Add topologySpreadConstraints configuration to pod spec. by laiminhtrung1997 · Pull Request #2530 · zalando/postgres-operator

laiminhtrung1997 · 2024-02-04T15:34:46Z

Dear all,

I think we should configure topologySpreadConstraints to pod spec so these pods can spread zones for high availability.

Could someone review it, please? Thank you very much.

Best regards.

monotek · 2024-05-16T11:22:19Z

We need that feature too.

FxKu · 2024-06-26T13:39:50Z

pkg/cluster/cluster.go

 	}
+	if !reflect.DeepEqual(c.Statefulset.Spec.Template.Spec.TopologySpreadConstraints, statefulSet.Spec.Template.Spec.TopologySpreadConstraints) {
+		needsReplace = true
+		needsRollUpdate = true


does this really need to trigger a rolling update of pods executed by operator? Will not K8s take care of it then once the statefulset is replaced?

I see, but is this wrong too?
https://github.com/zalando/postgres-operator/blob/master/pkg/cluster/cluster.go#L472

hm good point. Maybe we can leave as is for now. With rolling update we make sure pods immediately adhere the new constraints.

FxKu · 2024-06-26T13:43:49Z

pkg/apis/acid.zalan.do/v1/postgresql_type.go

 	InitContainersOld       []v1.Container `json:"init_containers,omitempty"`
 	PodPriorityClassNameOld string         `json:"pod_priority_class_name,omitempty"`
+
+	TopologySpreadConstraints []v1.TopologySpreadConstraint `json:"topologySpreadConstraints,omitempty"`


when introducing new fields to the api you have to update the CRDs, too. Unfortunately, we don't use a modern framework where this can be generated and you have to the manifests and in go code.

Plus, you need to run code generation -> ./hack/update-codegen.sh

FxKu · 2024-06-26T13:45:26Z

pkg/cluster/k8sres.go

 		false,
 		"",
 		false,
+		[]v1.TopologySpreadConstraint{},


atm we reuse configured tolerations also for logical backup so I guess we can do the same with constraints

Ok I got it.

FxKu · 2024-06-26T13:46:17Z

pkg/cluster/k8sres.go

 	return podAntiAffinity
 }

+func generateTopologySpreadConstraints(labels labels.Set, topologySpreadConstraintObjs []v1.TopologySpreadConstraint) []v1.TopologySpreadConstraint {


would like to see a unit test for this function :)

I added a unit test for this function.

FxKu · 2024-06-26T13:47:40Z

Can you also write an e2e test that tests that the constraints work as expected, please?

laiminhtrung1997 · 2024-06-27T08:34:56Z

Can you also write an e2e test that tests that the constraints work as expected, please?

Dear @FxKu
Thanks so much for your comments, I haven't written the UT or e2e test many, but I'll try my best. I'll mark it ready and let you know when I fixed the comments.
Best regards.

FxKu · 2025-10-15T13:52:56Z

Can you please provide

an example in the complete manifest (somewhere here)
support in helm chart
add documentation behind this paragraph

FxKu · 2025-10-15T14:08:39Z

e2e/tests/test_e2e.py

+            }
+        }
+        k8s.api.core_v1.patch_node(master_nodes[0], patch_node_label)
+        k8s.api.core_v1.patch_node(replica_nodes[0], patch_node_label)


I would expect that the e2e test patches the Postgresql manifest and adds topologySpreadConstraints to then check if the pods spread evenly. But you're only patching the nodes here?

I updated the e2e test.

zalando-robot · 2025-10-19T07:24:42Z

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laiminhtrung1997 · 2025-10-19T08:07:26Z

Can you please provide

an example in the complete manifest (somewhere here)

support in helm chart

add documentation behind this paragraph

Dear @FxKu
I completed the requests above. Please review it.

zalando-robot · 2025-12-16T09:06:59Z

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…ls manifest.

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lenglet-k · 2026-03-18T11:49:56Z

Hello,

what's the next for this issue ?

laiminhtrung1997 requested review from FxKu, Jan-M, hughcapet, idanovinda, jopadi, macedigital and sdudoladov as code owners February 4, 2024 15:34

laiminhtrung1997 force-pushed the add-topologySpreadConstraints branch 2 times, most recently from b948c94 to 44fcb1f Compare February 4, 2024 16:16

laiminhtrung1997 mentioned this pull request Feb 4, 2024

Add topologySpreadConstraints configuration. #2474

Closed

FxKu added this to the 2.0 milestone Feb 13, 2024

FxKu modified the milestones: 2.0, 1.13.0 May 24, 2024

FxKu reviewed Jun 26, 2024

View reviewed changes

FxKu modified the milestones: 1.13.0, 1.14.0 Jun 26, 2024

laiminhtrung1997 force-pushed the add-topologySpreadConstraints branch 8 times, most recently from 530f847 to 18023cb Compare July 7, 2024 06:56

FxKu reviewed Oct 15, 2025

View reviewed changes

laiminhtrung1997 added 15 commits March 13, 2026 20:03

Add topologySpreadConstraints configuration to pod spec.

101d42f

Modify the UT.

30d8802

Correct the assert with the list of constraints.

72f643f

Fix UT

0412edf

Run update-codegen.sh to add deepcopy for new field to the api.

6c669fe

Reuse configured TopologySpreadConstraints for logical backup.

612f769

Remove x-kubernetes-preserve-unknown-fields and XPreserveUnknownFields.

37bfa71

Remove unnecessary len check.

0518b6d

Add topologySpreadConstraint example in the complete manifest.

25001c7

Add support for helm chart.

a7d4921

Add documentation for topologySpreadConstraint.

c08ce4d

Update e2e test to patch topologySpreadConstraints into the postgresq…

d09bd09

…ls manifest.

Revert unnecessary change.

6930464

Updated the PVC retention policy to remove redundant PVCs.

c162b59

Fix expected PVC count in end-to-end test after config changes.

4ea42a0

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laiminhtrung1997 commented Feb 4, 2024 •

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