# Copyright 2013 Hewlett-Packard Development Company, L.P.
# 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.

"""
Ironic SSH power manager.

Provides basic power control of virtual machines via SSH.

For use in dev and test environments.

Currently supported environments are:
    Virtual Box (vbox)
    Virsh       (virsh)
    VMware      (vmware)
    Parallels   (parallels)
"""

import os

from oslo_concurrency import processutils
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import excutils
import retrying

from ironic.common import boot_devices
from ironic.common import exception
from ironic.common.i18n import _
from ironic.common.i18n import _LE
from ironic.common.i18n import _LW
from ironic.common import states
from ironic.common import utils
from ironic.conductor import task_manager
from ironic.drivers import base
from ironic.drivers import utils as driver_utils

libvirt_opts = [
    cfg.StrOpt('libvirt_uri',
               default='qemu:///system',
               help=_('libvirt URI.')),
    cfg.IntOpt('get_vm_name_attempts',
               default=3,
               help=_("Number of attempts to try to get VM name used by the "
                      "host that corresponds to a node's MAC address.")),
    cfg.IntOpt('get_vm_name_retry_interval',
               default=3,
               help=_("Number of seconds to wait between attempts to get "
                      "VM name used by the host that corresponds to a "
                      "node's MAC address.")),
]

CONF = cfg.CONF
CONF.register_opts(libvirt_opts, group='ssh')

LOG = logging.getLogger(__name__)

REQUIRED_PROPERTIES = {
    'ssh_address': _("IP address or hostname of the node to ssh into. "
                     "Required."),
    'ssh_username': _("username to authenticate as. Required."),
    'ssh_virt_type': _("virtualization software to use; one of vbox, virsh, "
                       "vmware, parallels. Required.")
}
OTHER_PROPERTIES = {
    'ssh_key_contents': _("private key(s). One of this, ssh_key_filename, "
                          "or ssh_password must be specified."),
    'ssh_key_filename': _("(list of) filename(s) of optional private key(s) "
                          "for authentication. One of this, ssh_key_contents, "
                          "or ssh_password must be specified."),
    'ssh_password': _("password to use for authentication or for unlocking a "
                      "private key. One of this, ssh_key_contents, or "
                      "ssh_key_filename must be specified."),
    'ssh_port': _("port on the node to connect to; default is 22. Optional.")
}
COMMON_PROPERTIES = REQUIRED_PROPERTIES.copy()
COMMON_PROPERTIES.update(OTHER_PROPERTIES)

# NOTE(dguerri) Generic boot device map. Virtualisation types that don't define
# a more specific one, will use this.
# This is left for compatibility with other modules and is still valid for
# virsh and vmware.
_BOOT_DEVICES_MAP = {
    boot_devices.DISK: 'hd',
    boot_devices.PXE: 'network',
    boot_devices.CDROM: 'cdrom',
}


def _get_boot_device_map(virt_type):
    if virt_type in ('virsh', 'vmware'):
        return _BOOT_DEVICES_MAP
    elif virt_type == 'vbox':
        return {
            boot_devices.DISK: 'disk',
            boot_devices.PXE: 'net',
            boot_devices.CDROM: 'dvd',
        }
    elif virt_type == 'parallels':
        return {
            boot_devices.DISK: 'hdd0',
            boot_devices.PXE: 'net0',
            boot_devices.CDROM: 'cdrom0',
        }
    else:
        raise exception.InvalidParameterValue(_(
            "SSHPowerDriver '%(virt_type)s' is not a valid virt_type.") %
            {'virt_type': virt_type})


def _get_command_sets(virt_type):
    """Retrieves the virt_type-specific commands to control power

