mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-27 00:30:18 +00:00
1b16db4ff6
The design for NFS-provising of volumes explains how the existing NFS CSI Node-Plugin can be used, and what the steps are to create the NFS-export with Ceph Mgr. Updates: #2913 Signed-off-by: Niels de Vos <ndevos@redhat.com>
71 lines
3.2 KiB
Markdown
71 lines
3.2 KiB
Markdown
# Dynamic provisioning of NFS volumes
|
|
|
|
Ceph has [support for NFS-Ganesha to export directories][ceph_mgr_nfs] on
|
|
CephFS. This can be used to export CephFS based volumes over NFS.
|
|
|
|
## Node-Plugin for mounting NFS-exports
|
|
|
|
The Kubernetes CSI community provides and maintains a [NFS CSI][nfs_csi]
|
|
driver. This driver can be used as a Node-Plugin so that NFS CSI volumes can be
|
|
mounted. When a CSI volume has the `server` and `share`
|
|
[parameters][nfs_csi_params], the Node-Plugin will be able to mount the
|
|
NFS-export.
|
|
|
|
## Exporting CephFS based volumes over NFS
|
|
|
|
Ceph-CSI already creates CephFS volumes, that can be mounted over the native
|
|
CephFS protocol. A new provisioner in Ceph-CSI can create CephFS volumes, and
|
|
include the required [NFS CSI parameters][nfs_csi_params] so that the [NFS CSI
|
|
driver][nfs_csi] can mount the CephFS volume over NFS.
|
|
|
|
The provisioner that handles the CSI requests for NFS volume can call the [Ceph
|
|
Mgr commands to export/unexport][ceph_mgr_nfs] the CephFS volumes. The CephFS
|
|
volumes would be internally managed by the NFS provisioner, and only be exposed
|
|
as NFS CSI volumes towards the consumers.
|
|
|
|
### `CreateVolume` CSI operation
|
|
|
|
When the Ceph-CSI NFS provisioner is requested to create a NFS CSI volume, the
|
|
following steps need to be taken:
|
|
|
|
1. create a CephFS volume, use the CephFS `CreateVolume` call or other internal
|
|
API
|
|
1. call the Ceph Mgr API to export the CephFS volume with NFS-Ganesha
|
|
1. return the NFS CSI volume, with `server` and `share` parameters (other
|
|
parameters that are useful for CephFS volume management may be kept)
|
|
|
|
The 2nd step requires a NFS-cluster name for the Ceph Mgr call(s). The name of
|
|
the NFS-cluster as managed by Ceph should be provided in the parameters of the
|
|
`CreateVolume` operation. For Kubernetes that means the parameters is set as an
|
|
option in the `StorageClass`.
|
|
|
|
The `server` parameter of the volume is an other option that is managed by the
|
|
Ceph (or Rook) infrastructure. This parameter is also required to be provided
|
|
in the `CreateVolume` parameters.
|
|
|
|
Removing the NFS-export for the volume (or other operations) requires the name
|
|
of the NFS-cluster, as it is needed for the Ceph Mgr API. Like other parameters
|
|
of the CephFS volume, it will be needed to store the NFS-cluster name in the
|
|
OMAP journalling.
|
|
|
|
### `DeleteVolume` CSI operation
|
|
|
|
The `DeleteVolume` operation only receives the `volume_id` parameter, which
|
|
is to be used by the CSI Controller (provisioner) to locate the backing volume.
|
|
The `DeleteVolume` operation for the CephFS provisioner already knows how to
|
|
delete volumes by ID.
|
|
|
|
In order to remove the exported volume from the NFS-cluster, the operation
|
|
needs to fetch the name of the NFS-cluster from the journal where it was stored
|
|
during `CreateVolume`.
|
|
|
|
### Additional CSI operations
|
|
|
|
`CreateVolume` and `DeleteVolume` are the only required operations for the CSI
|
|
Controller (provisioner). Additional features as they are supported by CephFS
|
|
can forward the operations to the CephFS provisioner at a later time.
|
|
|
|
[ceph_mgr_nfs]: https://docs.ceph.com/en/latest/mgr/nfs/
|
|
[nfs_csi]: https://github.com/kubernetes-csi/csi-driver-nfs
|
|
[nfs_csi_params]: https://github.com/kubernetes-csi/csi-driver-nfs/blob/master/docs/driver-parameters.md
|