Generic approach for share provisioning

The Manila Shared Filesystem Management Service can be configured to use Nova VMs and Cinder volumes. There are two modules that handle them in Manila: 1) ‘service_instance’ module creates VMs in Nova with predefined image called service image. This module can be used by any backend driver for provisioning of service VMs to be able to separate share resources among tenants. 2) ‘generic’ module operates with Cinder volumes and VMs created by ‘service_instance’ module, then creates shared filesystems based on volumes attached to VMs.

Network configurations

Each backend driver can handle networking in its own way, see: https://wiki.openstack.org/wiki/Manila/Networking

One of two possible configurations can be chosen for share provisioning
using ‘service_instance’ module:
  • Service VM has one net interface from net that is connected to public router. For successful creation of share, user network should be connected to public router too.
  • Service VM has two net interfaces, first one connected to service network, second one connected directly to user’s network.

Requirements for service image

  • Linux based distro

  • NFS server

  • Samba server >=3.2.0, that can be configured by data stored in registry

  • SSH server

  • Two net interfaces configured to DHCP (see network approaches)

  • ‘exportfs’ and ‘net conf’ libraries used for share actions

  • Following files will be used, so if their paths differ one needs to create at

    least symlinks for them:

    • /etc/exports (permanent file with NFS exports)
    • /var/lib/nfs/etab (temporary file with NFS exports used by ‘exportfs’)
    • /etc/fstab (permanent file with mounted filesystems)
    • /etc/mtab (temporary file with mounted filesystems used by ‘mount’)

Supported shared filesystems

  • NFS (access by IP)
  • CIFS (access by IP)

Known restrictions

  • One of Nova’s configurations only allows 26 shares per server. This limit comes from the maximum number of virtual PCI interfaces that are used for block device attaching. There are 28 virtual PCI interfaces, in this configuration, two of them are used for server needs and other 26 are used for attaching block devices that are used for shares.
  • Juno version works only with Neutron. Each share should be created with neutron-net and neutron-subnet IDs provided via share-network entity.
  • Juno version handles security group, flavor, image, keypair for Nova VM and also creates service networks, but does not use availability zones for Nova VMs and volume types for Cinder block devices.

The manila.share.drivers.generic Module

Generic Driver for shares.

class CIFSHelper(execute, ssh_execute, config_object)

Bases: manila.share.drivers.generic.NASHelperBase

Manage shares in samba server by net conf tool.

Class provides functionality to operate with CIFS shares. Samba server should be configured to use registry as configuration backend to allow dynamically share managements.

CIFSHelper.allow_access(server, share_name, access_type, access)

Add access for share.

CIFSHelper.create_export(server, share_name, recreate=False)

Create share at samba server.

CIFSHelper.deny_access(server, share_name, access_type, access, force=False)

Remove access for share.

CIFSHelper.init_helper(server)
CIFSHelper.remove_export(server, share_name)

Remove share definition from samba server.

class GenericShareDriver(db, *args, **kwargs)

Bases: manila.share.driver.ExecuteMixin, manila.share.driver.ShareDriver

Executes commands relating to Shares.

GenericShareDriver.allow_access(*args, **kwargs)
GenericShareDriver.check_for_setup_error()

Returns an error if prerequisites aren’t met.

GenericShareDriver.create_share(*args, **kwargs)
GenericShareDriver.create_share_from_snapshot(*args, **kwargs)
GenericShareDriver.create_snapshot(*args, **kwargs)
GenericShareDriver.delete_share(*args, **kwargs)
GenericShareDriver.delete_snapshot(*args, **kwargs)
GenericShareDriver.deny_access(*args, **kwargs)
GenericShareDriver.do_setup(context)

Any initialization the generic driver does while starting.

GenericShareDriver.ensure_share(*args, **kwargs)
GenericShareDriver.get_network_allocations_number()

Get number of network interfaces to be created.

GenericShareDriver.get_share_stats(refresh=False)

Get share status.

If ‘refresh’ is True, run update the stats first.

GenericShareDriver.setup_server(network_info, metadata=None)
GenericShareDriver.teardown_server(server_details, security_services=None)
class NASHelperBase(execute, ssh_execute, config_object)

Bases: object

Interface to work with share.

NASHelperBase.allow_access(server, share_name, access_type, access)

Allow access to the host.

NASHelperBase.create_export(server, share_name, recreate=False)

Create new export, delete old one if exists.

NASHelperBase.deny_access(local_path, share_name, access_type, access, force=False)

Deny access to the host.

NASHelperBase.init_helper(server)
NASHelperBase.remove_export(server, share_name)

Remove export.

class NFSHelper(execute, ssh_execute, config_object)

Bases: manila.share.drivers.generic.NASHelperBase

Interface to work with share.

NFSHelper.allow_access(*args, **kwargs)
NFSHelper.create_export(server, share_name, recreate=False)

Create new export, delete old one if exists.

NFSHelper.deny_access(*args, **kwargs)
NFSHelper.init_helper(server)
NFSHelper.remove_export(server, share_name)

Remove export.

ensure_server(f)
nfs_synchronized(f)

The manila.share.drivers.service_instance Module

Module for managing nova instances for share drivers.

class ServiceInstanceManager(db, *args, **kwargs)

Bases: object

Manages nova instances for various share drivers.

This class provides two external methods: 1. set_up_service_instance: creates instance and sets up share

infrastructure
  1. ensure_service_instance: ensure service instance is available.

  2. delete_service_instance: removes service instance and network

    infrastructure.

ServiceInstanceManager.delete_service_instance(context, instance_id, subnet_id, router_id)

Removes share infrastructure.

Deletes service vm and subnet, associated to share network.

ServiceInstanceManager.ensure_service_instance(context, server)

Ensures that server exists and active.

ServiceInstanceManager.get_config_option(key)

Returns value of config option.

Parameters:key – key of config’ option.
Returns:str – value of config’s option. first priority is driver’s config, second priority is global config.
ServiceInstanceManager.set_up_service_instance(context, instance_name, neutron_net_id, neutron_subnet_id)

Finds or creates and sets up service vm.

Parameters:
  • context – defines context, that should be used
  • instance_name – provides name for service VM
  • neutron_net_id – provides network id for service VM
  • neutron_subnet_id – provides subnet id for service VM
Returns:

dict with service instance details

Raises :

exception.ServiceInstanceException