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Inline design updates 

Signed-off-by: Deep Debroy <ddebroy@docker.com>
This commit is contained in:
Deep Debroy 2019-04-22 16:01:08 -07:00
parent 988632b197
commit 344a99aa5b
1 changed files with 25 additions and 7 deletions
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32
contributors/design-proposals/storage/csi-migration.md
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@ -179,6 +179,10 @@ type CSITranslator interface {
// by the `Driver` field in the CSI Source. The input PV object will not be modified. // by the `Driver` field in the CSI Source. The input PV object will not be modified.
TranslateCSIPVToInTree(pv *v1.PersistentVolume) (*v1.PersistentVolume, error) { TranslateCSIPVToInTree(pv *v1.PersistentVolume) (*v1.PersistentVolume, error) {
// TranslateInTreeVolumeToCSI takes an inline intree volume and will translate
// the in-tree volume source to a CSIPersistentVolumeSource
// A PV object containing the CSIPersistentVolumeSource in it's spec is returned
TranslateInTreeInlineVolumeToCSI(volume *v1.Volume (*v1.PersistentVolume, error) {
// IsMigratableByName tests whether there is Migration logic for the in-tree plugin // IsMigratableByName tests whether there is Migration logic for the in-tree plugin
// for the given `pluginName` // for the given `pluginName`
@ -187,11 +191,15 @@ type CSITranslator interface {
// GetCSINameFromIntreeName maps the name of a CSI driver to its in-tree version // GetCSINameFromIntreeName maps the name of a CSI driver to its in-tree version
GetCSINameFromIntreeName(pluginName string) (string, error) { GetCSINameFromIntreeName(pluginName string) (string, error) {
// GetAccessModeForVolume returns a reasonable access mode based on readonly flag
GetAccessModeForVolume(readOnly bool, pluginName string) (csi.VolumeCapability_AccessMode, error) {
// GetMountOptions returns a reasonable access mode based on readonly flag
GetMountOptions(pluginName string) (string) {
// IsPVMigratable tests whether there is Migration logic for the given Persistent Volume // IsPVMigratable tests whether there is Migration logic for the given Persistent Volume
IsPVMigratable(pv *v1.PersistentVolume) bool { IsPVMigratable(pv *v1.PersistentVolume) bool {
// IsInlineMigratable tests whether there is Migration logic for the given Inline Volume // IsInlineMigratable tests whether there is Migration logic for the given Inline Volume
IsInlineMigratable(vol *v1.Volume) bool { IsInlineMigratable(vol *v1.Volume) bool {
} }
@ -237,15 +245,23 @@ with the in-tree plugin, the VolumeAttachment object becomes orphaned.
### In-line Volumes ### In-line Volumes
In-line controller calls are a special case because there is no PV. In this case In-line controller calls are a special case because there is no PV. In this case
we will translate the volume source and copy it to the field we will translate the in-line volume source into a CSIPersistentVolumeSource
VolumeAttachment.Spec.Source.VolumeAttachmentSource.InlineVolumeSource. The and copy it to the field `VolumeAttachment.Spec.Source.VolumeAttachmentSource.InlineCSIVolumeSource`.
VolumeAttachment name must be made with the CSI Translated version of the The VolumeAttachment name must be made with the CSI Translated version of the
VolumeSource in order for it to be discoverable by Detach and WaitForAttach VolumeSource in order for it to be discoverable by Detach and WaitForAttach
(described in more detail below). (described in more detail below).
The CSI Attacher will have to be modified to also check this location for a The CSI Attacher will have to be modified to also check for `InlineCSIVolumeSource`
source as well as checking for the `pvName`. Only one of the two may be besides the `PersistentVolumeName`. Only one of the two may be specified. If `PersistentVolumeName`
specified. is empty and `InlineCSIVolumeSource` is set, the CSI Attacher will not look for
an associated PV in it's PV informer cache as it implies the inline volume scenario
(where no PVs are created).
The CSI Attacher will have access to most of the data it requires for handling in-line
volumes to pass to the CSI plugins from `InlineCSIVolumeSource`. However a few fields
require special handling due to the absence of a PV. Specifically, reasonable
`MountOptions` and `AccessModes` need to be determined by plugin-specific APIs:
`GetAccessModeForVolume` and `GetMountOptions`.
The new VolumeAttachmentSource API will look as such: The new VolumeAttachmentSource API will look as such:
``` ```
@ -278,6 +294,8 @@ Node name. We are able to get all this information for Detach and WaitForAttach
by translating the in-tree inline volume source to a CSI volume source before by translating the in-tree inline volume source to a CSI volume source before
passing it to to the volume operations. passing it to to the volume operations.
The translation logic for inline volumes needs to set things up
There is currently a race condition in in-tree inline volumes where if a pod There is currently a race condition in in-tree inline volumes where if a pod
object is deleted and the ADC restarts we lose the information for the inline object is deleted and the ADC restarts we lose the information for the inline
volume and will not be able to detach the volume. This is a known issue and we volume and will not be able to detach the volume. This is a known issue and we