Serilog: how to write a file with only one level

Question

I've been asked to write log levels Information, Warning and Error in development, but each of them in one separated file, so that I have information.txt containing only Information logs, warning.txt containing only Warning logs, Error.txt containing only Error logs.

This is my implementation at the moment (it works).

In Program.cs:

public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
    .ConfigureWebHostDefaults(webBuilder =>
    {
        webBuilder.UseStartup<Startup>();
        webBuilder.UseSerilog((webHostBuilderContext, loggerConfiguration) =>
        {
            loggerConfiguration.ReadFrom.Configuration(webHostBuilderContext.Configuration);
        });
    });

In appsettings:

"Serilog": {
  "MinimumLevel": "Information",
  "WriteTo": [
    {
      "Name": "Console"
    },
    {
      "Name": "File",
      "Args": {
        "path": "wwwroot/Logs/log.txt",
        "rollingInterval": "Day",
        "reatinedFileCountLimit": 14,
        "restrictedToMinimumLevel": "Information"
      }
    }
  ]
},

I have installed Serilog.Expressions package and read the docs, I know I have to use something like this

"Filters": [
  {
    "Name": "ByIncludingOnly",
    "Args": {
      "expression": "@l = 'Information'"
    }
  }
]

but I can't understand where it should be placed. I've tried placing it in Args or between Args and Name but it doesn't work, can somebody help me?

I already read lots of threads here on stackoverflow but nothing worked :(

Answer 1

This works but not use doc.

using Serilog;
using Serilog.Events;

Log.Logger = new LoggerConfiguration()
    .WriteTo.Logger(l => l
        .Filter.ByIncludingOnly(e => e.Level == LogEventLevel.Information)
        .WriteTo.File(
            path: "information.txt"))

    .WriteTo.Logger(l => l
        .Filter.ByIncludingOnly(e => e.Level == LogEventLevel.Error)
        .WriteTo.File(
            path: "error.txt"))
        .CreateLogger();

Log.Information("test Information");
Log.Error("test Error");

---------------update using appsettings.json--------------
install package Serilog.Expressions

  "Serilog": {
    "WriteTo": [
      {
        "Name": "Logger",
        "Args": {
          "configureLogger": {
            "Filter": [
              {
                "Name": "ByIncludingOnly",
                "Args": {
                  "expression": "@l = 'Information'"
                }
              }
            ],
            "WriteTo": [
              {
                "Name": "File",
                "Args": {
                  "path": "information.txt"
                }
              }
            ]
          }
        }
      },
      {
        "Name": "Logger",
        "Args": {
          "configureLogger": {
            "Filter": [
              {
                "Name": "ByIncludingOnly",
                "Args": {
                  "expression": "@l = 'Error'"
                }
              }
            ],
            "WriteTo": [
              {
                "Name": "File",
                "Args": {
                  "path": "error.txt"
                }
              }
            ]
          }
        }
      }
    ]
  }

Test Result