I'm facing an issue with my EKS cluster regarding cross-VPC connectivity through a Transit Gateway.
Initial EKS Configuration: I have an EKS cluster originally set up with two subnets in a VPC (let's call it EKS-VPC), and everything was functioning correctly with two nodes in these subnets.
Network Expansion: Due to expansion needs, I added a secondary CIDR block(lessons learned for not using larger cidr) to the EKS-VPC and created a third subnet from this new range. Node Group Addition: I then created a new node group in the EKS cluster and successfully launched a third node in this new subnet. Pods are being scheduled on this node without issues.
Cross-VPC Setup: My setup includes another VPC (let's call it Test-VPC), which is connected to the EKS-VPC via a Transit Gateway.
The Core Issue: From a test machine within the Test-VPC, I can ping the first two nodes in the EKS-VPC without any issues.
However, I'm unable to get a response when trying to ping the third node, which resides in the newly created subnet.
I checked the portal and on networking only two subnets are registered which are the ones created during the initial setup. I am not able to see or add third subnet from there. So I assume this is the reason for third node not being able to get a response back from the network outside of the vpc.
How can I ensure that the third subnet, created from the secondary CIDR block, is properly integrated into the EKS cluster's networking, especially for cross-VPC communication through the Transit Gateway without tearing down and rebuilding the whole cluster? Are there specific configurations or adjustments needed in the EKS or Transit Gateway setup to recognize and facilitate connectivity to this new subnet?
Thank you for your time and help!