Try Logging in a .NET API and Visualize Logs in Seq

Learn how to integrate structured logging in a .NET API using Serilog and visualize logs in Seq for efficient debugging and monitoring. Step-by-step guide included.

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Introduction

Logging is an essential part of modern application development, providing visibility into system behavior, debugging, and performance monitoring. However, raw logs can be difficult to analyze, making structured logging a necessity.

Serilog is a powerful logging library for .NET that enables structured logging, while Seq is a real-time log visualization tool that makes it easier to filter, search, and analyze logs.

In this guide, you will learn how to integrate Serilog into a .NET API and send logs to Seq for seamless debugging and monitoring.

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Why Use Serilog and Seq for Logging?

Serilog Features:

• Structured Logging – Logs data in JSON format for easy querying.
• Multiple Sinks – Supports writing logs to files, databases, cloud services, and more.
• Enrichers – Adds contextual information like request IDs, user identities, etc.
• Asynchronous Logging – Improves performance by handling logs in the background.

Seq Benefits:

• Powerful Querying – Search and filter logs using structured queries.
• Live Dashboard – View real-time logs with visual charts.
• Error Tracking – Detect anomalies and troubleshoot issues efficiently.
• Centralized Logging – Aggregate logs from multiple services in one place.

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Setting Up Serilog in a .NET API

Step 1: Install Required Packages

In your .NET API project, install the following NuGet packages:

 dotnet add package Serilog.AspNetCore
 dotnet add package Serilog.Sinks.Seq

Step 2: Configure Serilog in Program.cs

Modify your Program.cs file to configure Serilog and enable logging:

using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Configure Serilog
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .WriteTo.Seq("http://localhost:5341")
    .Enrich.FromLogContext()
    .CreateLogger();

builder.Host.UseSerilog();

var app = builder.Build();

app.UseSerilogRequestLogging();

app.MapGet("/hello", () => {
    Log.Information("Hello API endpoint hit");
    return Results.Ok("Hello, World!");
});

app.Run();

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Running and Visualizing Logs in Seq

Step 1: Install and Start Seq

Download and install Seq from https://datalust.co/seq. Once installed, start the Seq service by running:

 seq.exe run

Seq will be accessible at http://localhost:5341.

Step 2: Run Your .NET API

Start your API project:

 dotnet run

Step 3: Generate Some Logs

Make a request to the API endpoint:

 curl http://localhost:5000/hello

Step 4: View Logs in Seq

Go to http://localhost:5341 in your browser. You should see the log messages appearing in real time.

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Best Practices for Logging in .NET APIs

1. Use Log Levels Wisely – Leverage levels like Debug, Information, Warning, Error, and Fatal for better insights.
2. Enrich Logs – Add request details, user context, and correlation IDs to make logs more meaningful.
3. Avoid Logging Sensitive Data – Ensure logs don’t contain passwords, PII, or confidential information.
4. Enable Log Rotation – Prevent large log files from consuming disk space by setting retention policies.
5. Centralized Logging – Use Seq in production to aggregate logs from multiple microservices.

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FAQs

1. What is the difference between Serilog and Seq?

Serilog is a structured logging library for .NET, while Seq is a log visualization tool that helps analyze logs in real-time.

2. Can I use Seq in a production environment?

Yes, Seq is designed for both development and production use. However, for large-scale applications, consider using cloud-based logging solutions like Azure Monitor, Elasticsearch, or Splunk.

3. How do I filter logs in Seq?

Seq provides a query syntax to filter logs. Example:

@Level = 'Error' and RequestPath like '/api/%'

4. How can I store logs in a database?

Use Serilog sinks like Serilog.Sinks.MSSqlServer to store logs in a SQL database.

5. How do I send logs to a cloud service?

You can configure Serilog to send logs to Azure Application Insights, AWS CloudWatch, or Google Stackdriver using appropriate sinks.

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Conclusion

Logging is a crucial part of software development, and integrating Serilog with Seq provides a powerful, structured approach to debugging and monitoring .NET APIs. By following this guide, you can set up a robust logging system, gain real-time insights, and improve application performance.

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