Serilog in .NET Core Web API

Serilog in .NET Core Web API

Logging is a critical aspect of application development as it helps in debugging, monitoring, and maintaining application health. Serilog is a popular structured logging framework for .NET that allows developers to log messages to various destinations (sinks) such as files, databases, and cloud storage. This article will guide you through integrating Serilog into a .NET Core Web API.

Setting Up Serilog in .NET Core Web API

Step 1: Install Required NuGet Packages

To get started with Serilog, install the necessary NuGet packages:

Install-Package Serilog.AspNetCore

Install-Package Serilog.Settings.Configuration

Install-Package Serilog.Sinks.Console

Install-Package Serilog.Sinks.File

These packages allow logging to the console and files while using configurations from appsettings.json.

Step 2: Configure Serilog in Program.cs

Modify the Program.cs file to initialize Serilog:

using Microsoft.AspNetCore.Builder;

using Microsoft.AspNetCore.Hosting;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Hosting;

using Serilog;

using System;

 

var builder = WebApplication.CreateBuilder(args);

 

// Configure Serilog

Log.Logger = new LoggerConfiguration()

    .ReadFrom.Configuration(builder.Configuration)

    .Enrich.FromLogContext()

    .WriteTo.Console()

    .WriteTo.File("logs/log-.txt", rollingInterval: RollingInterval.Day)

    .CreateLogger();

 

builder.Host.UseSerilog();

 

var app = builder.Build();

 

app.UseSerilogRequestLogging(); // Enable request logging

 

app.MapGet("/", () => "Hello, world!");

 

app.Run();

Step 3: Configure appsettings.json

You can configure Serilog settings in appsettings.json:

{

  "Serilog": {

    "Using": ["Serilog.Sinks.Console", "Serilog.Sinks.File"],

    "MinimumLevel": "Information",

    "WriteTo": [

      { "Name": "Console" },

      { "Name": "File", "Args": { "path": "logs/log-.txt", "rollingInterval": "Day" } }

    ],

    "Enrich": ["FromLogContext"],

    "Properties": { "Application": "MyAPI" }

  }

}

Logging in Controllers

Now that Serilog is set up, you can use it in your controllers:

using Microsoft.AspNetCore.Mvc;

using Microsoft.Extensions.Logging;

 

[ApiController]

[Route("api/[controller]")]

public class SampleController : ControllerBase

{

    private readonly ILogger<SampleController> _logger;

 

    public SampleController(ILogger<SampleController> logger)

    {

        _logger = logger;

    }

 

    [HttpGet]

    public IActionResult Get()

    {

        _logger.LogInformation("Handling GET request at {Time}", DateTime.UtcNow);

        return Ok("Logging with Serilog!");

    }

}

Real-Time Example: User Login Logging

Let's implement a real-world scenario where we log user login attempts.

Step 1: Update the Controller

Modify the controller to log login attempts:

[ApiController]

[Route("api/[controller]")]

public class AuthController : ControllerBase

{

    private readonly ILogger<AuthController> _logger;

 

    public AuthController(ILogger<AuthController> logger)

    {

        _logger = logger;

    }

 

    [HttpPost("login")]

    public IActionResult Login([FromBody] LoginRequest request)

    {

        _logger.LogInformation("Login attempt for user: {Username} at {Time}", request.Username, DateTime.UtcNow);

       

        if (request.Username == "admin" && request.Password == "password")

        {

            _logger.LogInformation("Successful login for user: {Username} at {Time}", request.Username, DateTime.UtcNow);

            return Ok("Login successful");

        }

       

        _logger.LogWarning("Failed login attempt for user: {Username} at {Time}", request.Username, DateTime.UtcNow);

        return Unauthorized("Invalid credentials");

    }

}

 

public class LoginRequest

{

    public string Username { get; set; }

    public string Password { get; set; }

}

Step 2: View Logs

If you attempt a login, the logs will show:

[Information] Login attempt for user: admin at 2024-03-18T12:00:00Z

[Information] Successful login for user: admin at 2024-03-18T12:00:01Z

[Warning] Failed login attempt for user: hacker at 2024-03-18T12:05:00Z

Advanced Features

1. Logging to a Database

To log to a database like SQL Server, install:

Install-Package Serilog.Sinks.MSSqlServer

Modify Program.cs:

.WriteTo.MSSqlServer(

    connectionString: "YourConnectionString",

    sinkOptions: new Serilog.Sinks.MSSqlServer.MSSqlServerSinkOptions { TableName = "Logs" }

)

2. Logging Enrichment

To enrich logs with user context:

Log.Logger = new LoggerConfiguration()

    .Enrich.WithProperty("Environment", "Production")

    .Enrich.WithThreadId()

    .CreateLogger();

3. Serilog Middleware for Request Logging

Enable request logging in Program.cs:

app.UseSerilogRequestLogging();

This will automatically log HTTP requests and responses.

Conclusion

Serilog provides a powerful, structured logging experience for .NET Core applications. By following this guide, you can set up and customize logging to meet your application's needs, ensuring better monitoring, debugging, and performance analysis. The real-time example of user login logging showcases how Serilog can be used in real-world scenarios to track authentication attempts effectively.