Amazon EKS supports the three types of Loadbalancers:
| Loadbalancer | Service type B |
|---|---|
| Classic Loadbalancer | None |
| Network Loadbalancer | LoadBalancer |
| Application Loadbalancer | Ingress Controller |
To learn more about loadbalancers, check out Type LoadBalancer
The configuration of the load balancer is controlled by annotations that are added to the manifest files.
We can use either labels or annotations to attach metadata to Kubernetes objects.
Labels can be used to select objects and to find collections of objects that satisfy certain conditions.
Annotations, on the other hand, are not used to identify and select objects. The metadata in an annotation can be small or large, structured or unstructured, and can include characters not permitted by labels.
To learn more, check out Annotations in Kubernetes.
The AWS Load Balancer Controller manages AWS Elastic Load Balancers for a Kubernetes cluster. The controller provisions the following resources:
An AWS Application Load Balancer (ALB) when you create a Kubernetes Ingress.
An AWS Network Load Balancer (NLB) when you create a Kubernetes service of type LoadBalancer
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 add tags to the load balancer when or after it’s created, add the following annotation in your service specification:
service.beta.kubernetes.io/aws-load-balancer-additional-resource-tags
To learn more AWS Load Balancer Controller, check out the links below:
By default, EKS will create a classic loadbalancers when you create a Kubernetes Service of type LoadBalancer. We can change it by adding the annotations in the manifest file.
An AWS Network Load Balancer can load balance network traffic to pods deployed to Amazon EC2 IP with either targets.
To loadbalance traffic across Pods deployed in EC2 nodes, use instance targets.
To loadbalance traffic across Pods deployed in Fargate, use IP targets.
It is recommended to use the AWS Load Balancer Controller to creates the Network Load Balancers with instance targets.
To deploy a Network Load Balancer to a private subnet, add the following annotation to your manifest and deploy the services:
service.beta.kubernetes.io/aws-load-balancer-type: "external"
service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "instance"
The external value tells the the AWS Load Balancer Controller (rather than the AWS cloud provider load balancer controller) to create the Network Load Balancer.
If you want to create an Network Load Balancer in a public subnet to load balance to Amazon EC2 nodes, add this annotation:
service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"
To create an NLB that uses IP targets for the Pods, ad the following annotation to your manifest and deploy the service:
service.beta.kubernetes.io/aws-load-balancer-type: "external"
service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "ip"
The external value tells the the AWS Load Balancer Controller (rather than the AWS cloud provider load balancer controller) to create the Network Load Balancer.
If you want to create a Network Load Balancer in a public subnet to load balance to Amazon EC2 nodes (Fargate can only be private), add these annotation:
service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"
To assign Elastic IP addresses to NLB, add this to the annotations:
service.beta.kubernetes.io/aws-load-balancer-eip-allocations: eipalloc-xxxxxxxxxxxxxxxxx,eipalloc-yyyyyyyyyyyyyyyyy
To learn more about NLBs, check out Network load balancing on Amazon EKS.
To load balance application traffic at L7, we deploy a Kubernetes ingress, which provisions an AWS Application Load Balancer.
To tell the AWS LoadBalancer Controller to create an ALB and its supporting resources when a Kubernetes Ingress is created, we need to add this annotation to our 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:
To learn more, check out Application load balancing on Amazon EKS.
Details about the open source Ingress can be found in the Kubernetes documentation.