def Grow(self, amount, dryrun, backingstore, excl_stor):
"""Grow the Volume.
@type amount: integer
@param amount: the amount (in mebibytes) to grow with
@type dryrun: boolean
@param dryrun: whether to execute the operation in simulation mode
only, without actually increasing the size
"""
if not backingstore:
return
if not self.Attach():
base.ThrowError("Can't attach to rbd device during Grow()")
if dryrun:
# the rbd tool does not support dry runs of resize operations.
# Since rbd volumes are thinly provisioned, we assume
# there is always enough free space for the operation.
return
rbd_pool = self.params[constants.LDP_POOL]
rbd_name = self.unique_id[1]
new_size = self.size + amount
# Resize the rbd volume (Image) inside the RADOS cluster.
cmd = self.__class__.MakeRbdCmd(self.params, ["resize", "-p", rbd_pool,
rbd_name, "--size",
"%s" % new_size])
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("rbd resize failed (%s): %s",
result.fail_reason, result.output)
def _AssembleLocal(self, minor, backend, meta, size):
"""Configure the local part of a DRBD device.
@type minor: int
@param minor: the minor to assemble locally
@type backend: string
@param backend: path to the data device to use
@type meta: string
@param meta: path to the meta device to use
@type size: int
@param size: size in MiB
"""
cmds = self._cmd_gen.GenLocalInitCmds(minor, backend, meta,
size, self.params)
for cmd in cmds:
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("drbd%d: can't attach local disk: %s",
minor, result.output)
# syncer init only for drbd => 8.4 - in 8.4 it must be set after local, not in net
info = DRBD8.GetProcInfo()
version = info.GetVersion()
if version["k_minor"] >= 4:
sync_errors = self._SetMinorSyncParams(minor, self.params)
# try second time because disk config for drbd resource may be still uninitialized
if sync_errors:
time.sleep(1)
sync_errors = self._SetMinorSyncParams(minor, self.params)
if sync_errors:
base.ThrowError("drbd%d: can't set the synchronization parameters: %s" %
(minor, utils.CommaJoin(sync_errors)))
def AttachNet(self, multimaster):
"""Reconnects the network.
This method connects the network side of the device with a
specified multi-master flag. The device needs to be 'Standalone'
but have valid network configuration data.
@type multimaster: boolean
@param multimaster: init the network in dual-primary mode
"""
if self.minor is None:
base.ThrowError("drbd%d: device not attached in AttachNet",
self._aminor)
if None in (self._lhost, self._lport, self._rhost, self._rport):
base.ThrowError("drbd%d: missing network info in AttachNet()",
self.minor)
status = self.GetProcStatus()
if not status.is_standalone:
base.ThrowError("drbd%d: device is not standalone in AttachNet",
self.minor)
self._AssembleNet(self.minor,
(self._lhost, self._lport, self._rhost, self._rport),
dual_pri=multimaster,
hmac=constants.DRBD_HMAC_ALG,
secret=self._secret)
def _ParseLvInfoLine(cls, line, sep):
"""Parse one line of the lvs output used in L{_GetLvInfo}.
"""
elems = line.strip().split(sep)
# The previous iteration of code here assumed that LVM might put another
# separator to the right of the output. The PV info might be empty for
# thin volumes, so stripping off the separators might cut off the last
# empty element - do this instead.
if len(elems) == 7 and elems[-1] == "":
elems.pop()
if len(elems) != 6:
base.ThrowError("Can't parse LVS output, len(%s) != 6", str(elems))
(status, major, minor, pe_size, stripes, pvs) = elems
if len(status) < 6:
base.ThrowError("lvs lv_attr is not at least 6 characters (%s)", status)
try:
major = int(major)
minor = int(minor)
except (TypeError, ValueError), err:
base.ThrowError("lvs major/minor cannot be parsed: %s", str(err))
def Snapshot(self, snap_name=None, snap_size=None):
"""Create a snapshot copy of an lvm block device.
