chore(defaultevictor): add MatchExpressions compatibility to the namespaceselector by Fankhauserli · Pull Request #1853 · kubernetes-sigs/descheduler

Fankhauserli · 2026-03-19T09:15:19Z

Description

We noticed that the new NamespaceLabelSelector does not implement the MatchExpressions selector. This is vital for our workflow, as we need to use an exclusion label with a MatchExpression.

Our target configuration looks something like this:

matchExpressions: 
  - key: "deschedulerExclusion"
    operator: "NotIn"
    values: ["true"]

Currently, the descheduler only checks for MatchLabels:

if ev.args.NamespaceLabelSelector == nil || len(ev.args.NamespaceLabelSelector.MatchLabels) == 0 {}

This Pull Request updates the condition to account for MatchExpressions as well, and adds the corresponding tests to ensure the new behavior works as expected.

if ev.args.NamespaceLabelSelector != nil && (len(ev.args.NamespaceLabelSelector.MatchLabels) > 0 || len(ev.args.NamespaceLabelSelector.MatchExpressions) > 0) {}

Checklist

Please ensure your pull request meets the following criteria before submitting
for review, these items will be used by reviewers to assess the quality and
completeness of your changes:

linux-foundation-easycla · 2026-03-19T09:15:27Z

The committers listed above are authorized under a signed CLA.

✅ login: Fankhauserli / name: Linus Fankhauser (2348014, 95154ad)

k8s-ci-robot · 2026-03-19T09:15:29Z

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k8s-ci-robot · 2026-03-19T09:15:30Z

Hi @Fankhauserli. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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a7i · 2026-03-25T01:51:27Z

/ok-to-test

a7i · 2026-04-08T02:11:56Z

/lgtm

ingvagabund · 2026-05-11T10:13:34Z

 	})

-	fakeClient := fake.NewClientset(node, nsProd, nsBackend, nsTest, podInProd, podInBackend, podInTest)
+	fakeClient := fake.NewSimpleClientset(node, nsProd, nsBackend, nsTest, podInProd, podInBackend, podInTest)


Is this intentional? The newly written tests use NewSimpleClientset.

ingvagabund · 2026-05-11T10:18:19Z

+
+	fakeClient := fake.NewClientset(node, nsProd, nsTest, podInProd, podInTest)
+	sharedInformerFactory := informers.NewSharedInformerFactory(fakeClient, 0)
+	getPodAssignedToNode, _ := podutil.BuildGetPodsAssignedToNodeFunc(sharedInformerFactory.Core().V1().Pods().Informer())


Probably rare to fail here but still good practice to check the error

ingvagabund · 2026-05-11T10:24:07Z

+	testCases := []struct {
+		name    string
+		args    *DefaultEvictorArgs
+		results map[string]bool // pod name -> should pass PreEvictionFilter


What about to create a list of pointers to pods to pass and not pass to make the selection more explicit instead of constructing it at the end? To make the test easier to read.

ingvagabund · 2026-05-11T10:27:46Z

+	nsNoLabels.Labels = map[string]string{}
+
+	podInProd := test.BuildTestPod("pod-in-prod", 100, 100, node.Name, func(pod *v1.Pod) {
+		pod.Namespace = "ns-prod"


pod.Namespace = nsProd.Name to avoid duplicating the string literal. The same for other occurences.

ingvagabund · 2026-05-11T10:31:30Z

+	nsNoLabels := test.BuildTestNamespace("ns-nolabels")
+	nsNoLabels.Labels = map[string]string{}
+
+	podInProd := test.BuildTestPod("pod-in-prod", 100, 100, node.Name, func(pod *v1.Pod) {


s/podInProd/podInProdFrontend to make it explicit. The same for other occurences.

ingvagabund · 2026-05-11T10:32:32Z

+	defer cancel()
+	node := test.BuildTestNode("node1", 1000, 2000, 10, nil)
+
+	podProd := test.BuildTestPod("pod-prod", 100, 100, node.Name, func(pod *v1.Pod) {


ditto. s/podProd/podProdFrontend and other occurences

ingvagabund · 2026-05-11T10:32:40Z

+	testCases := []struct {
+		name    string
+		args    *DefaultEvictorArgs
+		results map[string]bool // pod name -> should pass Filter


ingvagabund · 2026-05-11T10:34:26Z

The first commit introduces a lot of test code that is then removed/updated in the second commit. Can you please either squash the commits or make the new tests part of a single commit?

ingvagabund · 2026-05-11T10:34:59Z

@Fankhauserli thank you for the code changes and welcome as a contributor

…selector

ingvagabund · 2026-05-18T11:14:43Z

/approve
/lgtm

k8s-ci-robot · 2026-05-18T11:14:52Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ingvagabund

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k8s-ci-robot added cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. size/L Denotes a PR that changes 100-499 lines, ignoring generated files. needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Mar 19, 2026

k8s-ci-robot requested review from JaneLiuL and damemi March 19, 2026 09:15

k8s-ci-robot added cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. and removed cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. labels Mar 19, 2026

anthony-spruyt mentioned this pull request Mar 22, 2026

feat(descheduler): switch namespace exclusions to label selectors anthony-spruyt/spruyt-labs#641

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k8s-ci-robot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Mar 25, 2026

k8s-ci-robot assigned a7i Apr 8, 2026

k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Apr 8, 2026

a7i added the tide/merge-method-squash Denotes a PR that should be squashed by tide when it merges. label Apr 8, 2026

ingvagabund reviewed May 11, 2026

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chore(defaultevictor): add matchlabels compatibility to the namespace…

dbb7eb4

…selector

Fankhauserli force-pushed the master branch from 95154ad to dbb7eb4 Compare May 18, 2026 09:07

k8s-ci-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label May 18, 2026

k8s-ci-robot assigned ingvagabund May 18, 2026

k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label May 18, 2026

k8s-ci-robot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label May 18, 2026

k8s-ci-robot merged commit 6b5f6b4 into kubernetes-sigs:master May 18, 2026
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Fankhauserli commented Mar 19, 2026

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