docs: Remove the word "necessary" from optional fields

[jonathan-innis]

Fixes #N/A

Description

This updates the docs to clarify that only one of spec.role and spec.instanceProfile is needed since the previous wording might have been confusing with respect to this.

How was this change tested?

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[coveralls]

Pull Request Test Coverage Report for Build 7894271127

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.514%

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Totals
Change from base Build 7893386178:	0.0%
Covered Lines:	5016
Relevant Lines:	6079

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💛 - Coveralls

[andrewhibbert]

Would it be possible to clarify this bit:

For private clusters that do not have access to the public internet, using spec.instanceProfile is required. spec.role cannot be used since Karpenter needs to access IAM endpoints to manage a generated instance profile. IAM doesn’t support private endpoints to enable accessing the service without going to the public internet.

If you're in a private cluster with access to internet via NAT gateway, you'll reach IAM over the public internet, so it would be good to know the implications of this in terms of cost, does it contact the endpoint just once to generate the profile or is it a repetitive process?

[jonathan-innis]

good to know the implications of this in terms of cost

I'm not sure what you mean in terms of cost. IAM entities don't incur additional cost so I don't think that should be a concern there. In terms of the actual behavior of Karpenter, it is a continuous reconciliation so if you were to delete the instance profile accidentally or remove the role, Karpenter would add it back. You need constant access to IAM if you are using the spec.role field.

[andrewhibbert]

Possibly I'm missing something, if using an instance profile, it wouldn't go over public internet to IAM, whereas with a role it would and do so continuously to reconcile? Sounds like it would cost more