Serilog : Log to different files

Question

I am logging events of all types to single Json file irrespective of LogLevel. Now I have a requirement to log some custom performance counters to a seperate Json file. How can

Answer 1

We can set it up in the configuration files too. Given below is a sample in the appsettings.json to split the log the rolling files based on levels

{
 
  "Serilog": {
    "MinimumLevel": {
      "Default": "Debug",
      "Override": {
        "Default": "Information",
        "Microsoft": "Warning",
        "Microsoft.Hosting.Lifetime": "Information"
      }
    },
    "WriteTo": [
      {
        "Name": "Logger",
        "Args": {
          "configureLogger": {
            "Filter": [
              {
                "Name": "ByIncludingOnly",
                "Args": {
                  "expression": "(@Level = 'Error' or @Level = 'Fatal' or @Level = 'Warning')"
                }
              }
            ],
            "WriteTo": [
              {
                "Name": "File",
                "Args": {
                  "path": "Logs/ex_.log",
                  "outputTemplate": "{Timestamp:o} [{Level:u3}] ({SourceContext}) {Message}{NewLine}{Exception}",
                  "rollingInterval": "Day",
                  "retainedFileCountLimit": 7
                }
              }
            ]
          }
        }
      },
      {
        "Name": "Logger",
        "Args": {
          "configureLogger": {
            "Filter": [
              {
                "Name": "ByIncludingOnly",
                "Args": {
                  "expression": "(@Level = 'Information' or @Level = 'Debug')"
                }
              }
            ],
            "WriteTo": [
              {
                "Name": "File",
                "Args": {
                  "path": "Logs/cp_.log",
                  "outputTemplate": "{Timestamp:o} [{Level:u3}] ({SourceContext}) {Message}{NewLine}{Exception}",
                  "rollingInterval": "Day",
                  "retainedFileCountLimit": 7
                }
              }
            ]
          }
        }
      }
    ],
    "Enrich": [
      "FromLogContext",
      "WithMachineName"
    ],
    "Properties": {
      "Application": "MultipleLogFilesSample"
    }
  }
}

Then, you will only need to modify the CreateHostBuilder method in Program.cs file to read it from the configuration file

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

For more details, refer the post here