kube-proxy: initialization wait for service and endpoint handlers synced

[wedaly]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Ensure kube-proxy waits for the services/endpointslices informer caches to be synced and all pre-sync events delivered before setting isInitialized=true. Otherwise, in clusters with many services, some services may be missing from svcPortMap when kube-proxy starts (e.g. during daemonset rollout). This can cause kube-proxy to temporarily remove service DNAT rules and then skip cleanup of UDP conntrack entries to a service VIP.

Which issue(s) this PR fixes:

Fixes #126468

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Fix race condition in kube-proxy initialization that could blackhole UDP traffic to service VIP.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

N/A

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[aojea]

/ok-to-test
/assign @aojea @danwinship

[aojea]

@wedaly there are another two handlers for Nodes and ServiceCIDRs that may face similar problems, do you mind fixing all of them ?

---

EDIT Nevermind, we want to backport this, so better leave it this way

/lgmt

@danwinship for approval

[wedaly]

EDIT Nevermind, we want to backport this, so better leave it this way

makes sense! I'm also happy to update the other handlers in a follow-on PR.

[aojea]

This is milestone v1.32 and we backport later, since is not a new bug or a regression

/milestone v1.32
/approve

This is a bug that was fixed in 1.27 already in most of the controllers #113985
, just nobody realized kube-proxy needed to be updated at that time , thanks @wedaly for fixing it

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aojea, wedaly

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• pkg/proxy/OWNERS [aojea]

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[wedaly]

EDIT Nevermind, we want to backport this, so better leave it this way

makes sense! I'm also happy to update the other handlers in a follow-on PR.

follow-on PR is here: #126561

[aojea]

/retest

[aojea]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 4b65fb851918241dcbc4c07fd9088824b808e367