LoadBalancers

Updated May 26, 2022 ·

Overview

Amazon EKS supports three types of load balancers:

Load Balancer	Service Type
Classic Load Balancer	None
Network Load Balancer	LoadBalancer
Application Load Balancer	Ingress Controller

For more information, please see Type LoadBalancer

Annotations

Load balancer configuration is controlled by annotations in Kubernetes manifests.

• Labels: Used to identify and select objects.
• Annotations: Attach metadata without affecting object selection.

For more information, please see Annotations in Kubernetes.

AWS Load Balancer Controller

The AWS Load Balancer Controller manages Elastic Load Balancers for Kubernetes:

• Creates ALB for Ingress resources.
• Creates NLB for services of type LoadBalancer.
• Does not support Classic Load Balancers.

NOTE

Note that it doesn't create AWS Classic Load Balancers. It is recommended to use version 2.4.3 or above if your cluster is version 1.19 and above.

Service annotations are different when using the AWS Load Balancer Controller than they are when using the AWS cloud provider load balancer controller.

To tag load balancers during creation, use this annotation:

service.beta.kubernetes.io/aws-load-balancer-additional-resource-tags 

For more information, please see the links below:

• AWS Load Balancer Controller

• AWS Load Balancer Controller Github page

Classic LoadBalancer

By default, EKS creates a Classic Load Balancer for services of type LoadBalancer. To use a different type, add annotations in the manifest.

• Limited to basic Layer 4 load balancing.
• Lacks advances path-based routing or host-based routing.

Network LoadBalancer

An AWS Network Load Balancer can load balance network traffic to pods deployed to Amazon EC2 IP with either targets.

• Instance targets for EC2 Pods.
• IP targets for Fargate Pods.

Instance Targets

Use the AWS Load Balancer Controller to create Network Load Balancers with instance targets.

• To deploy an NLB in a private subnet, add these annotations:

  service.beta.kubernetes.io/aws-load-balancer-type: "external"
  service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "instance"

• For an NLB in a public subnet (e.g., to load balance to EC2 nodes):

  service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"

IP Targets

To create an NLB using IP targets for Pods:

• Add these annotations to your manifest:

  service.beta.kubernetes.io/aws-load-balancer-type: "external"
  service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "ip"

• For public-facing NLBs (Fargate workloads must remain private):

  service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"

• To assign Elastic IPs, add:

  service.beta.kubernetes.io/aws-load-balancer-eip-allocations: eipalloc-xxxxxx,eipalloc-yyyyyy

For more information, please see Network load balancing on Amazon EKS.

Application Load Balancer

For Layer 7 traffic, use Kubernetes Ingress to create ALBs:

• Works with Pods on nodes or Fargate.
• Supports public or private subnets.

To tell the AWS LoadBalancer Controller to create an ALB and its supporting resources when a Kubernetes Ingress is created, add this annotation to the manifest:

annotations:
    kubernetes.io/ingress.class: alb 

To loadbalance on IPv6 pods deployed on IP targets (instance targets not allowed):

alb.ingress.kubernetes.io/ip-address-type: dualstack 

The AWS Load Balancer Controller supports the following traffic modes:

• Instance mode: Routes traffic to NodePort services, then Pods.
• IP mode: Directly routes ALB traffic to Pods.

For more information, please see the links below:

• Application load balancing on Amazon EKS.

• Kubernetes Ingress.