    Required commands are as follows:

    base_cmd: Used by most sub-commands as the primary executable
    list_all: Lists all VMs (by virt_type identifier) that can be managed.
        One name per line, must not be quoted.
    list_running: Lists all running VMs (by virt_type identifier).
        One name per line, can be quoted.
    start_cmd / stop_cmd: Starts or stops the identified VM
    get_node_macs: Retrieves all MACs for an identified VM.
        One MAC per line, any standard format (see _normalize_mac)
    get_boot_device / set_boot_device: Gets or sets the primary boot device
    """
    if virt_type == 'vbox':
        return {
            'base_cmd': 'LC_ALL=C /usr/bin/VBoxManage',
            'start_cmd': 'startvm {_NodeName_}',
            'stop_cmd': 'controlvm {_NodeName_} poweroff',
            'reboot_cmd': 'controlvm {_NodeName_} reset',
            'list_all': "list vms|awk -F'\"' '{print $2}'",
            'list_running': 'list runningvms',
            'get_node_macs': (
                "showvminfo --machinereadable {_NodeName_} | "
                "awk -F '\"' '/macaddress/{print $2}'"),
            'set_boot_device': (
                '{_BaseCmd_} modifyvm {_NodeName_} '
                '--boot1 {_BootDevice_}'),
            'get_boot_device': (
                "{_BaseCmd_} showvminfo "
                "--machinereadable {_NodeName_} | "
                "awk -F '\"' '/boot1/{print $2}'"),
        }
    elif virt_type == 'vmware':
        return {
            'base_cmd': 'LC_ALL=C /bin/vim-cmd',
            'start_cmd': 'vmsvc/power.on {_NodeName_}',
            'stop_cmd': 'vmsvc/power.off {_NodeName_}',
            'reboot_cmd': 'vmsvc/power.reboot {_NodeName_}',
            'list_all': "vmsvc/getallvms | awk '$1 ~ /^[0-9]+$/ {print $1}'",
            # NOTE(arata): In spite of its name, list_running_cmd shows a
            #              single vmid, not a list. But it is OK.
            'list_running': (
                "vmsvc/power.getstate {_NodeName_} | "
                "grep 'Powered on' >/dev/null && "
                "echo '\"{_NodeName_}\"' || true"),
            # NOTE(arata): `true` is needed to handle a false vmid, which can
            #              be returned by list_cmd. In that case, get_node_macs
            #              returns an empty list rather than fails with
            #              non-zero status code.
            'get_node_macs': (
                "vmsvc/device.getdevices {_NodeName_} | "
                "grep macAddress | awk -F '\"' '{print $2}' || true"),
        }
    elif virt_type == "virsh":
        # NOTE(NobodyCam): changes to the virsh commands will impact CI
        #                  see https://review.openstack.org/83906
        #                  Change-Id: I160e4202952b7551b855dc7d91784d6a184cb0ed
        #                  for more detail.
        virsh_cmds = {
            'base_cmd': 'LC_ALL=C /usr/bin/virsh',
            'start_cmd': 'start {_NodeName_}',
            'stop_cmd': 'destroy {_NodeName_}',
            'reboot_cmd': 'reset {_NodeName_}',
            'list_all': "list --all | tail -n +2 | awk -F\" \" '{print $2}'",
            'list_running': (
                "list --all|grep running | "
                "awk -v qc='\"' -F\" \" '{print qc$2qc}'"),
            'get_node_macs': (
                "dumpxml {_NodeName_} | "
                "awk -F \"'\" '/mac address/{print $2}'| tr -d ':'"),
            'set_boot_device': (
                "EDITOR=\"sed -i '/<boot \(dev\|order\)=*\>/d;"
                "/<\/os>/i\<boot dev=\\\"{_BootDevice_}\\\"/>'\" "
                "{_BaseCmd_} edit {_NodeName_}"),
            'get_boot_device': (
                "{_BaseCmd_} dumpxml {_NodeName_} | "
                "awk '/boot dev=/ { gsub( \".*dev=\" Q, \"\" ); "
                "gsub( Q \".*\", \"\" ); print; }' "
                "Q=\"'\" RS=\"[<>]\" | "
                "head -1"),
        }

        if CONF.ssh.libvirt_uri:
            virsh_cmds['base_cmd'] += ' --connect %s' % CONF.ssh.libvirt_uri

