Drift Hash Versioning

[engedaam]

Description

What problem are you trying to solve?

The current implementation of the hashing mechanism that is utilized for drift does not make any consideration when there are updates to the NodePool CRDs during karpenter upgrades. The problem that is present here is that all nodes on a customers cluster will get drifted without any changes to the node configuration, but when upgrading the Karpenter CRDs.

More generally, Karpenter will need guard against the following cases during a karpenter upgrade:

1. NodePool adds a default value to existing fields that are included in hash calculations
2. NodePool field added to the hash calculation with an already-set values
3. NodePool field, with and without defaults values, is removed from the hash calculations

Without safeguards, users that upgrade to new versions of Karpenter with changes to Drift hashing mechanism will see their whole fleet rolled over and recycled.

This would required to support in solving the following issues: #909, #337, #493, and aws/karpenter-provider-aws#5447

How important is this feature to you?
This will need to be implemented before v1

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[engedaam]

This issue has been implemented and will be in the next release