Change:
// ServerResourcesForGroupVersion returns the supported resources for a group and version. func (d *DiscoveryClient) ServerResourcesForGroupVersion(groupVersion string) (resources *unversioned.APIResourceList, err error) { url := url.URL{} <del> if groupVersion == "v1" { </del> <ins> if len(groupVersion) == 0 { return nil, fmt.Errorf("groupVersion shouldn't be empty") } else if groupVersion == "v1" { </ins> url.Path = "/api/" + groupVersion } else { url.Path = "/apis/" + groupVersion

Discussion:
I have been having the kube-controller-manager (running in a container) crash quite frequently with this error: I cant fathom what seems to cause it. It seems to happen consistently for a while (CrashLoopBackoff occurs) and then fixes itself after an undetermined amount of time. Kubectl version: Docker version: Networking: Calico (with the calico k8s policy agent) Please do let me know if there is any other information that I can supply. I appreciate I haven't given much to go off of. I am not sure what the steps to reproduce are...
cc
It looks like a bug. I'll take a look. Thanks for reporting it.
Weirdly, the description showed up in the email github sent me but it appears absent on the github issue?
The description was there when I read it but disappeared now.
Well thats very odd! If you have it on your email, could you post it on here please (and I will update the description)? I unfortunately haven't got the error message to hand now...
I took the liberty of just editing the OP.
thanks a lot! Not sure what happened there!
could you paste the returned output at "server-ip:port/api" and "server-ip:port/apis"?
Sure.
Thanks "" has an empty preferred version and that's causing the error you reported. Is "" created via the thirdparty resource api? ()
aha! Good spot! Yes, it was created via that API. This is the Yaml file I used to create it: Here is the output of
Thanks for the confirmation Your configuration is correct. The preferred version is left empty by the thirdparty resource controller, while our discovery client has an assumption that the preferred version won't be empty. I'll patch the discovery client to tolerate an empty preferred version, and will discuss with on if we should make a default preferred version for a thirdparty resource.
Thanks a lot Great job on working it out :)
Sent to fix.
What would be a workaround for this before the release, how can one specify the preferredVersion?
AFAIK, there is no workaround. There is no way to specify the preferredVersion for the thirdPartyResource.

I have a quick workaround to fix this : 1) Change the kubernetes to reflect the following : from : thirdpartyresources=true to : thirdpartyresources=false 2) Then restart 'kubelet' service OR reboot the K8S Master server systemctl restart kubelet 3) Revert back the changes done to kube- from : thirdpartyresources=false to : thirdpartyresources=true 4) Verify whether the above change on the above manifest file has been automatically picked up by the kubernetes API ps aux | grep -i thirdpartyresources 5) Finally you may restart kubelet service systemctl restart kubelet 6) Now verify whether the 'kube-controller-manager' is in a 'Running' state kubectl get pods --all-namespaces | grep -i controller-manager Hope this fix works for you guys as well !!