        return virsh_cmds
    elif virt_type == 'parallels':
        return {
            'base_cmd': 'LC_ALL=C /usr/bin/prlctl',
            'start_cmd': 'start {_NodeName_}',
            'stop_cmd': 'stop {_NodeName_} --kill',
            'reboot_cmd': 'reset {_NodeName_}',
            'list_all': "list -a -o name |tail -n +2",
            'list_running': 'list -o name |tail -n +2',
            'get_node_macs': (
                "list -j -i \"{_NodeName_}\" | "
                "awk -F'\"' '/\"mac\":/ {print $4}' | "
                "sed 's/\\(..\\)\\(..\\)\\(..\\)\\(..\\)\\(..\\)\\(..\\)/"
                "\\1:\\2:\\3:\\4:\\5\\6/' | "
                "tr '[:upper:]' '[:lower:]'"),
            'set_boot_device': (
                "{_BaseCmd_} set {_NodeName_} "
                "--device-bootorder \"{_BootDevice_}\""),
            'get_boot_device': (
                "{_BaseCmd_} list -i {_NodeName_} | "
                "awk '/^Boot order:/ {print $3}'"),
        }
    else:
        raise exception.InvalidParameterValue(_(
            "SSHPowerDriver '%(virt_type)s' is not a valid virt_type, ") %
            {'virt_type': virt_type})


def _normalize_mac(mac):
    return mac.replace('-', '').replace(':', '').lower()


def _get_boot_device(ssh_obj, driver_info):
    """Get the current boot device.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :raises: SSHCommandFailed on an error from ssh.
    :raises: NotImplementedError if the virt_type does not support
        getting the boot device.
    :raises: NodeNotFound if could not find a VM corresponding to any
        of the provided MACs.

    """
    cmd_to_exec = driver_info['cmd_set'].get('get_boot_device')
    if cmd_to_exec:
        boot_device_map = _get_boot_device_map(driver_info['virt_type'])
        node_name = _get_hosts_name_for_node(ssh_obj, driver_info)
        base_cmd = driver_info['cmd_set']['base_cmd']
        cmd_to_exec = cmd_to_exec.replace('{_NodeName_}', node_name)
        cmd_to_exec = cmd_to_exec.replace('{_BaseCmd_}', base_cmd)
        stdout, stderr = _ssh_execute(ssh_obj, cmd_to_exec)
        return next((dev for dev, hdev in boot_device_map.items()
                     if hdev == stdout), None)
    else:
        raise NotImplementedError()


def _set_boot_device(ssh_obj, driver_info, device):
    """Set the boot device.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :param device: the boot device.
    :raises: SSHCommandFailed on an error from ssh.
    :raises: NotImplementedError if the virt_type does not support
        setting the boot device.
    :raises: NodeNotFound if could not find a VM corresponding to any
        of the provided MACs.

    """
    cmd_to_exec = driver_info['cmd_set'].get('set_boot_device')
    if cmd_to_exec:
        node_name = _get_hosts_name_for_node(ssh_obj, driver_info)
        base_cmd = driver_info['cmd_set']['base_cmd']
        cmd_to_exec = cmd_to_exec.replace('{_NodeName_}', node_name)
        cmd_to_exec = cmd_to_exec.replace('{_BootDevice_}', device)
        cmd_to_exec = cmd_to_exec.replace('{_BaseCmd_}', base_cmd)
        _ssh_execute(ssh_obj, cmd_to_exec)
    else:
        raise NotImplementedError()


def _ssh_execute(ssh_obj, cmd_to_exec):
    """Executes a command via ssh.

    Executes a command via ssh and returns a list of the lines of the
    output from the command.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param cmd_to_exec: command to execute.
    :returns: list of the lines of output from the command.
    :raises: SSHCommandFailed on an error from ssh.

    """
    try:
        output_list = processutils.ssh_execute(ssh_obj,
                                               cmd_to_exec)[0].split('\n')
    except Exception as e:
        LOG.error(_LE("Cannot execute SSH cmd %(cmd)s. Reason: %(err)s."),
                  {'cmd': cmd_to_exec, 'err': e})
        raise exception.SSHCommandFailed(cmd=cmd_to_exec)

    return output_list


def _parse_driver_info(node):
    """Gets the information needed for accessing the node.

    :param node: the Node of interest.
    :returns: dictionary of information.
    :raises: InvalidParameterValue if any required parameters are incorrect.
    :raises: MissingParameterValue if any required parameters are missing.

