Simplest correct way to configure log4net for a .Net Core 3.1 application
Editing my answer a little to be clear that Core does NOT include a normal file logger out of the box. My bad. (as of 5/19/2020)
I would recommend using the logging extensions from Microsoft instead of log4net, but this should do for you. Core now comes with a logger and it's pretty nice and plugs in easy for DI, and uses appsettings.json. I can provide a sample of that too if you want. But here's log4net basic example.
Sample console app that loads config from a file (file set to Copy Always)
using log4net.Repository;
using System;
using System.IO;
using System.Reflection;
namespace ConsoleApp1Core
{
class Program
{
private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
static void Main(string[] args)
{
try
{
ILoggerRepository repository = log4net.LogManager.GetRepository(Assembly.GetCallingAssembly());
var fileInfo = new FileInfo(@"log4net.config");
log4net.Config.XmlConfigurator.Configure(repository, fileInfo);
log.Info("test");
Console.WriteLine("press any key");
Console.ReadLine();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine("Press any key to exit");
Console.ReadLine();
}
}
}
}
I was able to respond with the following methods:
1-Install-Package log4net
2-Install-Package MicroKnights.Log4NetAdoNetAppender
3-Install-Package System.Data.SqlClient
First, I have created a Database and Table with this Code:
CREATE DATABSE Log4netDb
CREATE TABLE [dbo].[Log] (
[Id] [int] IDENTITY (1, 1) NOT NULL,
[Date] [datetime] NOT NULL,
[Thread] [varchar] (255) NOT NULL,
[Level] [varchar] (50) NOT NULL,
[Logger] [varchar] (255) NOT NULL,
[Message] [varchar] (4000) NOT NULL,
[Exception] [varchar] (2000) NULL
)
Second, I have created log4net.config File in program . This is a simple configuration with no customization on the log message:
<?xml version="1.0" encoding="utf-8" ?>
<log4net debug="true">
<!-- definition of the RollingLogFileAppender goes here -->
<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="Logs/WebApp.log" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="10MB" />
<staticLogFileName value="true" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<layout type="log4net.Layout.PatternLayout">
<!-- Format is [date/time] [log level] [thread] message-->
<conversionPattern value="[%date] [%level] [%thread] %m%n" />
</layout>
</appender>
<appender name="AdoNetAppender" type="MicroKnights.Logging.AdoNetAppender, MicroKnights.Log4NetAdoNetAppender">
<bufferSize value="1" />
<connectionType value="System.Data.SqlClient.SqlConnection, System.Data" />
<connectionStringName value="log4net" />
<connectionStringFile value="appsettings.json" />
<commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message]) VALUES (@log_date, @thread, @log_level, @logger, @message)" />
<parameter>
<parameterName value="@log_date" />
<dbType value="DateTime" />
<layout type="log4net.Layout.RawTimeStampLayout" />
</parameter>
<parameter>
<parameterName value="@thread" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%thread" />
</layout>
</parameter>
<parameter>
<parameterName value="@log_level" />
<dbType value="String" />
<size value="50" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level" />
</layout>
</parameter>
<parameter>
<parameterName value="@logger" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%logger" />
</layout>
</parameter>
<parameter>
<parameterName value="@message" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%message" />
</layout>
</parameter>
<parameter>
<parameterName value="@exception" />
<dbType value="String" />
<size value="2000" />
<layout type="log4net.Layout.ExceptionLayout" />
</parameter>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="RollingLogFileAppender" />
<appender-ref ref="AdoNetAppender" />
</root>
</log4net>
Third, I have replaced the code below with IHostBuilder
:
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
.ConfigureLogging(logging =>
{
// clear default logging providers
logging.ClearProviders();
logging.AddConsole();
logging.AddDebug();
logging.AddEventLog();
// add more providers here
})
.UseStartup<Startup>();
Fourth, in appsettings.json
I have inserted this code:
{
"connectionStrings": {
"log4net": "Server=MICKO-PC;Database=Log4netDb;Trusted_Connection=True;MultipleActiveResultSets=true"
}
}
At the end, I have used these commands to enjoy logging in
public class ValuesController : Controller
{
private static readonly ILog log = LogManager.GetLogger(typeof(ValuesController));
[HttpPost]
public async Task<IActionResult> Login(string userName, string password)
{
log.Info("Action start");
// More code here ...
log.Info("Action end");
}
// More code here...
}
Good luck.