Serilog manual / automatic logging to file in .net core 6

Utilizing Serilog in .net core 6 to automatically log events, as well as manual logging if needed.

I will assume you have a working project, I really don’t like to get bogged down showing you how to create a whole site from scratch.

First lets get some downloads out of the way. Go to your NuGet package manager (right click your project > “Manage NuGet Packages”) and install “Serilog.AspNetCore“, “Serilog.Expressions“, and “Serilog.Sinks.Seq“.
Or you can install via command line like below…

dotnet add package Serilog.AspNetCore
dotnet add package Serilog.Expressions
dotnet add package Serilog.Sinks.Seq

Next, lets configure some settings. Go to appsettings.json and replace the default Logging configuration with below…
Your appsettings.json should look something like this.
You can adjust your settings as you please. below I am sending my logging to a file called “Logfile-[date].log”, and storing it in a “Logs” folder.

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Debug",
      "Override": {
        "Microsoft": "Warning",
        "Microsoft.Hosting.Lifetime": "Information"
      }
    },
    "Filter": [
      {
        "Name": "ByExcluding",
        "Args": {
          "expression": "@mt = 'An unhandled exception has occurred while executing the request.'"
        }
      }
    ],
    "WriteTo": [
      {
        "Name": "File",
        "Args": {
          "path": "./logs/Logfile-.log",
          "rollingInterval": "Day",
          "retainedFileCountLimit": 10
        }
      },
      {
        "Name": "Seq",
        "Args": { "serverUrl": http://localhost:7057 }
      }
    ]
  },
  "AllowedHosts": "*",

Next, go to Program.cs and add the following to the top with all the other imports

using Serilog;

Next, in the Configuration Builder section, add the snippet below…

builder.Host.UseSerilog((ctx, lc) => lc
        .WriteTo.Console()
        .ReadFrom.Configuration(ctx.Configuration));

Last settings in Program.cs is to add the following line in your WebApplication before you run your builder…should look like this in the end…

app.UseSerilogRequestLogging(); //Add this line for request logging
app.Run();

That is all the configuration you need to get automatic logging to take place. But we can take it a step forward, and create a class that can handle manually logging as well….

Create a new class, and lets call it “util.cs”. paste the following code in that newly created file.

using Serilog;

namespace Myprogram
{
    public class util
    {
        private static readonly Serilog.ILogger log = Log.ForContext<util>();

        public void insertLog(string message, string level = "INFO")
        {
            switch (level)
            {
                case "INFO":
                    log.Information(message);
                    break;
                case "DEBUG":
                    log.Debug(message);
                    break;             
                case "WARNING":
                    log.Warning(message);
                    break;
                case "ERROR":
                    log.Error(message);
                    break;
                default:
                    log.Information(message);
                    break;
            }
        }
    }
}

Pretty simple stuff here, of course change this as needed. But essentially we created a simple method to call that will log to your log files.

To use this method, simply use the following code anywhere you need…

var log_ = new helper();
log_.insertLog("I am writing to the log!! Wahoo!", "INFO");