Setting up basic logging with Serilog

Adding richer logging to dotnet apps with Serilog

Setup

First start off with installing the nuget packages relevant to your solution

• dotnet add package Serilog is the base packages and required for this.
• dotnet add package Serilog.AspNetCore if you’re using dotnet core.
• dotnet add package Serilog.Extensions.Hosting if you want to add logging via the Host dependency container.
• dotnet add package Serilog.Settings.Configuration if you want to pull Serilog configuration from an injected `appsettings.json´ file.

Sinks

Serilog uses systems called sinks to output the logs. For example, the Serilog.Sinks.Console package provides methods and extensions for outputting to the console, and the Serilog.Sinks.File provides methods and extensions for outputting to files. There are more sinks, but these two are the basic ones used.

Configuring the logger

The logger can be configured two ways - programmatically using fluent functions or from the appsettings.json.

appsettings.json configuration

By adding a Serilog entry to your appsettings.json file, you can easily configure and share the logger’s behaviour.

"Serilog": {  
  "MinimumLevel": "Debug",  
  "Using": ["Serilog.Sinks.Console"],  
  "WriteTo": [  
    {      
      "Name": "Console",  
      "Args": {  
        "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level:u3}] {Message:lj}{NewLine}{Exception}"  
      }  
    }  
  ],  
  "Enrich": ["FromLogContext", "WithMachineName", "WithProcessId"]  
}

Here is a basic setup for logging via console. The WriteTo.[n].Args.OutputTemplate defines how your lines of logging will be presented. There are many different tokens and keyworks that the templating can use to customize the output of the console logging.

Registering the logger

WebApplication

In your service registration, you want to add the logger to the app host. The host object is available on the Application builder you’re using, for example in this case the WebApplicationBuilder.

Program.cs

builder.Host.UseSerilog((context, _, configuration) =>  
{  
    configuration        
	    .ReadFrom.Configuration(context.Configuration);  
});

This will then register Serilog to use the settings provided in the appsettings.json that is injected to the configuration.

IHostApplication

For Host applications you configure the Logger property directly on the builder.

Program.cs

builder.Logging.ClearProviders();  
  
var loggingConfig = new LoggerConfiguration()  
    .ReadFrom.Configuration(builder.Configuration)  
    .CreateLogger();  
  
builder.Logging.AddSerilog(loggingConfig);

First the default logging behaviour is cleared, a LoggerConfiguration class is instantiated and the appsettings.json that is injected into the configuration is used. Finally the Serilog logger is created by providing the config.

Usage via dependency injection

Once the logger is configured and registered, it can be injected into other services via construction injection.

MyController.cs

public class MyController : Controller
{
	private readonly ILogger<MyController> _logger;
	
	public MyController(ILogger<MyController> logger)
	{
	    _logger = logger;
	}
 
	[HttpGet]
	public async Task<IActionResult> Get()
	{
	     _logger.LogInformation("MyController Endpoint hit!");
		
	     return Ok("Hello world");
	}
}