Feature: Remove usage of eksctl

[bryantbiggs]

Summary

eksctl already provides support for upgrading the control plane of a cluster created by its CLI https://eksctl.io/usage/cluster-upgrade/

This is mainly done just to keep the generated CloudFormation in-sync with any changes. It currently does not support upgrading any components of the data plane; these are handled in the same way that upgrades are handled here. Therefore, the data plane and addon upgrade logic and be used on clusters created by eksctl and a separate, unique process does not need to exists

Why is this needed?

If users are using eksctl today, they should continue using it to perform upgrades of the control plane as per eksctl. Since eksctl does not support upgrading any components of the data plane, we can still support that process with eksupgrade

Which area does this relate to?

Automation

Solution

• We can keep this wrapped call to eksctl or we can replace it and instruct users to upgrade the control plane first.

• Functionality will need to be added to support performing data plane only upgrades. This process will inspect the control plane version and update the data plane components to match (update nodegroups, Fargate profiles, addon default versions, etc.). This is useful both for the eksctl scenario as well as for the guidance provided to users to ensure the data plane components are aligned with the control plane prior to upgrading. Therefore, users can also use this functionality to align their data plane with the control plane prior to performing an upgrade

[bryantbiggs]

I guess this is more of a feature rather than maintenance (in hindsight)

[mbeacom]

The eksctl functionality is totally inaccessible to the enduser right now:

eks-cluster-upgrade/eksupgrade/starter.py

Lines 160 to 161 in 85a6093

	if args.eksctl:
	sys.exit("updating using EKSCTL is still under testing will be launched soon")

We may as well remove it and if desired, re-add something in the new interface.