Serilog and .NET Core Web API log file isn't created

Question

I'm just starting with Serilog. Despite all the code samples/tut's, I've found online I just can't get it to output to file (the file isn't even created). My app is a Web API (.NET Core 3.1), I'm referencing

Serilog.AspNetCore(3.4.0)
Serilog.Settings.Configurations (3.1.0)
Serilog.Sinks.File (4.1.0)

My appsettings.json:

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "Microsoft.Hosting.Lifetime": "Warning",
        "System": "Warning"
      },
      "WriteTo": [
        {
          "Name": "File",
          "Args": {
            "path": "C:\\DEV\\Logs\\mylog.txt",
            "rollingInterval": "Day"
          }
        }
      ]
    }
  },
  "AllowedHosts": "*"
}

My Program.cs

public static void Main(string[] args)
    {
        Serilog.Debugging.SelfLog.Enable(Console.Out);

        //Read Configuration from appSettings
        var config = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json")
            .Build();
        //Initialize Logger
        Log.Logger = new LoggerConfiguration()
            .ReadFrom.Configuration(config)
            .CreateLogger();
        
        try
        {
            CreateHostBuilder(args).Build().Run();
            Log.Information("Application started!");
        }
        catch (Exception e)
        {
            Log.Fatal(e, "Application failed to start.");
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }

My controller

public void Post(SampleRequest request)
{
    Log.Information("Received request {@request}", request);
}

Not even the Selflog is writing anything to Visual Studio output console Serilog.Debugging.SelfLog.Enable(Console.Out);

Ben D · Accepted Answer · 2020-09-11 14:01:18Z

1

Try and enable SelfLog which should help you pinpoint what is going wrong. This call is slightly different to yours.

Add this in Program.cs just after you call .CreateLogger();

Serilog.Debugging.SelfLog.Enable(msg => Debug.WriteLine(msg));

More details - https://github.com/serilog/serilog/wiki/Debugging-and-Diagnostics

I have Serilog logging to a rolling file in a .Net Core 3.1 app.

These are my nuget references:

<PackageReference Include="Serilog" Version="2.9.0" />
<PackageReference Include="Serilog.AspNetCore" Version="3.2.0" />
<PackageReference Include="Serilog.Sinks.RollingFile" Version="3.3.1-dev-00771" />

Also, just noticed you don't seem to have a Using section in your appsettings.json:

"Serilog": {
    "Using": [ "Serilog.Sinks.RollingFile" ],
    "MinimumLevel": "Debug",
    "WriteTo": [
      {
        "Name": "RollingFile",
        "Args": {
          "pathFormat": "C:\\Logs\\ScreenPop\\Log-{Date}.txt"
        }
      }
    ]
  },

edited Sep 11, 2020 at 14:01

answered Sep 11, 2020 at 13:54

Ben D

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3 Comments

cagi Over a year ago

Thx for the fast response. I can't find where exactly, but I read that Using directive in appsettings.json isn't necessary. Nevertheless, I've included it ("Using": [ "Serilog.Sinks.File" ]) alongside with the SelfLog line of code you provided, but still nothing :( . Neither my log file is created nor anything is debugged out to the visual studio console. Am I looking in the right place for selflog debug messages (Output windowin VS)?

Ben D Over a year ago

@cagi yes that is the correct place. This is one downside I have found with Serilog, when it's not working, you get nothing to assist.

Ben D Over a year ago

another idea, does the application have write permissions to the folder?

cagi · Accepted Answer · 2020-09-14 08:00:31Z

0

I figured out what was the problem. I copied settings from some blog and the "WriteTo" element was actually nested inside the "MinimumLevel" one. The correct settings would be:

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "Microsoft.Hosting.Lifetime": "Warning",
        "System": "Warning"
        }
      },
      "WriteTo": [
        {
          "Name": "File",
          "Args": {
            "path": "C:\\DEV\\Logs\\mylog-.txt",
            "rollingInterval": "Day"
          }
        }
      ]
  },
  "AllowedHosts": "*"
}

answered Sep 14, 2020 at 8:00

cagi

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