.NET Logging with Serilog and Seq: A Complete Guide

Enhance your .NET application's logging with Serilog and Seq! Learn how to configure, store, and analyze logs efficiently in this step-by-step guide.

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Introduction

Logging is a critical part of any .NET application, helping developers track errors, analyze performance, and gain insights into system behavior. While .NET provides built-in logging capabilities, Serilog takes it to the next level with structured logging. Pairing Serilog with Seq, a real-time event log analysis platform, provides an efficient and scalable way to monitor logs.

In this guide, we'll explore how to set up Serilog with Seq, configure it in a .NET application, and use it for advanced logging scenarios.

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Why Use Serilog and Seq?

Serilog Benefits:

• Structured Logging: Logs are stored as structured data, making them easier to query and analyze.
• Flexible Sinks: Supports multiple storage options (console, files, databases, cloud, and Seq).
• Rich Context: Enables contextual logging with properties.
• Asynchronous Logging: Reduces application performance impact.

Seq Benefits:

• Real-time log search: Filter and analyze logs instantly.
• Powerful querying: SQL-like syntax for log searches.
• Dashboards & Alerts: Visualize log data and set up alerts for issues.
• Seamless Integration: Works effortlessly with Serilog.

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Setting Up Serilog in .NET

Step 1: Install Required Packages

Run the following NuGet command in your .NET project:

Install-Package Serilog.AspNetCore
Install-Package Serilog.Sinks.Console
Install-Package Serilog.Sinks.File
Install-Package Serilog.Sinks.Seq

Step 2: Configure Serilog in Program.cs (Minimal API/.NET 6+)

using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Configure Serilog
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .WriteTo.File("logs/log-.txt", rollingInterval: RollingInterval.Day)
    .WriteTo.Seq("http://localhost:5341")
    .Enrich.FromLogContext()
    .CreateLogger();

builder.Host.UseSerilog();

var app = builder.Build();

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

app.Run();

Step 3: Run Your Application

Start your .NET app, and you’ll see logs appearing in the console and the log files.

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Setting Up Seq for Log Analysis

Step 1: Install Seq

• Download and install Seq from https://getseq.net.
• Start the Seq server (http://localhost:5341 by default).

Step 2: Configure Serilog to Send Logs to Seq

If you followed the previous configuration, your logs are already being sent to Seq. Open the Seq UI, and you’ll see your logs in real time.

Step 3: Query Logs in Seq

Use simple queries like:

SELECT * FROM logs WHERE Level = 'Error'

Or filter by properties:

SELECT * FROM logs WHERE Properties.UserId = '1234'

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Advanced Logging Scenarios

Logging with Context

Log.Information("User {UserId} logged in", userId);

This stores UserId as a structured property, making it searchable in Seq.

Logging Exceptions

try
{
    throw new Exception("Something went wrong!");
}
catch (Exception ex)
{
    Log.Error(ex, "An error occurred");
}

Logging Performance Metrics

Use Serilog’s Timers to measure execution time:

var stopwatch = Stopwatch.StartNew();
// Some process
stopwatch.Stop();
Log.Information("Process took {ElapsedMilliseconds} ms", stopwatch.ElapsedMilliseconds);

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FAQ

1. How does Serilog compare to built-in .NET logging?

Serilog offers structured logging, making it superior to the default logging framework in terms of querying, storage flexibility, and contextual logging.

2. Can I use Seq in production?

Yes! Seq is production-ready and supports high-scale applications, but you may need a licensed version for large workloads.

3. How do I store logs in a database?

Use Serilog.Sinks.MSSqlServer to store logs in SQL Server:

Install-Package Serilog.Sinks.MSSqlServer

4. How do I integrate Serilog with cloud logging platforms?

You can use sinks like Serilog.Sinks.AzureAnalytics or Serilog.Sinks.AmazonCloudWatch.

5. What are the best practices for Serilog logging?

• Use structured logging instead of plain text.
• Store logs in multiple sinks (e.g., file, database, Seq).
• Enrich logs with contextual data.
• Set up log levels appropriately (Debug, Info, Warning, Error, Fatal).

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Conclusion

Serilog and Seq provide a powerful logging solution for .NET applications, offering structured logs, real-time search, and seamless integration. By implementing Serilog correctly, you can debug faster, monitor system health, and improve application performance.

Start using Serilog with Seq today and make your .NET logging smarter and more efficient! 🚀

💡 Next Steps:

• Try logging in a .NET API and visualize logs in Seq.
• Explore cloud-based logging options with Serilog sinks.
• Optimize logging performance with async logging strategies.

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