ironic-python-agent/ironic_python_agent/hardware.py

# Copyright 2013 Rackspace, 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 abc
import functools
import os
import subprocess

import six
import stevedore

from ironic_python_agent import encoding
from ironic_python_agent.openstack.common import log
from ironic_python_agent import utils

_global_manager = None


class HardwareSupport(object):
    """These are just guidelines to suggest values that might be returned by
    calls to `evaluate_hardware_support`. No HardwareManager in mainline
    ironic-python-agent will ever offer a value greater than `MAINLINE`.
    Service Providers should feel free to return values greater than
    SERVICE_PROVIDER to distinguish between additional levels of support.
    """
    NONE = 0
    GENERIC = 1
    MAINLINE = 2
    SERVICE_PROVIDER = 3


class HardwareType(object):
    MAC_ADDRESS = 'mac_address'


class HardwareInfo(encoding.Serializable):
    def __init__(self, type, id):
        self.type = type
        self.id = id

    def serialize(self):
        return utils.get_ordereddict([
            ('type', self.type),
            ('id', self.id),
        ])


class BlockDevice(object):
    def __init__(self, name, size, start_sector):
        self.name = name
        self.size = size
        self.start_sector = start_sector


class NetworkInterface(object):
    def __init__(self, name, mac_addr):
        self.name = name
        self.mac_address = mac_addr
        # TODO(russellhaering): Pull these from LLDP
        self.switch_port_descr = None
        self.switch_chassis_descr = None


class HardwareManager(object):
    @abc.abstractmethod
    def evaluate_hardware_support(cls):
        pass

    @abc.abstractmethod
    def list_network_interfaces(self):
        pass

    @abc.abstractmethod
    def get_os_install_device(self):
        pass

    def list_hardware_info(self):
        hardware_info = []
        for interface in self.list_network_interfaces():
            hardware_info.append(HardwareInfo(HardwareType.MAC_ADDRESS,
                                              interface.mac_address))
        return hardware_info


class GenericHardwareManager(HardwareManager):
    def __init__(self):
        self.sys_path = '/sys'

        if os.path.isdir('/mnt/sys'):
            self.sys_path = '/mnt/sys'

    def evaluate_hardware_support(cls):
        return HardwareSupport.GENERIC

    def _get_interface_info(self, interface_name):
        addr_path = '{0}/class/net/{1}/address'.format(self.sys_path,
                                                     interface_name)
        addr_file = open(addr_path, 'r')
        mac_addr = addr_file.read().strip()
        return NetworkInterface(interface_name, mac_addr)

    def _is_device(self, interface_name):
        device_path = '{0}/class/net/{1}/device'.format(self.sys_path,
                                                      interface_name)
        return os.path.exists(device_path)

    def list_network_interfaces(self):
        iface_names = os.listdir('{0}/class/net'.format(self.sys_path))
        return [self._get_interface_info(name)
                for name in iface_names
                if self._is_device(name)]

    def _cmd(self, command):
        process = subprocess.Popen(command, stdout=subprocess.PIPE)
        return process.communicate()

    def _list_block_devices(self):
        report = self._cmd(['blockdev', '--report'])[0]
        lines = report.split('\n')
        lines = [line.split() for line in lines if line != '']
        startsec_idx = lines[0].index('StartSec')
        device_idx = lines[0].index('Device')
        size_idx = lines[0].index('Size')
        return [BlockDevice(line[device_idx],
                            int(line[size_idx]),
                            int(line[startsec_idx]))
                for line
                in lines[1:]]

    def get_os_install_device(self):
        # Assume anything with a start sector other than 0, is a partition
        block_devices = [device for device in self._list_block_devices()
                         if device.start_sector == 0]

        # Find the first device larger than 4GB, assume it is the OS disk
        # TODO(russellhaering): This isn't a valid assumption in all cases,
        #                       is there a more reasonable default behavior?
        block_devices.sort(key=lambda device: device.size)
        for device in block_devices:
            if device.size >= (4 * pow(1024, 3)):
                return device.name


def _compare_extensions(ext1, ext2):
    mgr1 = ext1.obj
    mgr2 = ext2.obj
    return mgr1.evaluate_hardware_support() - mgr2.evaluate_hardware_support()


def get_manager():
    global _global_manager

    if not _global_manager:
        LOG = log.getLogger()
        extension_manager = stevedore.ExtensionManager(
            namespace='ironic_python_agent.hardware_managers',
            invoke_on_load=True)

        # There will always be at least one extension available (the
        # GenericHardwareManager).
        if six.PY2:
            preferred_extension = sorted(
                    extension_manager,
                    _compare_extensions)[0]
        else:
            preferred_extension = sorted(
                    extension_manager,
                    key=functools.cmp_to_key(_compare_extensions))[0]

        preferred_manager = preferred_extension.obj

        if preferred_manager.evaluate_hardware_support() <= 0:
            raise RuntimeError('No suitable HardwareManager could be found')

        LOG.info('selected hardware manager {0}'.format(
                 preferred_extension.entry_point_target))

        _global_manager = preferred_manager

    return _global_manager