如何在.Net Core 中使用不同的第三方记录器登录到文件？ 第三方记录器可能会在应用程序启动时动态更改

Question

Developing simple application which uses Microsoft.Extensions.Logging framework to log information to file by using Log4Net or NLog or SeriLog . For that using below simple code and its working fine.

var factory = new LoggerFactory().AddLog4Net();
//var factory = new LoggerFactory().AddNLog();
//var factory = new LoggerFactory().AddSerilog();
ILogger logger = factory.CreateLogger<Program>();
logger.Log(LogLevel.Debug, "Some message to log");

For the above sample to work i need to add NLog.Extensions.Logging or Serialog.Extensions.Logging or Microsoft.Extensions.Logging.Log4Net.AspNetCore in my sample application.

What my question is, need to build my sample application generically without referring above Nuget packages and based on customer desire they can use or configure NLog or SeriLog third parties to log, it will be decided by some configure file during runtime.

Without compiling my application again, i need to allow customer to use required third party frameworks. My application should read from config file and write log to file by using corresponding frameworks that mentioned in config file.

Hope you can understand my requirement clearly, thanks in advance.

Answer 1

In this case, the logging is not an "external tool", it is a part of the application. That's why you can't implement a "generic" logging, you have to have it compiled into your app. But you are not limited to only one. You could compile in all three of them, and during the startup initialize the one you need based on the configuration

var factory = Configuration["LoggingSystem"] switch
{
    "log4net" => loggerFactory.AddLog4Net(),
    "nlog" => loggerFactory.AddNLog(),
    ...
    _ => throw new Exception()
};

Of course that means your app should reference all the nugets, but that shouldn't be a problem.