In Chapter 6: Node Groups (Blue & Green), we configured the worker nodes—the production lines of our EKS Cluster—using the Blue-Green deployment strategy. These Node Groups provide the compute capacity where your containerized applications run and scale.

Now that your applications are running inside the cluster, the next critical question is: How do users actually access them?

Applications don’t exist in isolation—they need to be reachable by internal systems, external clients, or end users over the internet. This is where ingress and traffic management come into play.

In this chapter, we’ll explore the AWS Load Balancer Controller, which serves as the Traffic Director for your Kubernetes workloads. It dynamically provisions AWS-managed load balancers and ensures that user requests are intelligently and securely routed to the right application endpoints running within your EKS cluster.

What Problem Are We Solving?

Imagine you've just launched a fully functioning online store—your application—running smoothly inside your EKS "factory" on the production lines (Node Groups). However, there’s a problem: while everything is operational inside, there’s no public entrance. External users don’t know how to reach your application.

To make your application accessible to users, you need a solution that provides:

• A Public Entry Point

  A recognizable domain (e.g., mystore.com) that users can use to reach your application from the internet.

• Traffic Management

  A system that intelligently routes incoming requests to the correct application service—especially important in microservices architectures with multiple endpoints or teams.

• Scalability

  The ability to handle fluctuating demand—from a handful of users to millions—without becoming a bottleneck or point of failure.

• Dynamic Adaptability

  The ability to automatically reflect infrastructure changes (e.g., Blue-Green node switches or service updates) without requiring manual reconfiguration.

Setting up and managing AWS Load Balancers manually for each application, especially in a dynamic Kubernetes environment, is time-consuming and error-prone. That’s where the AWS Load Balancer Controller comes in.

What Is the AWS Load Balancer Controller?

The AWS Load Balancer Controller is a Kubernetes-native controller that automatically provisions and manages Elastic Load Balancers (ELBs) in AWS based on Kubernetes Ingress and Service resources.

Think of it as your intelligent, automated traffic director. It ensures:

• Public endpoints (ALBs or NLBs) are created when needed
• Traffic is routed to the right application—regardless of which node group it's running on
• Load balancer configurations stay in sync with changes to your Kubernetes services

With this controller in place, your EKS cluster gains automated, scalable, and resilient ingress capability, ensuring users can always reach your applications with minimal effort and maximum reliability.