🧰 Logging with Serilog in .NET – A Step-by-Step Dev Tutorial

---

Published on: June 11, 2025

Category: Tutorial Tuesday

Tags: Serilog, ASP.NET Core, Logging, Middleware, .NET Core, Dev Tutorial, .NET Dev Corner, Application Insights

---

📘 What is Serilog?

Serilog is a structured logging library for .NET that lets you write logs to multiple outputs (called sinks) in a clean, readable format. It’s ideal for production-grade applications and supports powerful features like filtering, enrichers, and asynchronous logging.

---

⚙️ Step 1: Install Required Packages

Use the following NuGet packages to integrate Serilog in an ASP.NET Core project:

dotnet add package Serilog.AspNetCore
dotnet add package Serilog.Sinks.Console
dotnet add package Serilog.Sinks.File

---

🛠 Step 2: Configure Serilog in Program.cs

using Serilog;

Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.Console()
    .WriteTo.File("logs/log.txt", rollingInterval: RollingInterval.Day)
    .CreateLogger();

var builder = WebApplication.CreateBuilder(args);

// Use Serilog
builder.Host.UseSerilog();

var app = builder.Build();
app.Run();

📝 This config writes logs to both the console and a rolling file.

---

🧪 Step 3: Test Logging

Add this line in any controller or middleware:

Log.Information("This is a test log at {Time}", DateTime.Now);

You’ll see structured output like:

[12:42:30 INF] This is a test log at 6/10/2025 12:42:30 PM

---

🧩 Step 4: Add Enrichers (Optional)

To enrich logs with extra context like thread or process ID:

dotnet add package Serilog.Enrichers.Thread
dotnet add package Serilog.Enrichers.Process

Log.Logger = new LoggerConfiguration()
    .Enrich.WithThreadId()
    .Enrich.WithProcessId()
    .WriteTo.Console()
    .CreateLogger();
    

---

🚀 Bonus: Send Logs to Application Insights or Seq

Use additional sinks for cloud monitoring:

dotnet add package Serilog.Sinks.ApplicationInsights
dotnet add package Serilog.Sinks.Seq

Then configure accordingly for scalable observability.

---

🔍 Why Use Serilog?

Feature	Benefit
Structured logs	Queryable in tools like Seq, ELK
Multi-sinks	Write to console, files, DBs, or cloud
Enrichers	Add custom properties (e.g., request ID)
Performance	Asynchronous support for non-blocking logs

---

💡 Final Thoughts

If you’re not logging, you’re debugging blind. Serilog makes logging simple, powerful, and production-ready for .NET developers.

Start with console and file sinks. Then scale to cloud tools as your app grows.

---

📬 Stay Connected

• 🔗 Blog: www.ajaygangwar.com
• 💼 LinkedIn: Ajay Gangwar
• 📧 Email: seajaygangwar@gmail.com