CephFS Native driver

The CephFS Native driver enables the Shared File Systems service to export shared file systems to guests using the Ceph network protocol. Guests require a Ceph client in order to mount the file system.

Access is controlled via Ceph’s cephx authentication system. When a user requests share access for an ID, Ceph creates a corresponding Ceph auth ID and a secret key, if they do not already exist, and authorizes the ID to access the share. The client can then mount the share using the ID and the secret key.

To learn more about configuring Ceph clients to access the shares created using this driver, please see the Ceph documentation ( http://docs.ceph.com/docs/master/cephfs/). If you choose to use the kernel client rather than the FUSE client, the share size limits set in the Shared File Systems service may not be obeyed.

Supported shared file systems and operations

The driver supports CephFS shares.

The following operations are supported with CephFS back end:

• Create a share.

• Delete a share.

• Allow share access.

  • read-only access level is supported.

  • read-write access level is supported.

  Note the following limitation for CephFS shares:

  • Only cephx access type is supported.

• Deny share access.

• Create a snapshot.

• Delete a snapshot.

• Create a consistency group (CG).

• Delete a CG.

• Create a CG snapshot.

• Delete a CG snapshot.

Requirements

• Mitaka or later versions of manila.

• Jewel or later versions of Ceph.

• A Ceph cluster with a file system configured ( http://docs.ceph.com/docs/master/cephfs/createfs/)

• ceph-common package installed in the servers running the manila-share service.

• Ceph client installed in the guest, preferably the FUSE based client, ceph-fuse.

• Network connectivity between your Ceph cluster’s public network and the servers running the manila-share service.

• Network connectivity between your Ceph cluster’s public network and guests.

Important

A manila share backed onto CephFS is only as good as the underlying file system. Take care when configuring your Ceph cluster, and consult the latest guidance on the use of CephFS in the Ceph documentation ( http://docs.ceph.com/docs/master/cephfs/).

Authorize the driver to communicate with Ceph

Run the following commands to create a Ceph identity for the Shared File Systems service to use:

read -d '' MON_CAPS << EOF
allow r,
allow command "auth del",
allow command "auth caps",
allow command "auth get",
allow command "auth get-or-create"
EOF

ceph auth get-or-create client.manila -o manila.keyring \
mds 'allow *' \
osd 'allow rw' \
mgr 'allow r' \
mon "$MON_CAPS"

manila.keyring, along with your ceph.conf file, then needs to be placed on the server running the manila-share service.

Enable snapshots in Ceph if you want to use them in the Shared File Systems service:

ceph mds set allow_new_snaps true --yes-i-really-mean-it

In the server running the manila-share service, you can place the ceph.conf and manila.keyring files in the /etc/ceph directory. Set the same owner for the manila-share process and the manila.keyring file. Add the following section to the ceph.conf file.

[client.manila]
client mount uid = 0
client mount gid = 0
log file = /opt/stack/logs/ceph-client.manila.log
admin socket = /opt/stack/status/stack/ceph-$name.$pid.asok
keyring = /etc/ceph/manila.keyring

It is advisable to modify the Ceph client’s admin socket file and log file locations so that they are co-located with the Shared File Systems services’ pid files and log files respectively.

Configure CephFS back end in manila.conf

1. Add CephFS to enabled_share_protocols (enforced at the Shared File Systems service’s API layer). In this example we leave NFS and CIFS enabled, although you can remove these if you only use CephFS:

   enabled_share_protocols = NFS,CIFS,CEPHFS
   

2. Refer to the following table for the list of all the cephfs_native driver-specific configuration options.

   Description of CephFS share driver configuration options

   Configuration option = Default value	Description
   [DEFAULT]
   cephfs_auth_id = manila	(String) The name of the ceph auth identity to use.
   cephfs_cluster_name = None	(String) The name of the cluster in use, if it is not the default (‘ceph’).
   cephfs_conf_path =	(String) Fully qualified path to the ceph.conf file.

   Create a section to define a CephFS back end:

   [cephfs1]
   driver_handles_share_servers = False
   share_backend_name = CEPHFS1
   share_driver = manila.share.drivers.cephfs.cephfs_native.CephFSNativeDriver
   cephfs_conf_path = /etc/ceph/ceph.conf
   cephfs_auth_id = manila
   cephfs_cluster_name = ceph
   

   Also set the driver-handles-share-servers to False as the driver does not manage the lifecycle of share-servers.

3. Edit enabled_share_backends to point to the driver’s back-end section using the section name. In this example we are also including another back end (generic1), you would include whatever other back ends you have configured.

   enabled_share_backends = generic1,cephfs1
   

Creating shares

The default share type may have driver_handles_share_servers set to True. Configure a share type suitable for CephFS:

manila type-create cephfstype false

manila type-set cephfstype set share_backend_name='CEPHFS1'

Then create a share:

manila create --share-type cephfstype --name cephshare1 cephfs 1

Note the export location of the share:

manila share-export-location-list cephshare1

The export location of the share contains the Ceph monitor (mon) addresses and ports, and the path to be mounted. It is of the form, {mon ip addr:port}[,{mon ip addr:port}]:{path to be mounted}

Allowing access to shares

Allow Ceph auth ID alice access to the share using cephx access type.

manila access-allow cephshare1 cephx alice

Note the access status and the secret access key of alice.

manila access-list cephshare1

Mounting shares using FUSE client

Using the secret key of the authorized ID alice, create a keyring file alice.keyring.

[client.alice]
        key = AQA8+ANW/4ZWNRAAOtWJMFPEihBA1unFImJczA==

Using the monitor IP addresses from the share’s export location, create a configuration file, ceph.conf:

[client]
        client quota = true
        mon host = 192.168.1.7:6789, 192.168.1.8:6789, 192.168.1.9:6789

Finally, mount the file system, substituting the file names of the keyring and configuration files you just created, and substituting the path to be mounted from the share’s export location:

sudo ceph-fuse ~/mnt \
--id=alice \
--conf=./ceph.conf \
--keyring=./alice.keyring \
--client-mountpoint=/volumes/_nogroup/4c55ad20-9c55-4a5e-9233-8ac64566b98c

Known restrictions

Consider the driver as a building block for supporting multi-tenant workloads in the future. However, it can be used in private cloud deployments.

• The guests have direct access to Ceph’s public network.

• Snapshots are read-only. A user can read a snapshot’s contents from the .snap/{manila-snapshot-id}_{unknown-id} folder within the mounted share.

• To restrict share sizes, CephFS uses quotas that are enforced in the client side. The CephFS clients are relied on to respect quotas.

Security

• Each share’s data is mapped to a distinct Ceph RADOS namespace. A guest is restricted to access only that particular RADOS namespace.

• An additional level of resource isolation can be provided by mapping a share’s contents to a separate RADOS pool. This layout would be preferred only for cloud deployments with a limited number of shares needing strong resource separation. You can do this by setting a share type specification, cephfs:data_isolated for the share type used by the cephfs driver.

  manila type-key cephfstype set cephfs:data_isolated=True
  

• Untrusted manila guests pose security risks to the Ceph storage cluster as they would have direct access to the cluster’s public network.