diskimage-builder/diskimage_builder/block_device/level1/lvm.py
Yolanda Robla c2dc3dc78e LVM support for dib-block-device
This provides a basic LVM support to dib-block-device.

Co-Authored-By: Ian Wienand <iwienand@redhat.com>

Change-Id: Ibd624d9f95ee68b20a15891f639ddd5b3188cdf9
2017-08-24 16:22:56 +10:00

428 lines
14 KiB
Python

# Copyright 2017 Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import collections
import logging
import os
import tempfile
from diskimage_builder.block_device.exception \
import BlockDeviceSetupException
from diskimage_builder.block_device.plugin import NodeBase
from diskimage_builder.block_device.plugin import PluginBase
from diskimage_builder.block_device.utils import exec_sudo
logger = logging.getLogger(__name__)
#
# LVM
# ---
#
# The LVM config has three required keys; pvs, vgs and lvs
#
# lvm: -> LVSNode
# pvs: -> PvsNode
# lvs: -> LvsNode
# vgs: -> VgsNode
#
# The LVMPlugin will verify this and build nodes into the
# configuration graph.
#
# As described below, a LVSNode is created for synchronisation
# purposes. Thus if you had something like two partitions that became
# two physical-volumes (pv1 & pv2), that you then combine into a
# single volume group (vg) and then create several logical volumes
# (lv1, lv2, lv3) your graph would end up looking like:
#
# partition1 partition2
# | |
# ---> LVSNode <--+
# |
# +------+------+
# v v
# pv1 pv2
# | |
# +--> vg <---+
# |
# +-----+-----+
# v v v
# lv1 lv2 lv3
#
# After the create() call on the LVSNode object, the entire LVM setup
# would actually be complete. The other nodes are all just
# place-holders, and are used for further ordering (for example, the
# fs creation & mounting should depend on the logical volume nodes).
# For this reason, their create() calls are blank. However, for code
# organisational purposes they have a private _create() and _cleanup()
# call that is driven by the LVSNode object.
class PvsNode(NodeBase):
def __init__(self, name, state, base, options):
"""Physical volume
This is a placeholder node for the LVM physical volumes.
Arguments:
:param name: Name of this node
:param state: global state pointer
:param base: Parent partition
:param options: config options
"""
super(PvsNode, self).__init__(name, state)
self.base = base
self.options = options
def _create(self):
# the underlying device path of our parent was previously
# recorded into the state during blockdev creation; look it
# up.
phys_dev = self.state['blockdev'][self.base]['device']
cmd = ["pvcreate"]
cmd.append(phys_dev)
if self.options:
cmd.extend(self.options)
logger.debug("Creating pv command [%s]", cmd)
exec_sudo(cmd)
# save state
if 'pvs' not in self.state:
self.state['pvs'] = {}
self.state['pvs'][self.name] = {
'opts': self.options,
'device': phys_dev
}
def _cleanup(self):
exec_sudo(['pvremove', '--force',
self.state['pvs'][self.name]['device']])
def get_edges(self):
# See LVMNode.get_edges() for how this gets connected
return ([], [])
def create(self):
# see notes in LVMNode object
pass
class VgsNode(NodeBase):
def __init__(self, name, state, base, options):
"""Volume Group
This is a placeholder node for a volume group
Arguments:
:param name: Name of this node
:param state: global state pointer
:param base: Parent :class:`PvsNodes` this volume group exists on
:param options: extra options passed to the `vgcreate` command
"""
super(VgsNode, self).__init__(name, state)
self.base = base
self.options = options
def _create(self):
# The PV's have saved their actual device name into the state
# during their _create(). Look at our base elements and thus
# find the underlying device paths in the state.
pvs_devs = []
for pv in self.base:
pvs_dev = self.state['pvs'][pv]['device']
pvs_devs.append(pvs_dev)
cmd = ["vgcreate", ]
cmd.append(self.name)
cmd.extend(pvs_devs)
if self.options:
cmd.extend(self.options)
logger.debug("Creating vg command [%s]", cmd)
exec_sudo(cmd)
# save state
if 'vgs' not in self.state:
self.state['vgs'] = {}
self.state['vgs'][self.name] = {
'opts': self.options,
'devices': self.base,
}
def _cleanup(self):
exec_sudo(['vgchange', '-an', self.name])
exec_sudo(['vgremove', '--force', self.name])
def get_edges(self):
