Automatic merge from submit-queue
Initial support for pod eviction based on disk
This PR adds the following:
1. node reports disk pressure condition based on configured thresholds
1. scheduler does not place pods on nodes reporting disk pressure
1. kubelet will not admit any pod when it reports disk pressure
1. kubelet ranks pods for eviction when low on disk
1. kubelet evicts greediest pod
Follow-on PRs will need to handle:
1. integrate with new image gc PR (https://github.com/kubernetes/kubernetes/pull/27199)
1. container gc policy should always run (will not be launched from eviction, tbd who does that)
1. this means kill pod is fine for all eviction code paths since container gc will remove dead container
1. min reclaim support will just poll summary provider (derek will do follow-on)
1. need to know if imagefs is same device as rootfs from summary (derek follow-on)
/cc @vishh @kubernetes/sig-node
When kubelet starts a pod that refers to non-existing PV, PVC or Node, it
should clearly show that the requested element does not exist.
Previous "PersistentVolumeClaim 'default/ceph-claim-wm' is not in cache"
looks like random kubelet hiccup, while "PersistentVolumeClaim
'default/ceph-claim-wm' not found" suggests that the object may not exist at
all and it might be an user error.
Fixes#27523
Implements part of #24071
I am not familiar with the scheduler enough to know what to do with the scores. Punting for now.
Missing items from the implementation plan: limitranger, rkt support, kubectl
support and user docs
DONE:
1. refactor all predicates: predicates return fitOrNot(bool) and error(Error) in which the latter is of type
PredicateFailureError or InsufficientResourceError. (For violation of either MaxEBSVolumeCount or
MaxGCEPDVolumeCount, returns one same error type as ErrMaxVolumeCountExceeded)
2. GeneralPredicates() is a predicate function, which includes serveral other predicate functions (PodFitsResource,
PodFitsHost, PodFitsHostPort). It is registered as one of the predicates in DefaultAlgorithmProvider, and
is also called in canAdmitPod() in Kubelet and should be called by other components (like rescheduler, etc)
if necessary. See discussion in issue #12744
3. remove podNumber check from GeneralPredicates
4. HostName is now verified in Kubelet's canAdminPod(). add TestHostNameConflicts in kubelet_test.go
5. add getNodeAnyWay() method in Kubelet to get node information in standaloneMode
TODO:
1. determine which predicates should be included in GeneralPredicates()
2. separate GeneralPredicates() into:
a. GeneralPredicatesEvictPod() and
b. GeneralPredicatesNotEvictPod()
3. DaemonSet should use GeneralPredicates()
mksalawa