@returns: tuple (vg, lv)
"""
if not snap_name:
snap_name = self._lv_name + ".snap"
if not snap_size:
# FIXME: choose a saner value for the snapshot size
# let's stay on the safe side and ask for the full size, for now
snap_size = self.size
# remove existing snapshot if found
snap = LogicalVolume((self._vg_name, snap_name), None, snap_size,
self.params, self.dyn_params)
base.IgnoreError(snap.Remove)
vg_info = self.GetVGInfo([self._vg_name], False)
if not vg_info:
base.ThrowError("Can't compute VG info for vg %s", self._vg_name)
free_size, _, _ = vg_info[0]
if free_size < snap_size:
base.ThrowError("Not enough free space: required %s,"
" available %s", snap_size, free_size)
_CheckResult(utils.RunCmd(["lvcreate", "-L%dm" % snap_size, "-s",
"-n%s" % snap_name, self.dev_path]))
return (self._vg_name, snap_name)
def _AssembleLocal(self, minor, backend, meta, size):
"""Configure the local part of a DRBD device.
@type minor: int
@param minor: the minor to assemble locally
@type backend: string
@param backend: path to the data device to use
@type meta: string
@param meta: path to the meta device to use
@type size: int
@param size: size in MiB
"""
cmds = self._cmd_gen.GenLocalInitCmds(minor, backend, meta,
size, self.params)
for cmd in cmds:
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("drbd%d: can't attach local disk: %s",
minor, result.output)
def _WaitForMinorSyncParams():
"""Call _SetMinorSyncParams and raise RetryAgain on errors.
"""
if self._SetMinorSyncParams(minor, self.params):
raise utils.RetryAgain()
if self._NeedsLocalSyncerParams():
# Retry because disk config for DRBD resource may be still uninitialized.
try:
utils.Retry(_WaitForMinorSyncParams, 1.0, 5.0)
except utils.RetryTimeout as e:
base.ThrowError("drbd%d: can't set the synchronization parameters: %s" %
(minor, utils.CommaJoin(e.args[0])))
def _MapVolumeToBlockdev(self, unique_id):
"""Maps existing rbd volumes to block devices.
This method should be idempotent if the mapping already exists.
@rtype: string
@return: the block device path that corresponds to the volume
"""
pool = self.params[constants.LDP_POOL]
name = unique_id[1]
# Check if the mapping already exists.
rbd_dev = self._VolumeToBlockdev(pool, name)
if rbd_dev:
# The mapping exists. Return it.
return rbd_dev
# The mapping doesn't exist. Create it.
map_cmd = self.__class__.MakeRbdCmd(self.params, ["map", "-p", pool, name])
result = utils.RunCmd(map_cmd)
if result.failed:
base.ThrowError("rbd map failed (%s): %s",
result.fail_reason, result.output)
# Find the corresponding rbd device.
rbd_dev = self._VolumeToBlockdev(pool, name)
if not rbd_dev:
base.ThrowError("rbd map succeeded, but could not find the rbd block"
" device in output of showmapped, for volume: %s", name)
# The device was successfully mapped. Return it.
return rbd_dev
def RemoveChildren(self, devices):
"""Detach the drbd device from local storage.
@type devices: list of L{BlockDev}
@param devices: a list of exactly two L{BlockDev} objects; the first
denotes the data device, the second the meta device for this DRBD device
"""
if self.minor is None:
base.ThrowError(
"drbd%d: can't attach to drbd8 during RemoveChildren",
self._aminor)
# early return if we don't actually have backing storage
info = self._GetShowInfo(self.minor)
if "local_dev" not in info:
return
if len(self._children) != 2:
base.ThrowError("drbd%d: we don't have two children: %s",
self.minor, self._children)
if self._children.count(
None) == 2: # we don't actually have children :)
logging.warning("drbd%d: requested detach while detached",
self.minor)
return
if len(devices) != 2:
base.ThrowError("drbd%d: we need two children in RemoveChildren",
self.minor)
for child, dev in zip(self._children, devices):
if dev != child.dev_path:
base.ThrowError(
"drbd%d: mismatch in local storage (%s != %s) in"
" RemoveChildren", self.minor, dev, child.dev_path)
self._ShutdownLocal(self.minor)
self._children = []
def Grow(self, amount, dryrun, backingstore, _excl_stor):
"""Grow the file
@param amount: the amount (in mebibytes) to grow by.
"""
# Check that the file exists
self.Exists(assert_exists=True)
if amount < 0:
base.ThrowError("%s: can't grow by negative amount", self.path)
if dryrun:
return
if not backingstore:
return
current_size = self.Size()
new_size = current_size + amount * 1024 * 1024
try:
f = open(self.path, "a+")
f.truncate(new_size)
f.close()
except EnvironmentError, err:
base.ThrowError("%s: can't grow: ", self.path, str(err))
def _InitMeta(cls, minor, dev_path):
"""Initialize a meta device.
