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I have an EKS cluster with worker nodes in private subnet. The worker nodes can access internet via the nat gateway. I have a Route53 hosted zone record routing traffic (alias) to a load balancer.

When I try to access the url (route53 record) from a pod within the EKS cluster, it times out. I tried allowing the worker nodes security group in the inbound rules of the load balancer security group but it does not work. Only thing that works is if I allow the public IP of the nat gateway in the inbound rules of the load balancer security group.

I am sure this setup is very common. My question is, is the solution of allowing the nat gateway public ip in the inbound rules of the LB SG the correct way or is there a better cleaner way to allow the access?

Vishal
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  • How do you setup your pod proxy? with Ingress + Services/Endpoints? or simply expose your deployment? – Binh Nguyen Oct 08 '21 at 15:47
  • The pod service is of type LoadBalancer which creates AWS load balancer and Route53 record is an alias to this load balancer – Vishal Oct 08 '21 at 15:57

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based on what you have described here, it seems like you have a internet facing load balancer and trying to access it from the pod. In this case, the traffic needs to go out to internet(through nat gateway) and come back to the load balancer, that is why it only works when you add the public IP of nat gateway to load balancer's SG. Now, in terms of the solution, it depends on what you are trying to do here:

  • if you only need to consume the service inside the cluster, you can use DNS name created for that service inside the cluster. in this case the traffic will stay inside the cluster. you can read more here
  • if you need to make the service available to other clusters but same VPC, you can use a private load balancer and add the security group of worker nodes to the load balancer SG.
  • if the service needs to be exposed to internet, then your solution works but you have to open the SG of the public load balancer to all public IPs accessing the service.
Reza Nasiri
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