Setup Log4net logging on ASP.NET 5

Last modified: June 13, 2021
Step 1

Create an ASP.NET Core MVC application.

Step 2

We need to install log4net nuget packages. You can either install them via nuget package manager or simply edit the log4net_demo.csproj file.

<ItemGroup> <PackageReference Include="log4net" Version="2.0.12" /> <PackageReference Include="Microsoft.Extensions.Logging.Log4Net.AspNetCore" Version="5.0.1" /> </ItemGroup>

log4net log4net

Step 3

Create a file named log4net.config in the root level and copy the below code.

We will saved the log file to "C:\Temp" folder <file value="C:\Temp\" />. The file name has a convention of date <datePattern value="yyyy-MM-dd.'txt'"/> (e.g. 2021-06-13.txt). Every new day new file will create <rollingStyle value="Date"/>. Total number of log files in the folder will be 100 <maxSizeRollBackups value="100"/>. The maximum file size is 100 MB.

<log4net> <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender"> <lockingModel type="log4net.Appender.FileAppender+MinimalLock"/> <file value="C:\Temp\" /> <datePattern value="yyyy-MM-dd.'txt'"/> <staticLogFileName value="false"/> <appendToFile value="true"/> <rollingStyle value="Date"/> <maxSizeRollBackups value="100"/> <maximumFileSize value="100MB"/> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%date [%thread] %-5level App %newline %message %newline %newline"/> </layout> </appender> <root> <level value="ALL"/> <appender-ref ref="RollingLogFileAppender"/> </root> </log4net>
Step 4

In the Program.cs we need to edit main function as below.

public static void Main(string[] args) { XmlDocument log4netConfig = new XmlDocument(); log4netConfig.Load(File.OpenRead("log4net.config")); var repo = log4net.LogManager.CreateRepository(Assembly.GetEntryAssembly(), typeof(log4net.Repository.Hierarchy.Hierarchy)); log4net.Config.XmlConfigurator.Configure(repo, log4netConfig["log4net"]); CreateHostBuilder(args).Build().Run(); }
Step 5

Finally in the startup.cs file, we first inject ILoggerFactory and then add loggerFactory.AddLog4Net();

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerFactory loggerFactory)