This will not work if the given minor is in use.
@type minor: int
@param minor: the DRBD minor whose (future) meta device should be
initialized
@type dev_path: string
@param dev_path: path to the meta device to initialize
"""
# Zero the metadata first, in order to make sure drbdmeta doesn't
# try to auto-detect existing filesystems or similar (see
# http://code.google.com/p/ganeti/issues/detail?id=182); we only
# care about the first 128MB of data in the device, even though it
# can be bigger
result = utils.RunCmd([
constants.DD_CMD, "if=/dev/zero",
"of=%s" % dev_path,
"bs=%s" % constants.DD_BLOCK_SIZE, "count=128", "oflag=direct"
])
if result.failed:
base.ThrowError("Can't wipe the meta device: %s", result.output)
info = DRBD8.GetProcInfo()
cmd_gen = DRBD8.GetCmdGenerator(info)
cmd = cmd_gen.GenInitMetaCmd(minor, dev_path)
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("Can't initialize meta device: %s", result.output)
def _CheckMetaSize(meta_device):
"""Check if the given meta device looks like a valid one.
This currently only checks the size, which must be around
128MiB.
@type meta_device: string
@param meta_device: the path to the device to check
"""
result = utils.RunCmd(["blockdev", "--getsize", meta_device])
if result.failed:
base.ThrowError("Failed to get device size: %s - %s",
result.fail_reason, result.output)
try:
sectors = int(result.stdout)
except (TypeError, ValueError):
base.ThrowError("Invalid output from blockdev: '%s'",
result.stdout)
num_bytes = sectors * 512
if num_bytes < 128 * 1024 * 1024: # less than 128MiB
base.ThrowError("Meta device too small (%.2fMib)",
(num_bytes / 1024 / 1024))
# the maximum *valid* size of the meta device when living on top
# of LVM is hard to compute: it depends on the number of stripes
# and the PE size; e.g. a 2-stripe, 64MB PE will result in a 128MB
# (normal size), but an eight-stripe 128MB PE will result in a 1GB
# size meta device; as such, we restrict it to 1GB (a little bit
# too generous, but making assumptions about PE size is hard)
if num_bytes > 1024 * 1024 * 1024:
base.ThrowError("Meta device too big (%.2fMiB)",
(num_bytes / 1024 / 1024))
def AddChildren(self, devices):
"""Add a disk to the DRBD device.
@type devices: list of L{BlockDev}
@param devices: a list of exactly two L{BlockDev} objects; the first
denotes the data device, the second the meta device for this DRBD device
"""
if self.minor is None:
base.ThrowError("drbd%d: can't attach to dbrd8 during AddChildren",
self._aminor)
if len(devices) != 2:
base.ThrowError("drbd%d: need two devices for AddChildren",
self.minor)
info = self._GetShowInfo(self.minor)
if "local_dev" in info:
base.ThrowError("drbd%d: already attached to a local disk",
self.minor)
backend, meta = devices
if backend.dev_path is None or meta.dev_path is None:
base.ThrowError("drbd%d: children not ready during AddChildren",
self.minor)
backend.Open()
meta.Open()
self._CheckMetaSize(meta.dev_path)
self._InitMeta(DRBD8.FindUnusedMinor(), meta.dev_path)
self._AssembleLocal(self.minor, backend.dev_path, meta.dev_path,
self.size)
self._children = devices
def _GetLvInfo(cls, dev_path, _run_cmd=utils.RunCmd):
"""Get info about the given existing LV to be used.
