What happened: We tried to update our cluster to use version 1.26.8-20230919 for the nodes and the newly launched ec2 instances (repeatedly) failed to join the cluster.

What you expected to happen: The new nodes should successfully join the cluster

How to reproduce it (as minimally and precisely as possible): Start a cluster with an older AMI and then update to v1.26.8-20230919 .

Anything else we need to know?:
I have looked into it and here is what I found:

• The node does not start because it fails to pull the pause-image
• In the containerd logs we see messages like: The image 602401143452.dkr.ecr.ap-south-2\nap-south-1\neu-south-1\neu-south-2\nme-central-1\nil-central-1\nca-central-1\neu-central-1\neu-central-2\nus-west-1\nus-west-2\naf-south[...]amazonaws.com/eks/pause:3.5 is not unpacked.
• That image-name does not seem correct to me. Instead of a single region, it contains all the regions, separated by newlines.
• Looking into the git-commits of this repo we find: be7bc10
• In the script (from the commit mentioned above) the variable REGIONS contains a newline separated list of all regions
• The loop in line 469 does not work. Instead of iterating over the regions, it just runs unce, placing the whole (newline separated) list of regions into the region-variable
• This broken region-variable is then used in the next few lines to build the image-names, resulting in broken, un-pullable images.

I think that this broken image-names prevent the node from booting up properly.

Environment:

• AWS Region: eu-west-1
• Instance Type(s): t3a.large
• EKS Platform version (use aws eks describe-cluster --name <name> --query cluster.platformVersion):
• Kubernetes version (use aws eks describe-cluster --name <name> --query cluster.version): eks.6
• AMI Version: v1.26.8-20230919
• Kernel (e.g. uname -a): 5.10.192-183.736.amzn2.x86_64
• Release information (run cat /etc/eks/release on a node):

BASE_AMI_ID="ami-0bac1825e471f5042"
BUILD_TIME="Mon Oct  2 20:39:23 UTC 2023"
BUILD_KERNEL="5.10.192-183.736.amzn2.x86_64"
ARCH="x86_64"