    """
    info = node.driver_info or {}
    missing_info = [key for key in REQUIRED_PROPERTIES if not info.get(key)]
    if missing_info:
        raise exception.MissingParameterValue(_(
            "SSHPowerDriver requires the following parameters to be set in "
            "node's driver_info: %s.") % missing_info)

    address = info.get('ssh_address')
    username = info.get('ssh_username')
    password = info.get('ssh_password')
    try:
        port = int(info.get('ssh_port', 22))
    except ValueError:
        raise exception.InvalidParameterValue(_(
            "SSHPowerDriver requires ssh_port to be integer value"))
    key_contents = info.get('ssh_key_contents')
    key_filename = info.get('ssh_key_filename')
    virt_type = info.get('ssh_virt_type')

    # NOTE(deva): we map 'address' from API to 'host' for common utils
    res = {
        'host': address,
        'username': username,
        'port': port,
        'virt_type': virt_type,
        'uuid': node.uuid
    }

    cmd_set = _get_command_sets(virt_type)
    res['cmd_set'] = cmd_set

    # Only one credential may be set (avoids complexity around having
    # precedence etc).
    if len([v for v in (password, key_filename, key_contents) if v]) != 1:
        raise exception.InvalidParameterValue(_(
            "SSHPowerDriver requires one and only one of password, "
            "key_contents and key_filename to be set."))
    if password:
        res['password'] = password
    elif key_contents:
        res['key_contents'] = key_contents
    else:
        if not os.path.isfile(key_filename):
            raise exception.InvalidParameterValue(_(
                "SSH key file %s not found.") % key_filename)
        res['key_filename'] = key_filename

    return res


def _get_power_status(ssh_obj, driver_info):
    """Returns a node's current power state.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :returns: one of ironic.common.states POWER_OFF, POWER_ON.
    :raises: NodeNotFound if could not find a VM corresponding to any
        of the provided MACs.

    """
    power_state = None
    node_name = _get_hosts_name_for_node(ssh_obj, driver_info)
    # Get a list of vms running on the host. If the command supports
    # it, explicitly specify the desired node."
    cmd_to_exec = "%s %s" % (driver_info['cmd_set']['base_cmd'],
                             driver_info['cmd_set']['list_running'])
    cmd_to_exec = cmd_to_exec.replace('{_NodeName_}', node_name)
    running_list = _ssh_execute(ssh_obj, cmd_to_exec)

    # Command should return a list of running vms. If the current node is
    # not listed then we can assume it is not powered on.
    quoted_node_name = '"%s"' % node_name
    for node in running_list:
        if not node:
            continue
        # 'node' here is a formatted output from the virt cli's. The
        # node name is either an exact match or quoted (optionally with
        # other information, e.g. vbox returns '"NodeName" {<uuid>}')
        if (quoted_node_name in node) or (node_name == node):
            power_state = states.POWER_ON
            break
    if not power_state:
        power_state = states.POWER_OFF

    return power_state


def _get_connection(node):
    """Returns an SSH client connected to a node.

    :param node: the Node.
    :returns: paramiko.SSHClient, an active ssh connection.

    """
    return utils.ssh_connect(_parse_driver_info(node))


def _get_hosts_name_for_node(ssh_obj, driver_info):
    """Get the name the host uses to reference the node.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :returns: the name of the node.
    :raises: NodeNotFound if could not find a VM corresponding to any of
        the provided MACs

    """

    @retrying.retry(
        retry_on_result=lambda v: v is None,
        retry_on_exception=lambda _: False,  # Do not retry on SSHCommandFailed
        stop_max_attempt_number=CONF.ssh.get_vm_name_attempts,
        wait_fixed=CONF.ssh.get_vm_name_retry_interval * 1000)
    def _with_retries():
        matched_name = None
        cmd_to_exec = "%s %s" % (driver_info['cmd_set']['base_cmd'],
                                 driver_info['cmd_set']['list_all'])
        full_node_list = _ssh_execute(ssh_obj, cmd_to_exec)
        LOG.debug("Retrieved Node List: %s" % repr(full_node_list))
        # for each node check Mac Addresses
        for node in full_node_list:
            if not node:
                continue
            LOG.debug("Checking Node: %s's Mac address." % node)
            cmd_to_exec = "%s %s" % (driver_info['cmd_set']['base_cmd'],
                                     driver_info['cmd_set']['get_node_macs'])
            cmd_to_exec = cmd_to_exec.replace('{_NodeName_}', node)
            hosts_node_mac_list = _ssh_execute(ssh_obj, cmd_to_exec)

