Serilog not writing to file with .NET Core 2.2

Question

P.S. The code below works fine. The problem was between the monitor and the chair. Answer by @jpgrassi sent me in the right direction to resolve it.

I have the following in program.cs:

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

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseSerilog((ctx, config) => { config.ReadFrom.Configuration(ctx.Configuration); })
            .UseStartup<Startup>();

}

And in appsettings.json:

{
  "Serilog": {

    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Default": "Information",
        "Microsoft": "Information",
        "System": "Information"
      }
    },

    "WriteTo": [
      {
        "Name": "RollingFile",
        "Args": {
          "pathFormat": "log-{Date}.txt",
        }
      }
    ]
  },

  "AllowedHosts": "*"
}

In the controller, I write out a log _logger.LogWarning("foo");, but the file is not written out anywhere, there aren't any error that I can see.

I've imported following packages from Nuget: Serilog, Serilog.AspNetCore, Serilog.Settings.Configuration, Serilog.Sinks.RollingFile.

What am I missing?

Answer 1

I posted the original answer assuming the problem was the lack of the Using property in the Serilog configuration. I always had it in my projects and it was the only thing missing in OP's settings. But, after posting the answer I tried different configuration alternatives, including the same as in the question and the logs were still being produced. Reading more, I found out that the Using property is not necessary. From the serilog-settings-configuration package:

(This package implements a convention using DependencyContext to find any package with Serilog anywhere in the name and pulls configuration methods from it, so the Using example above is redundant.) Source: https://github.com/serilog/serilog-settings-configuration

As it turns out (see question comments) the real issue was log file location and write permissions. Code-wise everything was already working.

I'll keep the original answer here, as a matter of history, but its content does not actually fix anything, as nothing was broken in the first place.

---

Original answer:

I believe the problem is because you did not specify in your appsettings to actually use the RollingFile sink. I just quickly created a new app and it works:

  "Serilog": {
    "Using": [ "Serilog.Sinks.Console", "Serilog.Sinks.RollingFile" ],
    "MinimumLevel": "Debug",
    "WriteTo": [
      { "Name": "Console" },
      {
        "Name": "RollingFile",
        "Args": { "pathFormat": "log-{Date}.txt" }
      }
    ],
    "Properties": {
      "Application": "Sample"
    }
  }

Using the following NuGet packages:

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Serilog.AspNetCore" Version="2.1.1" />
    <PackageReference Include="Serilog.Settings.Configuration" Version="3.0.1" />
    <PackageReference Include="Serilog.Sinks.Console" Version="3.1.1" />
    <PackageReference Include="Serilog.Sinks.RollingFile" Version="3.3.0" />
  </ItemGroup>

This logs to a file in the root directory of the app log-20190304.txt.