Fix:flaky CA E2E test "shouldn't trigger additional scale-ups"

[yashrajshuklaaa]

Re-enable the test disabled in #9100

Root cause: unmanagedNodes was computed as nodeCount-status.ready, where nodeCount includes tainted nodes but status.ready from the CA ConfigMap excludes them. Fixed by using isNodeTainted() to count only untainted nodes, matching CAs own view of the cluster

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[yashrajshuklaaa]

/release-note-none

[yashrajshuklaaa]

hi @vadasambar @feiskyer pls review this

[jackfrancis]

/ok-to-test

[yashrajshuklaaa]

/retest

[Choraden]

Hi @yashrajshuklaaa Thanks for the contribution.

Unfortunately, I don't believe it's right.
Notice that the nodeCount is obtained in the following way:

nodes, err := e2enode.GetReadySchedulableNodes(ctx, c)
framework.ExpectNoError(err)

if !nodeCountSet {
	// Guard the same number of schedulable nodes in every test case.
	nodeCount = len(nodes.Items)
	gomega.Expect(nodes.Items).ToNot(gomega.BeEmpty(), "Initial cluster must have at least one schedulable node")
	nodeCountSet = true
	ginkgo.By(fmt.Sprintf("Captured initial cluster size: %v", nodeCount))
}

If we take a look at the definition, we will find that the nodes are already filtered with isNodeUntainted

func GetReadySchedulableNodes(ctx context.Context, c clientset.Interface) (nodes *v1.NodeList, err error) {
	logger := klog.FromContext(ctx)
	nodes, err = checkWaitListSchedulableNodes(ctx, c)
	if err != nil {
		return nil, fmt.Errorf("listing schedulable nodes error: %w", err)
	}
	Filter(nodes, func(node v1.Node) bool {
		return IsNodeSchedulable(logger, &node) && isNodeUntainted(logger, &node)
	})
	if len(nodes.Items) == 0 {
		return nil, fmt.Errorf("there are currently no ready, schedulable nodes in the cluster")
	}
	return nodes, nil
}

So your change should basically be a no-op for the test logic.

AFAIR the flakiness lies in CA sometimes not delivering the ScaleUp Status Update via K8s Event. Feel free to investigate that direction :).
Also FYI we have temporary issues with the E2E tests, so to get more reliable feedback I suggest waiting till #9470 is merged.

[yashrajshuklaaa]

Hi @Choraden
thank you for the thorough review and for pointing that out!

You're absolutely right - I missed that GetReadySchedulableNodes already filters via isNodeUntainted which makes my change effectively a no-op
i apologize for the oversight

I'll dig deeper into the CA ScaleUp Status Update delivery via K8s Events as you suggested and will also wait for #9470 to merge before re-running E2E tests to get cleaner feedback

I'll update this PR (or open a new one if the fix direction changes significantly) once I have a better understanding of the root cause
thanks again for the guidance!