            for host_mac in hosts_node_mac_list:
                if not host_mac:
                    continue
                for node_mac in driver_info['macs']:
                    if _normalize_mac(host_mac) in _normalize_mac(node_mac):
                        LOG.debug("Found Mac address: %s" % node_mac)
                        matched_name = node
                        break

                if matched_name:
                    break
            if matched_name:
                break

        return matched_name

    try:
        return _with_retries()
    except retrying.RetryError:
        raise exception.NodeNotFound(
            _("SSH driver was not able to find a VM with any of the "
              "specified MACs: %(macs)s for node %(node)s.") %
            {'macs': driver_info['macs'], 'node': driver_info['uuid']})


def _power_on(ssh_obj, driver_info):
    """Power ON this node.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :returns: one of ironic.common.states POWER_ON or ERROR.

    """
    current_pstate = _get_power_status(ssh_obj, driver_info)
    if current_pstate == states.POWER_ON:
        _power_off(ssh_obj, driver_info)

    node_name = _get_hosts_name_for_node(ssh_obj, driver_info)
    cmd_to_power_on = "%s %s" % (driver_info['cmd_set']['base_cmd'],
                                 driver_info['cmd_set']['start_cmd'])
    cmd_to_power_on = cmd_to_power_on.replace('{_NodeName_}', node_name)

    _ssh_execute(ssh_obj, cmd_to_power_on)

    current_pstate = _get_power_status(ssh_obj, driver_info)
    if current_pstate == states.POWER_ON:
        return current_pstate
    else:
        return states.ERROR


def _power_off(ssh_obj, driver_info):
    """Power OFF this node.

    :param ssh_obj: paramiko.SSHClient, an active ssh connection.
    :param driver_info: information for accessing the node.
    :returns: one of ironic.common.states POWER_OFF or ERROR.

    """
    current_pstate = _get_power_status(ssh_obj, driver_info)
    if current_pstate == states.POWER_OFF:
        return current_pstate

    node_name = _get_hosts_name_for_node(ssh_obj, driver_info)
    cmd_to_power_off = "%s %s" % (driver_info['cmd_set']['base_cmd'],
                                  driver_info['cmd_set']['stop_cmd'])
    cmd_to_power_off = cmd_to_power_off.replace('{_NodeName_}', node_name)

    _ssh_execute(ssh_obj, cmd_to_power_off)

    current_pstate = _get_power_status(ssh_obj, driver_info)
    if current_pstate == states.POWER_OFF:
        return current_pstate
    else:
        return states.ERROR


class SSHPower(base.PowerInterface):
    """SSH Power Interface.

    This PowerInterface class provides a mechanism for controlling the power
    state of virtual machines via SSH.

    NOTE: This driver supports VirtualBox and Virsh commands.
    NOTE: This driver does not currently support multi-node operations.
    """

    def get_properties(self):
        return COMMON_PROPERTIES

    def validate(self, task):
        """Check that the node's 'driver_info' is valid.

        Check that the node's 'driver_info' contains the requisite fields
        and that an SSH connection to the node can be established.

        :param task: a TaskManager instance containing the node to act on.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect or if ssh failed to connect to the node.
        :raises: MissingParameterValue if no ports are enrolled for the given
                 node.
        """
        if not driver_utils.get_node_mac_addresses(task):
            raise exception.MissingParameterValue(
                _("Node %s does not have any port associated with it."
                  ) % task.node.uuid)
        try:
            _get_connection(task.node)
        except exception.SSHConnectFailed as e:
            raise exception.InvalidParameterValue(_("SSH connection cannot"
                                                    " be established: %s") % e)

    def get_power_state(self, task):
        """Get the current power state of the task's node.

        Poll the host for the current power state of the task's node.

