gantt/nova/block_device.py
Vishvananda Ishaya b7426f2b51 Automatically convert device names
In the past, users have been able to specify xvda or xvdb and it
has worked. We are now validating device names against the expected
name from the backend, and this causes confusion, especially for lxc
which expecting device names to be /dev/a /dev/b /dev/c etc.

This patch addresses the issue by automatically converting between
different formats. The proper format for the backend will be returned
by the api. Includes tests to verify that the conversion works and
that the lxc values work as expected.

Fixes bug 1046020

Change-Id: Iffa552ba05f89f70b6fb93043edf8882c8412215
2012-09-04 17:30:26 -07:00

142 lines
4.1 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 Isaku Yamahata <yamahata@valinux co jp>
# All Rights Reserved.
#
# 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 re
DEFAULT_ROOT_DEV_NAME = '/dev/sda1'
_DEFAULT_MAPPINGS = {'ami': 'sda1',
'ephemeral0': 'sda2',
'root': DEFAULT_ROOT_DEV_NAME,
'swap': 'sda3'}
def properties_root_device_name(properties):
"""get root device name from image meta data.
If it isn't specified, return None.
"""
root_device_name = None
# NOTE(yamahata): see image_service.s3.s3create()
for bdm in properties.get('mappings', []):
if bdm['virtual'] == 'root':
root_device_name = bdm['device']
# NOTE(yamahata): register_image's command line can override
# <machine>.manifest.xml
if 'root_device_name' in properties:
root_device_name = properties['root_device_name']
return root_device_name
_ephemeral = re.compile('^ephemeral(\d|[1-9]\d+)$')
def is_ephemeral(device_name):
return _ephemeral.match(device_name)
def ephemeral_num(ephemeral_name):
assert is_ephemeral(ephemeral_name)
return int(_ephemeral.sub('\\1', ephemeral_name))
def is_swap_or_ephemeral(device_name):
return device_name == 'swap' or is_ephemeral(device_name)
def mappings_prepend_dev(mappings):
"""Prepend '/dev/' to 'device' entry of swap/ephemeral virtual type"""
for m in mappings:
virtual = m['virtual']
if (is_swap_or_ephemeral(virtual) and
(not m['device'].startswith('/'))):
m['device'] = '/dev/' + m['device']
return mappings
_dev = re.compile('^/dev/')
def strip_dev(device_name):
"""remove leading '/dev/'"""
return _dev.sub('', device_name) if device_name else device_name
_pref = re.compile('^((x?v|s)d)')
def strip_prefix(device_name):
""" remove both leading /dev/ and xvd or sd or vd """
device_name = strip_dev(device_name)
return _pref.sub('', device_name)
def instance_block_mapping(instance, bdms):
root_device_name = instance['root_device_name']
if root_device_name is None:
return _DEFAULT_MAPPINGS
mappings = {}
mappings['ami'] = strip_dev(root_device_name)
mappings['root'] = root_device_name
default_ephemeral_device = instance.get('default_ephemeral_device')
if default_ephemeral_device:
mappings['ephemeral0'] = default_ephemeral_device
default_swap_device = instance.get('default_swap_device')
if default_swap_device:
mappings['swap'] = default_swap_device
ebs_devices = []
# 'ephemeralN', 'swap' and ebs
for bdm in bdms:
if bdm['no_device']:
continue
# ebs volume case
if (bdm['volume_id'] or bdm['snapshot_id']):
ebs_devices.append(bdm['device_name'])
continue
virtual_name = bdm['virtual_name']
if not virtual_name:
continue
if is_swap_or_ephemeral(virtual_name):
mappings[virtual_name] = bdm['device_name']
# NOTE(yamahata): I'm not sure how ebs device should be numbered.
# Right now sort by device name for deterministic
# result.
if ebs_devices:
nebs = 0
ebs_devices.sort()
for ebs in ebs_devices:
mappings['ebs%d' % nebs] = ebs
nebs += 1
return mappings
def match_device(device):
"""Matches device name and returns prefix, suffix"""
match = re.match("(^/dev/x{0,1}[a-z]{0,1}d{0,1})([a-z]+)[0-9]*$", device)
if not match:
return None
return match.groups()