Kubernetes loadbalancer service vs cloud loadbalancer

Question

In Kubernetes configuration, for external service component we use:

type: LoadBalancer

If we have k8s cluster running inside a cloud provider like AWS, which provides it own loadbalancer, how does all this work then? Do we need to configure so that one of these loadbalancers is not active?

Answer 1

AWS now takes over the open source project: https://kubernetes-sigs.github.io/aws-load-balancer-controller

It works with EKS(easiest) clusters as well as non-EKS clusters (need to install aws vpc cni etc to make IP target mode work, which is required if you have a peered VPC environment.)

This is the official/native solution of managing AWS LB(aka ELBv2) resources(App ELB, Network ELB) using K8s. Kubernetes in-tree controller always reconciles Service object with type: LoadBalancer

Once configured correctly, AWS LB controller will manage the following 2 types of LBs:

1. Application LB, via Kubernetes Ingress object. It operates on L7 and provides features related to HTTP
2. Network LB, via Kubernetes Service object with correct annotations . It operates on L4 and provides less features but claimed MUCH higher throughput.

To my knowledge, this works best when used with external-dns together -- it automatically updates your Route53 record with your LB A records thus makes the whole service discovery solution k8s-y.

Also in general, should prevent usage of classic ELB, as it's marked as deprecated by AWS.