fix(kube_pod_tolerations): deduplicate tolerations before creating metric

[RiRa12621]

What this PR does / why we need it:
duplicate metrics currently create warnings in the logs of prometheus. Tolerations can be duplicated and kube-api doesn't want to change that behavior, hence we have to deduplicate here

How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality)
does not change cardinality

Which issue(s) this PR fixes
Fixes #2390

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[RiRa12621]

/assign @dgrisonnet

[mrueg]

The solution looks good to me.
Any thoughts on using slices.Sort + slices.Compact similar to #2502 ? This might be simpler than building a separate function for it.

[CatherineF-dev]

The solution looks good to me. Any thoughts on using slices.Sort + slices.Compact similar to #2502 ? This might be simpler than building a separate function for it.

+1

[RiRa12621]

Sure, I'll get that changed tomorrow

[rgarcia89]

@RiRa12621 are you still working on that PR?

[RiRa12621]

Planning to, was just overly busy at day job

[remram44]

The solution looks good to me. Any thoughts on using slices.Sort + slices.Compact similar to #2502 ? This might be simpler than building a separate function for it.

I don't know if it's easier. To use slices.Sort rather than a map, you need Ordered not just Comparable, and v1.Toleration is not Ordered. So you would need to provide a comparison function which would be quite long (you need to sort by key+operator+value+effect).

func compareTolerations(a, b v1.Toleration) int {
	return cmp.Or(
		strings.Compare(a.Key, b.Key),
		strings.Compare(string(a.Operator), string(b.Operator)),
		strings.Compare(a.Value, b.Value),
		strings.Compare(string(a.Effect), string(b.Effect)),
	)
}

// ...

var uniqueTolerations []v1.Toleration
uniqueTolerations = append(uniqueTolerations, p.Spec.Tolerations...)
slices.SortFunc(uniqueTolerations, compareTolerations)
uniqueTolerations = slices.CompactFunc(uniqueTolerations, func(a, b v1.Toleration) bool {
	return compareTolerations(a, b) == 0
})

[mrueg]

Good point, I think this is good to go then.

Thanks for your contribution @RiRa12621

/lgtm

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mrueg, RiRa12621

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