Code change:
<!-- Please only use this template for submitting reports about flaky tests or jobs (pass or fail with no underlying change in code) in Kubernetes CI --k8s-e2e-ltsc2019-containerd-flannel-sdnoverlay-master [] Container Lifecycle Hook when create a pod with lifecycle hook should execute prestart http hook properly [NodeConformance] [Conformance] [] Container Lifecycle Hook when create a pod with lifecycle hook should execute poststart http hook properly [NodeConformance] [Conformance] Note: the tests have been excluded until they are fixed. In the case of multinode clusters, the http server pod and the test cluster can spawn on different nodes, which can be problematic for poststart / prestop hooks, as they are executed by the kubelet itself, and the cross-node lifecycle hook might fail (according to the [Kubernetes network model], it is not mandatory for kubelet to be able to access pods on a different node). However, that is not always the case, different Networking setups allow cross-node communication between kubelet and pods, which means that the above tests are passing properly (for example: ), which begs the question if this behaviour should be universal or not, especially since the tests are marked as , which would imply that it should work in all cases. [Kubernetes network model]: links to appreciated links to specific failures in spyglass appreciated Slack: /sig testing /sig networking /sig windows &lt;!-- Please see the deflaking doc () for more guidance! --
/sig network /sig node /area conformance /assign /priority critical-urgent /cc This is important since affects conformance and defines the networking behaviour for the poststart/ prestop hooks
The label(s) cannot be applied, because the repository doesn't have them. &lt;detailsIn response to : /sig network /sig node /sig conformance /assign /priority critical-urgent /cc Instructions for interacting with me using PR comments are available . If you have questions or suggestions related to my behavior, please file an issue against the repository. &lt;/details
i'd personally let folks have first dibs on what we need to do here. Though from the name of the test itself, it seems like the test is NOT a sig-network test :)
Indeed, it does not have any tag in its name, but the tests rely on networking and on how CNIs work. As I've stated above, it's not a problem for flannel sdnbridge, but it is for flannel sdnoverlay; other CNIs might have a similar issue too.
because the network is not a thing :) let´s tag the sig owner then /sig node I think that the key here is to decide if kubelet should be able to access pod in other nodes, and based on the link Claudiu is part of the Kubernetes networking model. I saw users that doesn't want kubelet to access even the pods on same host, so I think that is legit to say kubelet MAY reach pods in other nodes but not MUST ... but I'm not familiar with the to fully understand the context. If kubelet "may" reach pods in the other nodes, the test must only test lifecycle hooks for pods in the same node as the kubelet under test, right?
This is correct. The model also says: "For those platforms that support Pods running in the host network (e.g. Linux): pods in the host network of a node can communicate with all pods on all nodes without NAT" I believe that Windows host network is not supported, right?
Right, and there are specific tests that checks that exact scenario you've mentioned: However, the flaky tests I've mentioned in the issue require kubelet to be able to dial-in into a webserver pod for a different pod's poststart / prestop HTTP lifecycle hooks. There are couple of things regarding this: of all, in order to ensure kubelet would be able to run the HTTP lifecycle hooks, we'd have to make sure both pods are on the same node, as that is a supported scenario, according to the Kubernetes Network Model. I have sent a PR for this above. Alternatively, a Cluster IP could probably work as well, but IMO, ensuring that both pods end up on the same node is simpler and easier to clean up. , it's interesting that those HTTP lifecycle hook tests work on different networking setups, without any pods having HostNetwork enabled, even though you've mentioned they should (e.g.: Linux / Windows with flannel l2bridge, and even Linux with flannel overlay). Now, my question is: is this behaviour a feature, or a bug, especially since the tests are marked as `?
oh, I missed that part, so in Linux kubelet must be able to communicate with pods on all nodes (becuase it is running in the hostnetwork) If that is correct, it seems that one solution is to keep the test for Linux and tag it as LinuxOnly, and a new test for WindowsOnly that only spawn the pods under test in the same node EDIT Discussed in sig-net meeting , no clear answer... can be kubelet considered as a hostnetwork pod?
For the purposes of testing, I don't mind forcing the pods onto the same node., but let's document the heck out of that at the code-site?
correct but it will be supported once HostProcess containers are merged in 1.22: Only in Overlay networks (ie Flannel where these tests are flaking) does the pod have to be on the same node. It doesn't require host network mode and these tests are . I would be more inclined to disable this test for Windows Overlay test setups and have a sig-windows test for the overlay functionality. I would also question if the lifecycle hooks only running on the same node is useful and if it should just be documented that it doesn't work in the Windows Overlay setup.
is looking at test PRs from SIG Node. I will let sig-net triage this issue
Next steps on this?
/triage accepted
We still haven't merged this: I also had this, but it has been decided to be blocked:
requires conformance approval, at this point I think that has to be postponed to 1.23 right, since that behavior is not required, we shouldn't test it, because is legit to fail and having a test for something that can fail can create confusion :smile:

Related discussion:
text: hook should execute poststart http hook properly [NodeConformance] [Conformance]' description: When a post start handler is specified in the container lifecycle using a HttpGet action, then the handler MUST be invoked after the start of the container. <del> A server pod is created that will serve http requests, create a second pod with a container lifecycle specifying a post start that invokes the server pod to validate that the post start is executed. </del> <ins> A server pod is created that will serve http requests, create a second pod on the same node with a container lifecycle specifying a post start that invokes the server pod to validate that the post start is executed. </ins> release: v1.9 file: test/e2e/common/node/lifecycle_hook.go - testname: Pod Lifecycle, prestop exec hook