# self.base is already a list, per the config. There might be
# multiple pv parents here.
edge_from = self.base
edge_to = []
return (edge_from, edge_to)
def create(self):
# see notes in LVMNode object
pass
class LvsNode(NodeBase):
def __init__(self, name, state, base, options, size, extents):
"""Logical Volume
This is a placeholder node for a logical volume
Arguments:
:param name: Name of this node
:param state: global state pointer
:param base: the parent volume group
:param options: options passed to lvcreate
:param size: size of the LV, in MB (this or extents must be provided)
:param extents: size of the LV in extents
"""
super(LvsNode, self).__init__(name, state)
self.base = base
self.options = options
self.size = size
self.extents = extents
def _create(self):
cmd = ["lvcreate", ]
cmd.extend(['--name', self.name])
if self.size:
cmd.extend(['-L', self.size])
elif self.extents:
cmd.extend(['-l', self.extents])
if self.options:
cmd.extend(self.options)
cmd.append(self.base)
logger.debug("Creating lv command [%s]", cmd)
exec_sudo(cmd)
# save state
self.state['blockdev'][self.name] = {
'vgs': self.base,
'size': self.size,
'extents': self.extents,
'opts': self.options,
'device': '/dev/mapper/%s-%s' % (self.base, self.name)
}
def _cleanup(self):
exec_sudo(['lvchange', '-an',
'/dev/%s/%s' % (self.base, self.name)])
exec_sudo(['lvremove', '--force',
'/dev/%s/%s' % (self.base, self.name)])
def get_edges(self):
edge_from = [self.base]
edge_to = []
return (edge_from, edge_to)
def create(self):
# see notes in LVMNode object
pass
class LVMNode(NodeBase):
def __init__(self, name, state, pvs, lvs, vgs):
"""LVM Driver Node
This is the "global" node where all LVM operations are driven
from. In the node graph, the LVM physical-volumes depend on
this node. This node then depends on the devices that the
PV's require. This node incorporates *all* LVM setup;
i.e. after the create() call here we have created all pv's,
lv's and vg. The <Pvs|Lvs|Vgs>Node objects in the graph are
therefore just dependency place holders whose create() call
does nothing.
This is quite important in the cleanup phase. In theory, you
would remove the vg's, then the lv's and then free-up the
pv's. But the process of removing these also removes them
from the LVM meta-data in the image, undoing all the
configuration. Thus the unwind process is also "atomic" in
this node; we do a copy of the devices before removing the LVM
components, and then copy them back (better ideas welcome!)
As with creation, the cleanup() calls in the other nodes are
just placeholders.
Arguments:
:param name: name of this node
:param state: global state pointer
:param pvs: A list of :class:`PvsNode` objects
:param lvs: A list of :class:`LvsNode` objects
:param vgs: A list of :class:`VgsNode` objects
"""
super(LVMNode, self).__init__(name, state)
self.pvs = pvs
self.lvs = lvs
self.vgs = vgs
def get_edges(self):
# This node requires the physical device(s), which is
# recorded in the "base" argument of the PV nodes.
pvs = []
for pv in self.pvs:
pvs.append(pv.base)
edge_from = set(pvs)
# The PV nodes should then depend on us. i.e., we just made
# this node a synchronisation point
edge_to = [pv.name for pv in self.pvs]
return (edge_from, edge_to)
def create(self):
# Run through pvs->vgs->lvs and create them
# XXX: we could theoretically get this same info from walking
# the graph of our children nodes? Would that be helpful in
# any way?
for pvs in self.pvs:
pvs._create()
for vgs in self.vgs:
vgs._create()
for lvs in self.lvs:
lvs._create()
def cleanup(self):
# First do a copy of all physical devices to individual
# temporary files. This is because the physical device is
# full of LVM metadata describing the volumes and we don't
# have a better way to handle removing the devices/volumes
# from the host system while persisting this metadata in the
# underlying devices.
tempfiles = collections.OrderedDict() # to unwind in same order!
