Serilog : RollingFile is not working in asp.net core with 'appsettings.json'

Question

I am using asp.net core(website) and Serilog for logging.

Nuget packages installed are

Serilog
Serilog.AspNetCore
Serilog.Extensions.Logging
Serilog.Extensions.Logging.File
Serilog.Settings.Configuration
Serilog.Sinks.File
Serilog.Sinks.RollingFile
Microsoft.Extensions.Logging

Settings in Main.cs file are :

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
             .ConfigureAppConfiguration((WebHostBuilderContext, configurationBuilder) =>
             {
                 configurationBuilder.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
                 configurationBuilder.AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Production"}.json", optional: true);
                 configurationBuilder.AddEnvironmentVariables();
             })
             .ConfigureLogging((hostingContext, loggingBuilder) =>
             {
                 loggingBuilder.ClearProviders();
                 loggingBuilder.AddSerilog();
             })
            .UseStartup<Startup>();  
}

What is working :

In Startup.cs file if I write following code the logging file is getting created. Here I am specifying the configurations in code itself.

  public void Configure(IApplicationBuilder app,
                                IHostingEnvironment env,
                                ILoggerFactory loggerFactory)
    {
     string logFilePath = Path.Combine(env.ContentRootPath, "Logs/ImportManager2-{Date}.txt");

    Log.Logger = new LoggerConfiguration()
       .MinimumLevel.Debug()
       .WriteTo.RollingFile(logFilePath)
       .CreateLogger();

     loggerFactory.AddSerilog();

     --
     --
    }

When I am using appsettings.json file with following content

{
  "Logging": {
    "LogLevel": {
      "Default": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "MyDatabaseLocal": "Server=_;Database=_;MultipleActiveResultSets=true;Connection Timeout=333;Integrated Security=SSPI",
    "OtherDatabaseLocal": "Server=_;Database=_;MultipleActiveResultSets=true;Connection Timeout=333;Integrated Security=SSPI"
  },
  "Serilog": {
    "MinimumLevel": "Debug",
    "Override": {
      "Microsoft": "Warning"
    },
    "Using": [
      "Serilog.Sinks.Console",
      "Serilog.Sinks.File"
    ],
    "WriteTo": [
      {
        "Name": "RollingFile",
        "Args": {
          "path": "Logs/MyProject.txt"
        }
      }
    ]
  }
}

and changed the startup.cs file like

public void Configure(IApplicationBuilder app,
                            IHostingEnvironment env,
                            ILoggerFactory loggerFactory)
{

 Log.Logger = new LoggerConfiguration()
             .ReadFrom.Configuration(Configuration.GetSection("Serilog"))
             .CreateLogger();

 loggerFactory.AddSerilog();
 --
 --
}

After this there is not file created. What could be the problem.

Answer 1

The following call is not quite working how you're expecting:

.ReadFrom.Configuration(Configuration.GetSection("Serilog"))

When using this extension method, Serilog expects that there will be a section named Serilog within the configuration that you pass through. In your example, you're passing the Serilog section itself, but then it's looking for another Serilog section within that.

Update the call to just pass through Configuration, like this:

.ReadFrom.Configuration(Configuration)

Serilog will find your Serilog section and consume the settings from that.