Stability of NLB DNS Name Provisioned by AWS Load Balancer Controller

[jennproos-twisthink]

Environment
Kubernetes version: 1.32
AWS Load Balancer Controller version: 2.13
Istio Ingress Gateway Helm chart version: 1.25.1
AWS region: us-east-1

Current Setup
We have deployed an Istio Ingress Gateway using the official Helm chart, which creates a Service of type LoadBalancer. We've configured it with the following annotations:

yamlservice.beta.kubernetes.io/aws-load-balancer-nlb-target-type: ip
service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"
service.beta.kubernetes.io/aws-load-balancer-cross-zone-load-balancing-enabled: "true"

This results in the AWS Load Balancer Controller provisioning a Network Load Balancer with its own DNS name. 🎉

External DNS Integration
We're using a custom DNS provider that isn't supported by the External DNS EKS Add-on. Our plan is to create CNAME records for our various hostnames that point to the NLB's DNS name.

Question
How stable is the DNS name assigned to the Network Load Balancer provisioned by the AWS Load Balancer Controller? Specifically:

1. Can we expect this DNS name to remain unchanged as long as the Kubernetes Service object remains unchanged and the cluster stays operational?
2. Are there any scenarios where the AWS Load Balancer Controller might delete and recreate the underlying NLB, resulting in a new DNS name?
3. Are there any best practices or alternative approaches for ensuring DNS name stability when using the AWS Load Balancer Controller with Network Load Balancers?

We want to ensure that once we create CNAME records pointing to this NLB DNS name, we won't need to update them unexpectedly.
Thank you for any insights!

[FernandoMiguel]

1: yes
2: if you delete the ingress, it will be destroyed. I believe you can set the ACK to prevent removal of resources
3: they are static

[jennproos-twisthink]

Thank you for confirming! Appreciate your quick response :)

[zac-nixon]

Hello! These answers are mostly correct. One caveat is that changing the Load Balancer scheme will result in the DNS name being recreated.

https://github.com/kubernetes-sigs/aws-load-balancer-controller/blob/main/pkg/service/model_build_load_balancer.go#L598

So, in your example if you wanted to change to an internal load balancer, the DNS name would be recreated.

[jennproos-twisthink]

That's good to know, thank you!