Change:
) var ( <del> emptyFunc = func(bool) {} </del> <ins> emptyFunc             = func(bool) {} coreNamespaceResource = schema.GroupResource{Group: "", Resource: "namespaces"} </ins> ) const (

Discussion:
We upgraded our test cluster to (GKE ) and noticed that some of our tests began to time out when watching for events that never arrived. Upon investigation, it appears that there is a regression in the deprecated path-based watch API for at least e.g. . We have not been able to reproduce this with any other resource type. When creating a watch for a namespace (see ) we see the initial event, but then we do not see subsequent events if we modify the namespace e.g. add a label or annotation. I would expect to see events when the namespace is altered. E.g. adding a label should produce a event with the contents. a new test namespace e.g. a proxy to the master the watch path of the namespace that has been created e.g. another shell, modify the namespace to add a label to it. that there is no modified event in the watch. It is understood that the based paths are and have been for some time deprecated, we are working on moving to use the watch query param instead. <detailsWe are using Google Kubernetes Engine, please see version above. </detailsNo response No response No response No response
/sig api-machinery
The addWatcher add watch to allWatchers with with the value namespace not empty. But the function dispatch event with an empty namespace.
This issue is limited to watchers of the core namespace resource using the deprecated endpoint and watching a single namespace. This was introduced in 1.27 in (which was merged with test coverage in 1.27 in )
Hi, just to confirm this was working fine (and still is on our production clusters) on 1.28.7 it's only since 1.28.8 that we can see this bug, so slightly confused by your comment (and issue rename) to say 1.27+?
I reproduced the break at HEAD of release-1.27, and assumed the break came in with , but I was wrong.

release-1.26 HEAD: works v1.27.0: works release-1.27 HEAD: broken v1.28.0: works v1.28.7: works per your feedback v1.28.8: breaks per your feedback release-1.28 HEAD: broken That means that watch cache changes cherry picked back to 1.27 and 1.28 regressed something, and I don't know exactly what the breaking change was. The only thing that looks at all relevant between 1.28.7 and 1.28.8 is , but I don't see how that would only impact the single-item watch cc
Did you send the request with a resource version, or any other parameter? If the parameter is not empty, will work, or the old watcher will work. This makes a big difference.
This commit add the feature gate .
No, I just sent and that broke somewhere between 1.27.0 and
If you are asking me, I did not send any additional query parameter, no. On our cluster: works as expected, we see events when we add labels etc. On our cluster: does not work, we do not see events.
Ok, figured it out... 27.0 which is what made the watch cache not handle correctly (merged in with test coverage) also which routed watch requests without a resourceVersion parameter directly to etcd, bypassing watch cache 27.13 / 1.28.9 / 1.29.4 / 1.30.0 moved the behavior from behind an off-by-default gate because it was a massive performance regression. This had the side effect of making watch requests without a resourceVersion parameter get handled by the watch cache, and get exposed to this issue.

(GKE accelerated that specific fix internally to resolve that performance regression, so it showed up in a GKE 1.28.8-gke.X build, which is what confused me when looking for the delta between v1.28.7 and v1.28.8) in [1.27.0-1.12.12], [1.28.0-1.28.8], [1.29-1.29.3]: routes to etcd and works (because of ) routes to etcd and works (because of ) routes to watch cache and fails (where X is not 0) routes to watch cache and failsin 1.27.13+, 1.28.9+, 1.29.4+, 1.30.0+: routes to watch cache and fails routes to watch cache and fails routes to watch cache and fails (where X is not 0) routes to watch cache and fails
The workaround for anyone encountering this issue is to use the non-deprecated watch endpoint (and is a generally good change to make anyway) The Kubernetes fix for this I would recommend to restore pre-1.27 behavior is in my comment in Once that is done and test coverage , I'd be happy to see that backported to 1.27+
/cc
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/assign
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just to verify, are you planning to take to completion?

if so, it would be ideal to complete that so the 1.27 backport can happen before 1.27 reaches EOL in June
I saw I was assigned with this issue. Taking a look...
sorry, was tagging you in since you helped bring in and might have context, but realized I should check with first since they have a fix in progress
Yew, working on it and writing test case.
cc
is this issue resolved already?
Not yet, is the proposed fix, under review now