diff options
Diffstat (limited to 'contributors')
| -rw-r--r-- | contributors/design-proposals/storage/csi-migration.md | 68 |
1 files changed, 28 insertions, 40 deletions
diff --git a/contributors/design-proposals/storage/csi-migration.md b/contributors/design-proposals/storage/csi-migration.md index 1b96b9ad..327f3e8c 100644 --- a/contributors/design-proposals/storage/csi-migration.md +++ b/contributors/design-proposals/storage/csi-migration.md @@ -179,10 +179,9 @@ type CSITranslator interface { // by the `Driver` field in the CSI Source. The input PV object will not be modified. 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) { + // TranslateInTreeInlineVolumeToPVSpec takes an inline intree volume and will translate + // the in-tree volume source to a PersistentVolumeSpec containing a CSIPersistentVolumeSource + TranslateInTreeInlineVolumeToPVSpec(volume *v1.Volume) (*v1.PersistentVolumeSpec, error) { // IsMigratableByName tests whether there is Migration logic for the in-tree plugin // for the given `pluginName` @@ -191,12 +190,6 @@ type CSITranslator interface { // GetCSINameFromIntreeName maps the name of a CSI driver to its in-tree version GetCSINameFromIntreeName(pluginName string) (string, error) { - // GetAccessModes returns a default access mode based on the plugin and volume spec - GetAccessModes(pluginName string, vol *v1.Volume) (csi.VolumeCapability_AccessMode, error) { - - // GetMountOptions returns a default mount option based on the plugin and volume spec - GetMountOptions(pluginName string, vol *v1.Volume) (string) { - // IsPVMigratable tests whether there is Migration logic for the given Persistent Volume IsPVMigratable(pv *v1.PersistentVolume) bool { @@ -244,54 +237,49 @@ with the in-tree plugin, the VolumeAttachment object becomes orphaned. ### In-line Volumes -In-line controller calls are a special case because there is no PV. In this case -we will translate the in-line volume source into a CSIPersistentVolumeSource -and copy it to the field `VolumeAttachment.Spec.Source.VolumeAttachmentSource.InlineCSIVolumeSource`. -The VolumeAttachment name must be made with the CSI Translated version of the +In-line controller calls are a special case because there is no PV. In this case, +we will translate the in-line Volume into a PersistentVolumeSpec using +plugin-specific translation logic in the CSI translation library method, +`TranslateInTreeInlineVolumeToPVSpec`. The resulting PersistentVolumeSpec will +and be stored in a new field `VolumeAttachment.Spec.Source.VolumeAttachmentSource.InlineVolumeSpec`. + +The plugin-specific CSI translation logic invoked by `TranslateInTreeInlineVolumeToPVSpec` +will need to populate the `CSIPersistentVolumeSource` field along with appropriate +values for `AccessModes` and `MountOptions` fields in +`VolumeAttachment.Spec.Source.VolumeAttachmentSource.InlineVolumeSpec`. Since +`AccessModes` and `MountOptions` are not specified for inline volumes, default values +for these fields suitable for the CSI plugin will need to be populated in addition +to translation logic to populate `CSIPersistentVolumeSource`. + +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 (described in more detail below). -The CSI Attacher will have to be modified to also check for `InlineCSIVolumeSource` -besides the `PersistentVolumeName`. Only one of the two may be specified. If `PersistentVolumeName` -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 +The CSI Attacher will have to be modified to also check for `InlineVolumeSpec` +besides the `PersistentVolumeName`. Only one of the two may be specified. If `PersistentVolumeName` +is empty and `InlineVolumeSpec` 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 attachment (through the CSI plugins) from `InlineCSIVolumeSource`. However -a few fields require special handling due to the absence of a PV where such fields -are assigned desired values. Specifically, reasonable `MountOptions` and -`AccessModes` settings need to be determined by plugin-specific APIs: -`GetMountOptions` and `GetAccessModes` that sets the default values for -these parameters and satisfies the broadest of scenarios supported by the CSI -plugin. Some specific example: -1. If GCEPersistentDiskVolumeSource.ReadOnly is true, `GetAccessModes` for GCE PD -can return csi.VolumeCapability_AccessMode_MULTI_NODE_READER_ONLY. If -If GCEPersistentDiskVolumeSource.ReadOnly is false, `GetAccessModes` for GCE PD -can return csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER -2. The EBS CSI driver only supports csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER -today . So `GetAccessModes` for EBS can always return -csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER until further modes are supported. -3. For shared FS plugins like AzureFile or CephFS, `GetAccessModes` may return -csi.VolumeCapability_AccessMode_MULTI_NODE_MULTI_WRITER +The CSI Attacher will have access to all the data it requires for handling in-line +volumes attachment (through the CSI plugins) from fields in the `InlineVolumeSpec`. The new VolumeAttachmentSource API will look as such: ``` // VolumeAttachmentSource represents a volume that should be attached. -// Right now only PersistenVolumes can be attached via external attacher, -// in future we may allow also inline volumes in pods. +// Inline volumes and Persistent volumes can be attached via external attacher. // Exactly one member can be set. type VolumeAttachmentSource struct { // Name of the persistent volume to attach. // +optional PersistentVolumeName *string `json:"persistentVolumeName,omitempty" protobuf:"bytes,1,opt,name=persistentVolumeName"` - // Translated VolumeSource from a pod to a CSIPersistentVolumeSource - // to support shimming of in-tree inline volumes to a CSI backend. + // A PersistentVolumeSpec whose fields contain translated data from a pod's inline + // VolumeSource to support shimming of in-tree inline volumes to a CSI backend. // This field is alpha-level and is only honored by servers that // enable the CSIMigration feature. // +optional - InlineCSIVolumeSource *v1.CSIPersistentVolumeSource `json:"inlineCSIVolumeSource,omitempty" protobuf:"bytes,2,opt,name=inlineCSIVolumeSource"` + InlineVolumeSpec *v1.PersistentVolumeSpec `json:"inlineVolumeSpec,omitempty" protobuf:"bytes,2,opt,name=inlineVolumeSpec"` } ``` |