Logging isn't just about printing errors — it's about observability, traceability, and debugging production issues before they become outages. In this post, let’s explore how to implement enterprise-grade logging using Serilog in .NET — from basic setup to advanced features.
Why Serilog?
Serilog is a structured logging library for .NET that makes your logs queryable, filterable, and machine-readable. It supports:
- Multiple sinks (console, file, Seq, Elasticsearch, etc.)
- Enrichers for contextual data
- Asynchronous logging
- Easy integration with ASP.NET Core
Getting Started
Install the required NuGet packages:
dotnet add package Serilog.AspNetCore
dotnet add package Serilog.Sinks.Console
dotnet add package Serilog.Sinks.File
In Program.cs (for .NET 6+):
using Serilog;
```Log.Logger = new LoggerConfiguration()
.WriteTo.Console()
.WriteTo.File("logs/log-.txt", rollingInterval: RollingInterval.Day)
.Enrich.FromLogContext()
.CreateLogger();
var builder = WebApplication.CreateBuilder(args);
builder.Host.UseSerilog(); // Replace default logging
var app = builder.Build();```
Add Contextual Information
Serilog’s enrichers make your logs more meaningful:
dotnet add package Serilog.Enrichers.Environment
dotnet add package Serilog.Enrichers.Thread
Update configuration:
Log.Logger = new LoggerConfiguration()
.Enrich.WithEnvironmentUserName()
.Enrich.WithThreadId()
.WriteTo.Console()
.CreateLogger();
This adds thread ID, machine name, and user context to every log.
Logging in Action
Use it anywhere in your app:
```public class ProductService
{
private readonly ILogger _logger;
public ProductService(ILogger<ProductService> logger)
{
_logger = logger;
}
public void Process()
{
_logger.LogInformation("Processing started at {Time}", DateTime.UtcNow);
}
}```
Use AppSettings (Optional)
You can configure Serilog in appsettings.json for flexibility:
"Serilog": {
"MinimumLevel": "Information",
"WriteTo": [
{ "Name": "Console" },
{ "Name": "File", "Args": { "path": "logs/app.txt" } }
]
}
And in Program.cs:
builder.Host.UseSerilog((ctx, lc) =>lc.ReadFrom.Configuration(ctx.Configuration));
Sinks You Should Know
- Console/File — Local development & basic diagnostics
- Seq — Beautiful web UI for structured logs
- Elasticsearch — Ideal for large-scale distributed logging
- Application Insights — Works well in Azure environment
Best Practices for Production
- Use asynchronous sinks to avoid blocking threads.
- Avoid logging sensitive info (e.g., passwords, tokens).
- Add correlation IDs for request tracing (via middleware).
- Log levels properly: Use Debug, Info, Warn, Error, Fatal.
- Monitor log size & rotation to prevent disk bloat.
Conclusion
With Serilog, you get powerful, extensible logging out of the box. It gives you structure, performance, and flexibility — everything you need for enterprise-ready applications.
Want to see more on advanced sinks like Elasticsearch + Kibana, or how to build a correlation ID middleware? Drop a comment below!