ASP.NET Core  

Centralized Logging & Monitoring in ASP.NET Core using Serilog and Elastic Stack (ELK)

Introduction

In modern enterprise applications, logs are your first line of defense against production issues.
When your system runs across multiple APIs, microservices, and background jobs, collecting and analyzing logs becomes a challenge.

That’s where Centralized Logging comes in — a single place to collect, search, and analyze logs in real time.

In this article, you’ll learn how to build a Centralized Logging and Monitoring system using:

  • Serilog for structured logging in ASP.NET Core

  • Elastic Stack (ELK) — Elasticsearch, Logstash, and Kibana — for log aggregation, processing, and visualization

Why Centralized Logging?

Let’s say you’re running a web application with multiple APIs.

When a user reports,

“Something failed when placing an order,”

you might have to check multiple log files across servers to find what went wrong.

Centralized logging solves that by:

  • Storing all logs in one place

  • Making logs searchable and filterable

  • Offering real-time dashboards and alerts

  • Enabling pattern detection for performance or security issues

Architecture Overview

Here’s how everything connects:

  
    ASP.NET Core App
     │
     ▼
 [Serilog]
     │
     ▼
 [Logstash]
     │
     ▼
 [Elasticsearch]
     │
     ▼
 [Kibana Dashboard]

Explanation

  1. ASP.NET Core app writes structured logs via Serilog .

  2. Logs are sent to Logstash , which parses and processes them.

  3. Elasticsearch stores and indexes logs efficiently.

  4. Kibana visualizes the logs in dashboards and reports.

Step 1: Setting Up ELK Stack

Option 1: Using Docker (Recommended for Local Setup)

Create a docker-compose.yml file:

  
    version: '3.3'
services:
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:8.10.0
    environment:
      - discovery.type=single-node
      - ES_JAVA_OPTS=-Xms1g -Xmx1g
    ports:
      - "9200:9200"

  logstash:
    image: docker.elastic.co/logstash/logstash:8.10.0
    ports:
      - "5044:5044"
    volumes:
      - ./logstash.conf:/usr/share/logstash/pipeline/logstash.conf
    depends_on:
      - elasticsearch

  kibana:
    image: docker.elastic.co/kibana/kibana:8.10.0
    ports:
      - "5601:5601"
    depends_on:
      - elasticsearch

Logstash Configuration Example ( logstash.conf )

  
    input {
  tcp {
    port => 5044
    codec => json_lines
  }
}

output {
  elasticsearch {
    hosts => ["http://elasticsearch:9200"]
    index => "aspnetcore-logs-%{+YYYY.MM.dd}"
  }
}

Step 2: Add Serilog to an ASP.NET Core Project

Install NuGet packages

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

Step 3: Configure Serilog in Program.cs

  
    using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Configure Serilog
Log.Logger = new LoggerConfiguration()
    .Enrich.FromLogContext()
    .WriteTo.Console()
    .WriteTo.File("Logs/app-.log", rollingInterval: RollingInterval.Day)
    .WriteTo.TCPSink("localhost", 5044) // Send to Logstash
    .CreateLogger();

builder.Host.UseSerilog();

builder.Services.AddControllers();
var app = builder.Build();

app.MapControllers();
app.Run();

What this does

  • Logs are written to cthe onsole and file locally.

  • At the same time, logs are sent to Logstash over TCP.

Step 4: Create a Sample Controller

Log Example

  
    using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

[ApiController]
[Route("api/[controller]")]
public class OrderController : ControllerBase
{
    private readonly ILogger<OrderController> _logger;

    public OrderController(ILogger<OrderController> logger)
    {
        _logger = logger;
    }

    [HttpPost("place")]
    public IActionResult PlaceOrder()
    {
        _logger.LogInformation("Order placed successfully at {time}", DateTime.UtcNow);
        return Ok("Order created");
    }

    [HttpGet("error")]
    public IActionResult ThrowError()
    {
        try
        {
            throw new Exception("Test exception in order processing");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Order processing failed");
            return StatusCode(500, "Error");
        }
    }
}

Step 5: Verify Logs in Kibana

Once your ASP.NET Core app starts sending logs, open Kibana :

👉 http://localhost:5601

Create a new index pattern — aspnetcore-logs-*

You’ll now see logs from your .NET app appear live in Kibana’s “Discover” tab.
You can also:

  • Filter by log level ( Information , Error , Warning )

  • Group by controller or service name

  • Create dashboards showing error frequency, API response time, and more.

Step 6: Adding More Context with Enrichment

Serilog lets you enrich logs with contextual data such as:

  • Current user

  • Request ID

  • Correlation ID

  • Environment (Dev, QA, Prod)

Example

  
    Log.Logger = new LoggerConfiguration()
    .Enrich.WithProperty("Application", "OrderService")
    .Enrich.WithProperty("Environment", builder.Environment.EnvironmentName)
    .Enrich.FromLogContext()
    .WriteTo.Console()
    .WriteTo.TCPSink("localhost", 5044)
    .CreateLogger();

This helps you filter and analyze logs by app or environment directly in Kibana.

Step 7: Visualizing Metrics & Alerts in Kibana

Kibana isn’t just for log browsing. You can:

  • Create error trend charts

  • Visualize API call patterns

  • Set email or Slack alerts for high error rates

  • Correlate logs with performance metrics (e.g., CPU or memory usage)

This transforms your logs into an observability system , not just error tracking.

Step 8: Security & Maintenance Tips

  • ✅ Always secure your ELK endpoints using authentication and SSL.

  • ✅ Use log rotation to prevent disk space issues.

  • ✅ Avoid logging sensitive data (passwords, tokens).

  • ✅ Use separate indices for different environments.

Real-World Use Cases

  • Multi-tenant SaaS Platforms: Monitor logs per tenant or region.

  • E-Commerce Systems: Trace transaction failures in real time.

  • Microservice Architectures: Aggregate logs from multiple services into one dashboard.

  • DevOps Teams: Use log trends for root cause analysis and uptime metrics.

Flow Diagram – Serilog + ELK Stack Integration

  
    +------------------------+
|   ASP.NET Core App     |
| (Serilog Integration)  |
+-----------+------------+
            |
            v
+------------------------+
|     Logstash (Parser)  |
+-----------+------------+
            |
            v
+------------------------+
|  Elasticsearch (Index) |
+-----------+------------+
            |
            v
+------------------------+
|     Kibana Dashboard   |
| (Search, Visualize)    |
+------------------------+

Conclusion

Centralized logging with Serilog and ELK Stack brings structure, visibility, and control to your ASP.NET Core applications.
You no longer need to jump between servers or check log files manually — everything is in one place, searchable, visual, and intelligent.

If you’re running a large enterprise or cloud-based system, setting up this pipeline is one of the best investments you can make for reliability and operational insight.

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