"""
sep = "|"
result = _run_cmd(["lvs", "--noheadings", "--separator=%s" % sep,
"--units=k", "--nosuffix",
"-olv_attr,lv_kernel_major,lv_kernel_minor,"
"vg_extent_size,stripes,devices", dev_path])
if result.failed:
base.ThrowError("Can't find LV %s: %s, %s",
dev_path, result.fail_reason, result.output)
# the output can (and will) have multiple lines for multi-segment
# LVs, as the 'stripes' parameter is a segment one, so we take
# only the last entry, which is the one we're interested in; note
# that with LVM2 anyway the 'stripes' value must be constant
# across segments, so this is a no-op actually
out = result.stdout.splitlines()
if not out: # totally empty result? splitlines() returns at least
# one line for any non-empty string
base.ThrowError("Can't parse LVS output, no lines? Got '%s'", str(out))
pv_names = set()
for line in out:
(status, major, minor, pe_size, stripes, more_pvs) = \
cls._ParseLvInfoLine(line, sep)
pv_names.update(more_pvs)
return (status, major, minor, pe_size, stripes, pv_names)
def CreateFromFile(filename=constants.DRBD_STATUS_FILE):
try:
lines = utils.ReadFile(filename).splitlines()
except EnvironmentError, err:
if err.errno == errno.ENOENT:
base.ThrowError("The file %s cannot be opened, check if the module"
" is loaded (%s)", filename, str(err))
else:
base.ThrowError("Can't read the DRBD proc file %s: %s",
filename, str(err))
def _ParseRbdShowmappedPlain(output, volume_name):
"""Parse the (plain / text) output of `rbd showmapped'.
This method parses the output of `rbd showmapped' and returns
the rbd block device path (e.g. /dev/rbd0) that matches the
given rbd volume.
@type output: string
@param output: the plain text output of `rbd showmapped'
@type volume_name: string
@param volume_name: the name of the volume whose device we search for
@rtype: string or None
@return: block device path if the volume is mapped, else None
"""
allfields = 5
volumefield = 2
devicefield = 4
lines = output.splitlines()
# Try parsing the new output format (ceph >= 0.55).
splitted_lines = map(lambda l: l.split(), lines)
# Check for empty output.
if not splitted_lines:
return None
# Check showmapped output, to determine number of fields.
field_cnt = len(splitted_lines[0])
if field_cnt != allfields:
# Parsing the new format failed. Fallback to parsing the old output
# format (< 0.55).
splitted_lines = map(lambda l: l.split("\t"), lines)
if field_cnt != allfields:
base.ThrowError(
"Cannot parse rbd showmapped output expected %s fields,"
" found %s", allfields, field_cnt)
matched_lines = \
filter(lambda l: len(l) == allfields and l[volumefield] == volume_name,
splitted_lines)
if len(matched_lines) > 1:
base.ThrowError("rbd volume %s mapped more than once", volume_name)
if matched_lines:
# rbd block device found. Return it.
rbd_dev = matched_lines[0][devicefield]
return rbd_dev
# The given volume is not mapped.
return None
def _GetNetFamily(minor, lhost, rhost):
if netutils.IP6Address.IsValid(lhost):
if not netutils.IP6Address.IsValid(rhost):
base.ThrowError("drbd%d: can't connect ip %s to ip %s" %
(minor, lhost, rhost))
return "ipv6"
elif netutils.IP4Address.IsValid(lhost):
if not netutils.IP4Address.IsValid(rhost):
base.ThrowError("drbd%d: can't connect ip %s to ip %s" %
(minor, lhost, rhost))
return "ipv4"
else:
base.ThrowError("drbd%d: Invalid ip %s" % (minor, lhost))
def Close(self):
"""Make the local state secondary.
This will, of course, fail if the device is in use.
"""
if self.minor is None and not self.Attach():
base.ThrowError("drbd%d: can't Attach() in Close()", self._aminor)
cmd = self._cmd_gen.GenSecondaryCmd(self.minor)
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("drbd%d: can't switch drbd device to secondary: %s",
self.minor, result.output)
def GetProcStatus(self):
"""Return the current status data from /proc/drbd for this device.
@rtype: DRBD8Status
"""
if self.minor is None:
base.ThrowError("drbd%d: GetStats() called while not attached",
self._aminor)
info = DRBD8.GetProcInfo()
if not info.HasMinorStatus(self.minor):
base.ThrowError("drbd%d: can't find myself in /proc", self.minor)
return info.GetMinorStatus(self.minor)
class DRBD8(object):
"""Various methods to deals with the DRBD system as a whole.
This class provides a set of methods to deal with the DRBD installation on
the node or with uninitialized devices as opposed to a DRBD device.
"""
_USERMODE_HELPER_FILE = "/sys/module/drbd/parameters/usermode_helper"
_MAX_MINORS = 255
@staticmethod
def GetUsermodeHelper(filename=_USERMODE_HELPER_FILE):
"""Returns DRBD usermode_helper currently set.
