PVCs using the ReadWriteOncePod access mode can only be referenced by a
single pod. When a pod is scheduled that uses a ReadWriteOncePod PVC,
return "Unschedulable" if the PVC is already in-use in the cluster.
To support preemption, the "VolumeRestrictions" scheduler plugin
computes cycle state during the PreFilter phase. This cycle state
contains the number of references to the ReadWriteOncePod PVCs used by
the pod-to-be-scheduled.
During scheduler simulation (AddPod and RemovePod), we add and remove
reference counts from the cycle state if they use any of these
ReadWriteOncePod PVCs.
In the Filter phase, the scheduler checks if there are any PVC reference
conflicts, and returns "Unschedulable" if there is a conflict.
This is a required feature for the ReadWriteOncePod beta. See for more context:
https://github.com/kubernetes/enhancements/tree/master/keps/sig-storage/2485-read-write-once-pod-pv-access-mode#beta
Tests scheduler enforcement of the ReadWriteOncePod PVC access mode.
- Creates a pod using a PVC with ReadWriteOncePod
- Creates a second pod using the same PVC
- Observes the second pod fails to schedule because PVC is in-use
- Deletes the first pod
- Observes the second pod successfully schedules
This patch aims to simplify decoupling "pkg/scheduler/framework/plugins"
from internal "k8s.io/kubernetes" packages. More described in
issue #89930 and PR #102953.
Some helpers from "k8s.io/kubernetes/pkg/controller/volume/persistentvolume"
package moved to "k8s.io/component-helpers/storage/volume" package:
- IsDelayBindingMode
- GetBindVolumeToClaim
- IsVolumeBoundToClaim
- FindMatchingVolume
- CheckVolumeModeMismatches
- CheckAccessModes
- GetVolumeNodeAffinity
Also "CheckNodeAffinity" from "k8s.io/kubernetes/pkg/volume/util"
package moved to "k8s.io/component-helpers/storage/volume" package
to prevent diamond dependency conflict.
Signed-off-by: Konstantin Misyutin <konstantin.misyutin@huawei.com>
In case two or more controllers share the informers created through InitTestScheduler,
it's not safe to start the informers until all controllers set their informer
indexers. Otherwise, some controller might fail to register their indexers
in time. Thus, it's responsibility of each consumer to make sure all informers
are started after all controllers had time to get initiliazed.
This is gross but because NewDeleteOptions is used by various parts of
storage that still pass around pointers, the return type can't be
changed without significant refactoring within the apiserver. I think
this would be good to cleanup, but I want to minimize apiserver side
changes as much as possible in the client signature refactor.