for pvs in self.pvs:
phys_dev = self.state['blockdev'][pvs.base]['device']
target_file = tempfile.NamedTemporaryFile(delete=False)
target_file.close()
exec_sudo(['dd', 'if=%s' % phys_dev,
'of=%s' % target_file.name])
tempfiles[target_file.name] = phys_dev
# once copied, start the removal in reverse order
for lvs in self.lvs:
lvs._cleanup()
for vgs in self.vgs:
vgs._cleanup()
for pvs in self.pvs:
pvs._cleanup()
exec_sudo(['udevadm', 'settle'])
# after the cleanup copy devices back
for tmp_name, phys_dev in tempfiles.items():
exec_sudo(['dd', 'if=%s' % tmp_name, 'of=%s' % phys_dev])
os.unlink(tmp_name)
class LVMPlugin(PluginBase):
def _config_error(self, msg):
raise BlockDeviceSetupException(msg)
def __init__(self, config, defaults, state):
"""Build LVM nodes
This reads the "lvm:" config stanza, validates it and produces
the PV, VG and LV nodes. These are all synchronised via a
LVMNode as described above.
Arguments:
:param config: "lvm" configuration dictionary
:param defaults: global defaults dictionary
:param state: global state reference
"""
super(LVMPlugin, self).__init__()
# note lvm: doesn't require a base ... the base is the
# physical devices the "pvs" nodes are made on.
if 'name' not in config:
self._config_error("Lvm config requires 'name'")
if 'pvs' not in config:
self._config_error("Lvm config requires a 'pvs'")
if 'vgs' not in config:
self._config_error("Lvm config needs 'vgs'")
if 'lvs' not in config:
self._config_error("Lvm config needs 'lvs'")
# create physical volume nodes
self.pvs = []
self.pvs_keys = []
for pvs_cfg in config['pvs']:
if 'name' not in pvs_cfg:
self._config_error("Missing 'name' in pvs config")
if 'base' not in pvs_cfg:
self._config_error("Missing 'base' in pvs_config")
pvs_item = PvsNode(pvs_cfg['name'], state,
pvs_cfg['base'],
pvs_cfg.get('options'))
self.pvs.append(pvs_item)
# create volume group nodes
self.vgs = []
self.vgs_keys = []
for vgs_cfg in config['vgs']:
if 'name' not in vgs_cfg:
self._config_error("Missing 'name' in vgs config")
if 'base' not in vgs_cfg:
self._config_error("Missing 'base' in vgs config")
# Ensure we have a valid PVs backing this VG
for pvs in vgs_cfg['base']:
if not any(pv.name == pvs for pv in self.pvs):
self._config_error("base:%s in vgs does not "
"match a valid pvs" % pvs)
vgs_item = VgsNode(vgs_cfg['name'], state, vgs_cfg['base'],
vgs_cfg.get('options', None))
self.vgs.append(vgs_item)
# create logical volume nodes
self.lvs = []
for lvs_cfg in config['lvs']:
if 'name' not in lvs_cfg:
self._config_error("Missing 'name' in lvs config")
if 'base' not in lvs_cfg:
self._config_error("Missing 'base' in lvs config")
if 'size' not in lvs_cfg and 'extents' not in lvs_cfg:
self._config_error("Missing 'size' or 'extents' in lvs config")
# ensure this logical volume has a valid volume group base
if not any(vg.name == lvs_cfg['base'] for vg in self.vgs):
self._config_error("base:%s in lvs does not match a valid vg" %
lvs_cfg['base'])
lvs_item = LvsNode(lvs_cfg['name'], state, lvs_cfg['base'],
lvs_cfg.get('options', None),
lvs_cfg.get('size', None),
lvs_cfg.get('extents', None))
self.lvs.append(lvs_item)
# create the "driver" node
self.lvm_node = LVMNode(config['name'], state,
self.pvs, self.lvs, self.vgs)
def get_nodes(self):
# the nodes for insertion into the graph are all of the pvs,
# vgs and lvs nodes we have created above, and the root node.
return self.pvs + self.vgs + self.lvs + [self.lvm_node]