@type filename: string
@param filename: the filename to read the usermode helper from
@rtype: string
@return: the currently configured DRBD usermode helper
"""
try:
helper = utils.ReadFile(filename).splitlines()[0]
except EnvironmentError, err:
if err.errno == errno.ENOENT:
base.ThrowError(
"The file %s cannot be opened, check if the module"
" is loaded (%s)", filename, str(err))
else:
base.ThrowError("Can't read DRBD helper file %s: %s", filename,
str(err))
if not helper:
base.ThrowError("Can't read any data from %s", filename)
return helper
def __init__(self, unique_id, children, size, params, dyn_params, *args):
"""Initalizes a file device backend.
"""
if children:
base.ThrowError("Invalid setup for file device")
try:
driver, path = unique_id
except ValueError: # wrong number of arguments
raise ValueError("Invalid configuration data %s" % repr(unique_id))
server_addr = params[constants.GLUSTER_HOST]
port = params[constants.GLUSTER_PORT]
volume = params[constants.GLUSTER_VOLUME]
self.volume = GlusterVolume(server_addr, port, volume)
self.path = path
self.driver = driver
self.full_path = io.PathJoin(self.volume.mount_point, self.path)
self.file = None
super(GlusterStorage, self).__init__(unique_id, children, size, params,
dyn_params, *args)
self.Attach()
def CreateFile(cls, path, size, create_folders=False,
_file_path_acceptance_fn=None):
"""Create a new file and its file device helper.
@param size: the size in MiBs the file should be truncated to.
@param create_folders: create the directories for the path if necessary
(using L{ganeti.utils.io.Makedirs})
@rtype: FileDeviceHelper
@return: The FileDeviceHelper object representing the object.
@raise errors.FileStoragePathError: if the file path is disallowed by policy
"""
if not _file_path_acceptance_fn:
_file_path_acceptance_fn = CheckFileStoragePathAcceptance
_file_path_acceptance_fn(path)
if create_folders:
folder = os.path.dirname(path)
io.Makedirs(folder)
try:
fd = os.open(path, os.O_RDWR | os.O_CREAT | os.O_EXCL)
f = os.fdopen(fd, "w")
f.truncate(size * 1024 * 1024)
f.close()
except EnvironmentError as err:
base.ThrowError("%s: can't create: %s", path, str(err))
return FileDeviceHelper(path,
_file_path_acceptance_fn=_file_path_acceptance_fn)
def Create(cls, unique_id, children, size, spindles, params, excl_stor,
dyn_params, **kwargs):
"""Create a new rbd device.
Provision a new rbd volume inside a RADOS pool.
"""
if not isinstance(unique_id, (tuple, list)) or len(unique_id) != 2:
raise errors.ProgrammerError("Invalid configuration data %s" %
str(unique_id))
if excl_stor:
raise errors.ProgrammerError("RBD device requested with"
" exclusive_storage")
rbd_pool = params[constants.LDP_POOL]
rbd_name = unique_id[1]
# Provision a new rbd volume (Image) inside the RADOS cluster.
cmd = cls.MakeRbdCmd(params, ["create", "-p", rbd_pool, rbd_name,
"--size", str(size)])
result = utils.RunCmd(cmd)
if result.failed:
base.ThrowError("rbd creation failed (%s): %s",
result.fail_reason, result.output)
return RADOSBlockDevice(unique_id, children, size, params, dyn_params,
**kwargs)
def Grow(self, amount, dryrun, backingstore, excl_stor):
"""Grow the Volume.
@type amount: integer
@param amount: the amount (in mebibytes) to grow with
@type dryrun: boolean
@param dryrun: whether to execute the operation in simulation mode
only, without actually increasing the size
"""
if not backingstore:
return
if not self.Attach():
base.ThrowError("Can't attach to extstorage device during Grow()")
if dryrun:
# we do not support dry runs of resize operations for now.
return
new_size = self.size + amount
# Call the External Storage's grow script,
# to grow an existing Volume inside the External Storage
_ExtStorageAction(constants.ES_ACTION_GROW,
self.unique_id,
self.ext_params,
size=self.size,
grow=new_size,
name=self.name,
uuid=self.uuid)
def _CheckExtStorageFile(base_dir, filename, required):
"""Check prereqs for an ExtStorage file.
Check if file exists, if it is a regular file and in case it is
one of extstorage scripts if it is executable.
