy = (Hierarchy)targetRepository;
            var patternLayout = new PatternLayout();
            patternLayout.ConversionPattern = "%date [%thread] %-5level %logger - %message%newline";
            patternLayout.ActivateOptions();

            var roller = new RollingFileAppender();
            roller.AppendToFile = false;
            roller.File = @"Logs\EventLog.txt";
            roller.Layout = patternLayout;
            roller.MaxSizeRollBackups = 5;
            roller.MaximumFileSize = "1GB";
            roller.RollingStyle = RollingFileAppender.RollingMode.Size;
            roller.StaticLogFileName = true;
            roller.ActivateOptions();
            hierarchy.Root.AddAppender(roller);

            hierarchy.Root.Level = Level.Info;
            hierarchy.Configured = true;
        }
    }
}

Then add the following to a .cs file:

[assembly: ConsoleApplication1.MyConfigurator]

Solution 5

For those who don't want to add appender to Root logger, but to current/other logger:

//somewhere you've made a logger
var logger = LogManager.GetLogger("MyLogger");

// now add appender to it
var appender = BuildMyAppender();
((log4net.Repository.Hierarchy.Logger)logger).AddAppender(appender);

logger.Debug("MyLogger with MyAppender must work now");

// and remove it later if this code executed multiple times (loggers are cached, so you'll get logger with your appender attached next time "MyLogger")
((log4net.Repository.Hierarchy.Logger)logger).RemoveAppender(sbAppender);

View more solutions

Comments

[user20358]

what is the Hierarchy class for?

[Eric Scherrer]

Just a note if you use variables in your roller.File string you can use the log4net.Util.PatternString class to format it before assigning the result to foller.File.

[Philip Bergström]

I ended up getting duplicate log entries using this method. I solved it by adding "hierarchy.Root.RemoveAllAppenders();" to the beginning of the Setup().

[Mickey Perlstein]

From all this, how do i get the ILog ?

[Chris Berry]

@MickeyPerlstein private static readonly ILog Log = LogManager.GetLogger(typeof(YourType));

[Pritam]

How to read the same log file? When i tried to read, it gave the error of The process cannot access the file because it is being used by another process.

[Eivind Gussiås Løkseth]

Doesn't work for me unless I call BasicConfigurator.Configure(hierarchy); instead of just setting hierarchy.Configured = true;.

[Søren Boisen]

@PhilipBergström you're my hero! Finally no more duplicated log output, phew!

[codah]

Trying to use this for Godot engine logging but I'm getting nothing in the logfile. The logfile does get created though. I'm using @EivindGussiåsLøkseth idea but still didn't work..

[Manfred]

Make sure the process that you expect to write to the log file has write permissions in the folder to which you want the log file to be written. To diagnose log4net problems add log4net.Util.LogLog.InternalDebugging = true; before any other log4net call, then run under debugger and inspect the output. log4net will tell you where things go wrong.

[Toby Smith]

Link is now dead

[Joe]

@TobySmith - fixed.

[Raj Kamal]

@codah were you able to solve your problem? I am facing the exact same issue

[codah]

@RajKamal sorry can't remember, haven't used Godot for a long time

[Raj Kamal]

@codah no need. In my case, I needed to create and add [assembly: Repository(<repo name>)] to ensure that log4net uses my configuration. instead of default config

[Andrew Keeton]

Rough F# translation: gist.github.com/akeeton/e97e0eac3a6723e1ff67ca7f3fd47c0c