[Bug] stormservice's headless service need set PublishNotReadyAddresses

[bigerous]

Pull Request Description

StormServiceController will Create a headless service assocaited with stormservice. The headless service's publishNotReadyAddresses option is false (by default), only ready Pods get listed in DNS. This will cause pod of the same stormservice can not reach each other by dns name like <pod-name>.<service-name>.<namespace>.svc.cluster.local before target pod is ready. Reaching another pod by dns name before pod is ready is needed in some cases like sglang's multi-node deployment:

# replace 172.16.4.52:20000 with your own node ip address and port of the first node

python3 -m sglang.launch_server --model-path meta-llama/Meta-Llama-3.1-405B-Instruct --tp 16 --dist-init-addr {ROLESET_NAME}-${ROLE_NAME}-${ROLE_TEMPLATE_HASH}-${ROLE_REPLICA_INDEX}-0.${STORM_SERVICE_NAME}:5000 --nnodes 2 --node-rank 0

python3 -m sglang.launch_server --model-path meta-llama/Meta-Llama-3.1-405B-Instruct --tp 16 --dist-init-addr {ROLESET_NAME}-${ROLE_NAME}-${ROLE_TEMPLATE_HASH}-${ROLE_REPLICA_INDEX}-0.${STORM_SERVICE_NAME}:5000  --nnodes 2 --node-rank 1

When publishNotReadyAddresses is true: Pods that aren’t ready yet (per readiness probes) will also be included in the DNS entries for the service.

Related Issues

Resolves: #[Insert issue number(s)]

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[gemini-code-assist]

Summary of Changes

Hello @bigerous, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug where pods within the same stormservice could not communicate via DNS before all target pods were fully ready. The change enables the publishNotReadyAddresses option on the headless service associated with stormservice instances. This ensures that DNS entries for the service include unready pods, facilitating scenarios like multi-node deployments (e.g., sglang) that require pods to resolve each other's DNS names even if they are not yet in a 'ready' state.

Highlights

• Headless Service Configuration: The PublishNotReadyAddresses field for the StormService's headless service is now set to true. This ensures that even unready pods are included in the DNS entries, allowing for inter-pod communication via DNS before all pods are fully ready.

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[gemini-code-assist]

Code Review

This pull request aims to fix a bug where pods of a stormservice cannot discover each other via DNS before they are ready. The proposed change correctly sets PublishNotReadyAddresses: true on the headless service spec. However, the review identified a significant issue: the change will not be applied to existing services because the equality check function (isServiceEqual) does not compare this new field. This makes the fix incomplete. I've provided a detailed comment on how to correct this, which involves updating isServiceEqual and the associated unit tests.

[gemini-code-assist]

While adding PublishNotReadyAddresses: true is correct for the intended purpose, the current implementation will not apply this change to existing headless services.

The isServiceEqual function, which is used to check if an update is needed, does not compare the PublishNotReadyAddresses field. As a result, the controller will not detect the difference for existing services and will not trigger an update. This makes the bug fix incomplete as it won't work for existing StormService resources.

To fix this, isServiceEqual in pkg/controller/stormservice/utils.go needs to be updated to include this check:

// isServiceEqual compares two Kubernetes Service objects for equality
func isServiceEqual(a, b *corev1.Service) bool {
	return a.Spec.Type == b.Spec.Type &&
		apiequality.Semantic.DeepEqual(a.Spec.Selector, b.Spec.Selector) &&
		a.Spec.ClusterIP == b.Spec.ClusterIP &&
		a.Spec.PublishNotReadyAddresses == b.Spec.PublishNotReadyAddresses
}

Additionally, the test TestSyncHeadlessService in pkg/controller/stormservice/sync_test.go should be updated to assert that PublishNotReadyAddresses is set to true on the created/updated service to prevent future regressions.

[Jeffwan]

@bigerous could you check the utils. for existing services, once user finish the upgrade, the service can be updated.

[bigerous]

Got it. I have updated the utils and add ut test for this case.