ASP.NET Core 2.2 - Serilog | Missing out on events

Question

New to ASP.NET Core and trying to reuse my already configured Serilog from another [Core] library. Here is my setup -

Test.sln
  Test.Core (project)
      - Serilog init config
      - Autofac dependency injection
      - Other stuff
  Test.WebAPI (project)
      - Configured Autofac module from my Core library in ConfigureContainer method.

Got the base setup figured out. Any services/controllers I make are receiving the dependencies from the registrations I've done in Core library's Autofac module (including the logging as well, but only if I explicitly call _logger.Information / _logger.Debug, etc. and gets printed to both console and log file as configured in Serilog config).

It seems ASP.NET has it's own logger and is using its own logger to log all events, such as these ones - https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-2.2#sample-logging-output

info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET http://localhost:5000/api/todo/0
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[1]
      Executing action method TodoApi.Controllers.TodoController.GetById (TodoApi) with arguments (0) - ModelState is Valid
info: TodoApi.Controllers.TodoController[1002]
      Getting item 0
warn: TodoApi.Controllers.TodoController[4000]
      GetById(0) NOT FOUND

I am trying to re-route events logged by ASP.NET's logger to my own logger and have one logger all around, but cannot figure out how. Can anyone point me in the right direction, please? Thanks in advance!

Answer 1

To "silence" ASP.NET default logs you need to add this to your appsettings.json:

"Logging": {
    "LogLevel": {
      "Default": "Debug",
      "Microsoft": "Warning",
      "System": "Warning"
    }
  }

Then default logger will only log everything with "Warning" or lower levels (there are 6 levels of logs: Trace, Debug, Information, Warning, Error Critical). Also, in order to enable Serilog you just need to add this package:

<PackageReference Include="Serilog.AspNetCore" Version="#version#" />

And add this to your Program.cs:

WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseSerilog(); //this line

Then you can simply inject ILogger<T> with DI and it will use Serilog with your configuration. Also, it will encapsulate your Serilog so later it will be easier to use other logging frameworks

Update: In order to remove previously configured providers try to add this line:

new WebHostBuilder()
.ConfigureLogging(builder => builder.ClearProviders()) // <--here

Answer 2

In my case I have to set Serilog's ILogger from Core library in Startup.cs/Configure() method.

Program.cs

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
          .ConfigureServices(services => services.AddAutofac())
          .UseStartup<Startup>()
          .UseSerilog(); // Added this line as per docs

Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IZLogger zLogger)
{
    ...
    Log.Logger = zLogger.GetCurrentClassLogger<Startup>(); // Set Serilog's ILogger from Core library
    app.UseSerilogRequestLogging(); // Added this line as per docs
    ...
}

Example log:

2019-07-22 19:01:03.179 -04:00 | [INFO] | Request starting HTTP/1.1 GET https://localhost:5001/favicon.ico  
2019-07-22 19:01:03.180 -04:00 | [INFO] | HTTP GET /favicon.ico responded 404 in 0.394846 ms
2019-07-22 19:01:03.181 -04:00 | [INFO] | Request finished in 1.8292ms 404 text/plain