Config option for share_backend_name

It is currently not possible to set a specific share backend name as config option. "cephfsnfs1" is hardcoded in the template. It is thereforce also not possible to register additional ganesha charms on different backends.

Below the result of 2 ganesha charms on different ceph clusters.

+----------------------------------+----------------+------------+--------+
| Name | Host | Backend | Pool |
+----------------------------------+----------------+------------+--------+
| 10.110.100.201@cephfsnfs1#cephfs | 10.110.100.201 | cephfsnfs1 | cephfs |
| 10.110.100.202@cephfsnfs1#cephfs | 10.110.100.202 | cephfsnfs1 | cephfs |
+----------------------------------+----------------+------------+--------+

All registered to cephfsnfs1 backend. It should be possible to set it to a another backend.

I changed the template [/var/lib/juju/agents/unit-manila-ganesha-sc2-[n]/charm/templates/rocky] for a test on all nodes as follows:

...
enabled_share_backends = cephfsnfs2
...
[cephfsnfs2]
driver_handles_share_servers = False
ganesha_rados_store_enable = True
ganesha_rados_store_pool_name = {{ options.application_name }}
share_backend_name = CEPHFSNFS2
share_driver = manila.share.drivers.cephfs.driver.CephFSDriver
cephfs_protocol_helper_type = NFS
cephfs_conf_path = /etc/ceph/ceph.conf
cephfs_auth_id = {{ options.application_name }}
cephfs_cluster_name = ceph
cephfs_enable_snapshots = False
cephfs_ganesha_server_is_remote = False
cephfs_ganesha_server_ip = {{ options.access_ip }}
...

juju run --application manila-ganesha-sc2 ./hooks/config-changed
juju run-action --wait manila/leader restart-services

Now it works as expected.

+----------------------------------+----------------+------------+--------+
| Name | Host | Backend | Pool |
+----------------------------------+----------------+------------+--------+
| 10.110.100.201@cephfsnfs1#cephfs | 10.110.100.201 | cephfsnfs1 | cephfs |
| 10.110.100.202@cephfsnfs2#cephfs | 10.110.100.202 | cephfsnfs2 | cephfs |
+----------------------------------+----------------+------------+--------+