Change the processing type from int to float in kube_horizontalpodautoscaler_spec_target_metric

[whitebear009]

What this PR does / why we need it:
Since the kube_horizontalpodautoscaler_spec_target_metric metric currently uses the AsInt64() function when processing data, if there is a float type metric between 0 and 1, it will be filtered and will not be displayed.
How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality)

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1594

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[whitebear009]

/assign @fpetkovski
Please review. Thanks.

[fpetkovski]

I assume modifying the slice does not change the behavior because the length of both v and ok is the same. Is that correct?

[whitebear009]

Yes. Because I removed ok during the coding process and forgot to change it back.

I think it's better to use ok here. It has been changed back now.

[fpetkovski]

Could we also add a test case when Value is a float?

[whitebear009]

Test cases have been updated.

[whitebear009]

A new commit has been submitted. Please check again, thanks. @fpetkovski

[fpetkovski]

Since we are now always storing true in ok, do we still need the ok variable? Can we try removing it to see if the tests break?

[whitebear009]

Good idea! The ok variable seems useless. But removing it directly would break the unit test, since we set the length of the v to a constant, it would show the extra zeros (the default value).

Although I can judge whether the value of v[i] is zero (HPA target metric should be required to be greater than 0) to decide whether to display the corresponding metric, but I think this way is not very good.
So Could I change the type of v to the map type, and finally displayed the metric that exists in the map?

[whitebear009]

I have push a new commit. How do you think?

[fpetkovski]

I think a map could work, but it might also create a flaky test. Iterating over a map does not guarantee that the order of the keys will always be the same. Can this lead to metrics being serialized in a different order each time a test is run? Could you run the tests with -count=100?

[whitebear009]

I tried running it with -count=100 and it passed the test.
Because the compareOutput function used in the unit test calls the sortByLine function, it will sort the metric set.

func compareOutput(expected, actual string) error {
	entities := []string{expected, actual}
	// Align wanted and actual
	for i := 0; i < len(entities); i++ {
		for _, f := range []func(string) string{removeUnusedWhitespace, sortLabels, sortByLine} {
			entities[i] = f(entities[i])
		}
	}
	if diff := cmp.Diff(entities[0], entities[1]); diff != "" {
		return errors.Errorf("(-want, +got):\n%s", diff)
	}
	return nil
}
func sortByLine(s string) string {
	split := strings.Split(s, "\n")
	sort.Strings(split)
	return strings.Join(split, "\n")
}

[fpetkovski]

Perfect!

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fpetkovski, whitebear009

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