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Update proposal with info. about flex, localstorage etc 

Also clarify about controller resize
This commit is contained in:
Hemant Kumar 2017-07-23 12:47:58 -04:00
parent dd27307dce
commit a8fed8c733
1 changed files with 9 additions and 4 deletions
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13
contributors/design-proposals/grow-volume-size.md
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@ -34,6 +34,9 @@ Enable users to increase size of PVs that their pods are using. The user will up
| Azure File | No | No | No | | Azure File | No | No | No |
| Cephfs | No | No | No | | Cephfs | No | No | No |
| NFS | No | No | No | | NFS | No | No | No |
| Flex | Yes | Maybe | No |
| LocalStorage | Yes | Yes | No |
| Block device | Yes | No | No |
## Implementation Design ## Implementation Design
@ -49,7 +52,7 @@ For volume types that only require volume plugin based api call, this will be on
* `pvc.spec.resources.requests.storage` field of pvc object will become mutable after this change. * `pvc.spec.resources.requests.storage` field of pvc object will become mutable after this change.
* #sig-api-machinery has agreed to allow pvc's status update from kubelet as long as pvc and node relationship * #sig-api-machinery has agreed to allow pvc's status update from kubelet as long as pvc and node relationship
can be validated by node authorizer. can be validated by node authorizer.
* This feature will be protected by an alpha feature gate. * This feature will be protected by an alpha feature gate, so as API changes needed for it.
### Admission Control and Validations ### Admission Control and Validations
@ -66,6 +69,7 @@ new controller will be:
* Watch for pvc update requests and add pvc to controller's desired state of world if a increase in volume size was requested. Once PVC is added to * Watch for pvc update requests and add pvc to controller's desired state of world if a increase in volume size was requested. Once PVC is added to
controller's desired state of world - `pvc.Status.Conditions` will be updated with `ResizeStarted: True`. controller's desired state of world - `pvc.Status.Conditions` will be updated with `ResizeStarted: True`.
* For unbound or pending PVCs - resize will trigger no action in `volume_expand_controller`. * For unbound or pending PVCs - resize will trigger no action in `volume_expand_controller`.
* If `pv.Spec.Capacity` already is of size greater or equal than requested size, similarly no action will be perfomed by the controller.
* A reconciler will read desired state of world and perform corresponding volume resize operation. If there is a resize operation in progress * A reconciler will read desired state of world and perform corresponding volume resize operation. If there is a resize operation in progress
for same volume then resize request will be pending and retried once previous resize request has completed. for same volume then resize request will be pending and retried once previous resize request has completed.
* Controller resize in effect will be level based rather than edge based. If there are more than one pending resize request for same PVC then * Controller resize in effect will be level based rather than edge based. If there are more than one pending resize request for same PVC then
@ -210,6 +214,10 @@ spec:
In addition to that PVC's status will have a `Conditions []PvcCondition` - which will be used In addition to that PVC's status will have a `Conditions []PvcCondition` - which will be used
to communicate the status of PVC to the user. to communicate the status of PVC to the user.
The API change will be protected by Alpha feature gate and api-server will not allow PVCs with
`Status.Conditions` field if feature is not enabled. `omitempty` in serialization format will
prevent presence of field if not set.
So the `PersistentVolumeClaimStatus` will become: So the `PersistentVolumeClaimStatus` will become:
```go ```go
@ -248,6 +256,3 @@ const (
This proposal relies on ability to update PVC status from kubelet. While updating PVC's status This proposal relies on ability to update PVC status from kubelet. While updating PVC's status
a PATCH request must be made from kubelet to update the status. a PATCH request must be made from kubelet to update the status.
Also - an Admin can directly edit the PV and specify new size but controller will not perform
any automatic resize of underlying volume or file system in such cases.