Introduction

When designing scalable and resilient web applications, one critical component is how you route and manage traffic to your application services. The use of a load balancer helps distribute incoming traffic across multiple servers, ensuring no single server becomes overwhelmed. Meanwhile, an Ingress controller often facilitates managing the access to internal Kubernetes services, providing a user-friendly way to handle HTTP and HTTPS requests. In this article, we dive deep into the differences between using NGINX as a standalone load balancer versus as an Ingress controller within a Kubernetes cluster.

NGINX as a Load Balancer

Overview

NGINX is a powerful and high-performance web server that can be configured to serve as a load balancer. As a load balancer, NGINX distributes incoming network or application traffic across multiple servers, ensuring resource optimization, enhanced resilience, and increased availability.

Technical Explanation

• Configuration: NGINX load balancer configuration involves setting up `upstream` blocks in the configuration file, specifying the server group you'd like to balance the load across.
• Load Balancing Algorithms: NGINX supports different algorithms for distributing traffic, such as:
  • Round Robin: Distributes requests evenly across the servers.
  • Least Connections: Sends requests to the server with the least number of active connections.
  • IP Hash: Directs requests from the same client to the same server.
• SSL/TLS Termination: NGINX can terminate SSL/TLS connections, decrypting incoming requests before passing them to back-end services. This helps reduce the computation burden on the back-end servers.
• Health Checks: NGINX performs health checks on servers in the `upstream` block, directing traffic only to servers that are running smoothly.

Example Configuration

• Ingress Resource: In Kubernetes, the `Ingress` resource defines how services are exposed. It abstracts the routing logic, allowing developers to manage accesses using HTTP routing rules.
• Annotations and Custom Resources: NGINX Ingress controller can be customized using annotations in the Ingress resources or custom resource definitions (CRDs), offering control over behavior like path-based routing, sticky sessions, and SSL termination.
• Load Balancing: Functions similarly to a traditional NGINX load balancer but tailored to work seamlessly with Kubernetes services.
• SSL/TLS Management: Natively supports SSL/TLS configuration through Kubernetes secrets, easing the management process and allowing automatic certificate management with tools like cert-manager.
  • host: example.com
    • path: /foo