@type base_dir: string
@param base_dir: Base directory containing ExtStorage installations.
@type filename: string
@param filename: The basename of the ExtStorage file.
@type required: bool
@param required: Whether the file is required or not.
@rtype: String
@return: The file path if the file is found and is valid,
None if the file is not found and not required.
@raises BlockDeviceError: In case prereqs are not met
(found and not valid/executable, not found and required)
"""
file_path = utils.PathJoin(base_dir, filename)
try:
st = os.stat(file_path)
except EnvironmentError, err:
if not required:
logging.info("Optional file '%s' under path '%s' is missing",
filename, base_dir)
return None
base.ThrowError("File '%s' under path '%s' is missing (%s)" %
(filename, base_dir, utils.ErrnoOrStr(err)))
def _VolumeToBlockdev(cls, pool, volume_name):
"""Do the 'volume name'-to-'rbd block device' resolving.
@type pool: string
@param pool: RADOS pool to use
@type volume_name: string
@param volume_name: the name of the volume whose device we search for
@rtype: string or None
@return: block device path if the volume is mapped, else None
"""
try:
# Newer versions of the rbd tool support json output formatting. Use it
# if available.
showmap_cmd = cls.MakeRbdCmd({}, ["showmapped", "--format", "json"])
result = utils.RunCmd(showmap_cmd)
if result.failed:
logging.error("rbd JSON output formatting returned error (%s): %s,"
"falling back to plain output parsing",
result.fail_reason, result.output)
raise RbdShowmappedJsonError
return cls._ParseRbdShowmappedJson(result.output, pool, volume_name)
except RbdShowmappedJsonError:
# For older versions of rbd, we have to parse the plain / text output
# manually.
showmap_cmd = cls.MakeRbdCmd({}, ["showmapped", "-p", pool])
result = utils.RunCmd(showmap_cmd)
if result.failed:
base.ThrowError("rbd showmapped failed (%s): %s",
result.fail_reason, result.output)
return cls._ParseRbdShowmappedPlain(result.output, volume_name)
def GetDevInfo(cls, show_data):
"""Parse details about a given DRBD minor.
This returns, if available, the local backing device (as a path)
and the local and remote (ip, port) information from a string
containing the output of the `drbdsetup show` command as returned
by DRBD8Dev._GetShowData.
This will return a dict with keys:
- local_dev
- meta_dev
- meta_index
- local_addr
- remote_addr
"""
if not show_data:
return {}
try:
# run pyparse
results = (cls._GetShowParser()).parseString(show_data)
except pyp.ParseException as err:
base.ThrowError("Can't parse drbdsetup show output: %s", str(err))
return cls._TransformParseResult(results)
def Import(self):
"""Builds the shell command for importing data to device.
@see: L{BlockDev.Import} for details
"""
base.ThrowError("Importing data is not supported for the"
" PersistentBlockDevice template")
def _CheckResult(result):
"""Throws an error if the given result is a failed one.
@param result: result from RunCmd
"""
if result.failed:
base.ThrowError("Command: %s error: %s - %s",
result.cmd, result.fail_reason, result.output)
def _ParseLvInfoLine(cls, line, sep):
"""Parse one line of the lvs output used in L{_GetLvInfo}.
"""
elems = line.strip().rstrip(sep).split(sep)
if len(elems) != 6:
base.ThrowError("Can't parse LVS output, len(%s) != 6", str(elems))
(status, major, minor, pe_size, stripes, pvs) = elems
if len(status) < 6:
base.ThrowError("lvs lv_attr is not at least 6 characters (%s)",
status)
try:
major = int(major)
minor = int(minor)
except (TypeError, ValueError), err:
base.ThrowError("lvs major/minor cannot be parsed: %s", str(err))
def GetUsermodeHelper(filename=_USERMODE_HELPER_FILE):
"""Returns DRBD usermode_helper currently set.
@type filename: string
@param filename: the filename to read the usermode helper from
@rtype: string
@return: the currently configured DRBD usermode helper
"""
try:
helper = utils.ReadFile(filename).splitlines()[0]
except EnvironmentError, err:
if err.errno == errno.ENOENT:
base.ThrowError("The file %s cannot be opened, check if the module"
" is loaded (%s)", filename, str(err))
else:
base.ThrowError("Can't read DRBD helper file %s: %s",
filename, str(err))