127 lines
4.0 KiB
Python
127 lines
4.0 KiB
Python
"""
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Copyright 2013 Rackspace, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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"""
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import abc
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import plumbum
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import stevedore
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import structlog
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_global_manager = None
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class HardwareSupport(object):
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"""These are just guidelines to suggest values that might be returned by
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calls to `evaluate_hardware_support`. No HardwareManager in mainline
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teeth-agent will ever offer a value greater than `MAINLINE`. Service
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Providers should feel free to return values greater than SERVICE_PROVIDER
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to distinguish between additional levels of support.
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"""
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NONE = 0
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GENERIC = 1
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MAINLINE = 2
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SERVICE_PROVIDER = 3
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class BlockDevice(object):
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def __init__(self, name, size, start_sector):
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self.name = name
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self.size = size
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self.start_sector = start_sector
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class HardwareManager(object):
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@abc.abstractmethod
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def evaluate_hardware_support(cls):
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pass
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@abc.abstractmethod
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def get_primary_mac_address(self):
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pass
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@abc.abstractmethod
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def get_os_install_device(self):
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pass
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class GenericHardwareManager(HardwareManager):
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def evaluate_hardware_support(cls):
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return HardwareSupport.GENERIC
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def get_primary_mac_address(self):
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return open('/sys/class/net/eth0/address', 'r').read().strip('\n')
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def _cmd(self, command_name):
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"""Mocking plumbum is frustratingly difficult. Instead, mock this."""
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return plumbum.local[command_name]
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def _list_block_devices(self):
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report = self._cmd('blockdev')('--report').strip()
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lines = report.split('\n')
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lines = [line.split() for line in lines]
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startsec_idx = lines[0].index('StartSec')
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device_idx = lines[0].index('Device')
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size_idx = lines[0].index('Size')
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return [BlockDevice(line[device_idx],
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int(line[size_idx]),
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int(line[startsec_idx]))
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for line
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in lines[1:]]
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def get_os_install_device(self):
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# Assume anything with a start sector other than 0, is a partition
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block_devices = [device for device in self._list_block_devices()
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if device.start_sector == 0]
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# Find the first device larger than 4GB, assume it is the OS disk
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# TODO(russellhaering): This isn't a valid assumption in all cases,
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# is there a more reasonable default behavior?
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block_devices.sort(key=lambda device: device.size)
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for device in block_devices:
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if device.size >= (4 * pow(1024, 3)):
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return device.name
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def _compare_extensions(ext1, ext2):
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mgr1 = ext1.obj
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mgr2 = ext2.obj
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return mgr1.evaluate_hardware_support() - mgr2.evaluate_hardware_support()
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def get_manager():
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global _global_manager
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if not _global_manager:
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log = structlog.get_logger()
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extension_manager = stevedore.ExtensionManager(
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namespace='teeth_agent.hardware_managers',
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invoke_on_load=True)
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# There will always be at least one extension available (the
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# GenericHardwareManager).
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preferred_extension = sorted(extension_manager, _compare_extensions)[0]
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preferred_manager = preferred_extension.obj
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if preferred_manager.evaluate_hardware_support() <= 0:
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raise RuntimeError('No suitable HardwareManager could be found')
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log.info('selected hardware manager',
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manager_name=preferred_extension.entry_point_target)
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_global_manager = preferred_manager
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return _global_manager
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