Fix max-pods-calculator to consider only network card 0

[Pavani-Panakanti]

Issue #, if available: Customer issue

Description of changes:
CNI only works with network card 0 for pods creation. In max-pods-calculator we are taking interfaces from all network cards which is resulting in wrong values for instances with multiple network cards. This is causing issues to cx who are using this script to generate max pod values.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Testing Done

Ran the script across all instance types here https://raw.githubusercontent.com/aws/amazon-vpc-cni-k8s/master/misc/eni-max-pods.txt and verified max pods values from the above file

[orsenthil]

LGTM

[orsenthil]

@cartermckinnon - please review and merge this.

[cartermckinnon]

LGTM, thanks for the fix @Pavani-Panakanti 🙏🏻

[miguellongo]

Hello guys.

I'm looking into new AMIs where errors about pod density happens.

When I use this AMI (ami-060a6e3365dc94a3c), I saw this pull request into max-pods-calculator and I dont got more problems with CNI. Using the latest AMI, I can't see this pull request and I have problems with density and CNI again.

Is this problem on max-pods-calculator scripts or other config into EKS?

Thanks guys.

[mattcjo]

Hey @miguellongo ,

I talked with the Karpenter team on this issue, and it sounds like it's a bug on their end. The Karpenter team is targeting next week with a patch that should fix the problem. I will let you know when it's been completed so you can verify.