        :param task: a TaskManager instance containing the node to act on.
        :returns: power state. One of :class:`ironic.common.states`.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect.
        :raises: MissingParameterValue when a required parameter is missing
        :raises: NodeNotFound if could not find a VM corresponding to any
            of the provided MACs.
        :raises: SSHCommandFailed on an error from ssh.
        :raises: SSHConnectFailed if ssh failed to connect to the node.
        """
        driver_info = _parse_driver_info(task.node)
        driver_info['macs'] = driver_utils.get_node_mac_addresses(task)
        ssh_obj = _get_connection(task.node)
        return _get_power_status(ssh_obj, driver_info)

    @task_manager.require_exclusive_lock
    def set_power_state(self, task, pstate):
        """Turn the power on or off.

        Set the power state of the task's node.

        :param task: a TaskManager instance containing the node to act on.
        :param pstate: Either POWER_ON or POWER_OFF from :class:
            `ironic.common.states`.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect, or if the desired power state is invalid.
        :raises: MissingParameterValue when a required parameter is missing
        :raises: NodeNotFound if could not find a VM corresponding to any
            of the provided MACs.
        :raises: PowerStateFailure if it failed to set power state to pstate.
        :raises: SSHCommandFailed on an error from ssh.
        :raises: SSHConnectFailed if ssh failed to connect to the node.
        """
        driver_info = _parse_driver_info(task.node)
        driver_info['macs'] = driver_utils.get_node_mac_addresses(task)
        ssh_obj = _get_connection(task.node)

        if pstate == states.POWER_ON:
            state = _power_on(ssh_obj, driver_info)
        elif pstate == states.POWER_OFF:
            state = _power_off(ssh_obj, driver_info)
        else:
            raise exception.InvalidParameterValue(
                _("set_power_state called with invalid power state %s."
                  ) % pstate)

        if state != pstate:
            raise exception.PowerStateFailure(pstate=pstate)

    @task_manager.require_exclusive_lock
    def reboot(self, task):
        """Cycles the power to the task's node.

        Power cycles a node.

        :param task: a TaskManager instance containing the node to act on.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect.
        :raises: MissingParameterValue when a required parameter is missing
        :raises: NodeNotFound if could not find a VM corresponding to any
            of the provided MACs.
        :raises: PowerStateFailure if it failed to set power state to POWER_ON.
        :raises: SSHCommandFailed on an error from ssh.
        :raises: SSHConnectFailed if ssh failed to connect to the node.
        """
        driver_info = _parse_driver_info(task.node)
        driver_info['macs'] = driver_utils.get_node_mac_addresses(task)
        ssh_obj = _get_connection(task.node)

        # _power_on will turn the power off if it's already on.
        state = _power_on(ssh_obj, driver_info)

        if state != states.POWER_ON:
            raise exception.PowerStateFailure(pstate=states.POWER_ON)


class SSHManagement(base.ManagementInterface):

    def get_properties(self):
        return COMMON_PROPERTIES

    def validate(self, task):
        """Check that 'driver_info' contains SSH credentials.

        Validates whether the 'driver_info' property of the supplied
        task's node contains the required credentials information.

        :param task: a task from TaskManager.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect.
        :raises: MissingParameterValue if a required parameter is missing
        """
        _parse_driver_info(task.node)

    def get_supported_boot_devices(self, task):
        """Get a list of the supported boot devices.

        :param task: a task from TaskManager.
        :returns: A list with the supported boot devices defined
                  in :mod:`ironic.common.boot_devices`.

        """
        return list(_BOOT_DEVICES_MAP.keys())

    @task_manager.require_exclusive_lock
    def set_boot_device(self, task, device, persistent=False):
        """Set the boot device for the task's node.

        Set the boot device to use on next reboot of the node.

        :param task: a task from TaskManager.
        :param device: the boot device, one of
                       :mod:`ironic.common.boot_devices`.
        :param persistent: Boolean value. True if the boot device will
                           persist to all future boots, False if not.
                           Default: False. Ignored by this driver.
        :raises: InvalidParameterValue if an invalid boot device is
                 specified or if any connection parameters are incorrect.
        :raises: MissingParameterValue if a required parameter is missing
        :raises: SSHConnectFailed if ssh failed to connect to the node.
        :raises: SSHCommandFailed on an error from ssh.
        :raises: NotImplementedError if the virt_type does not support
            setting the boot device.
        :raises: NodeNotFound if could not find a VM corresponding to any
            of the provided MACs.

        """
        node = task.node
        driver_info = _parse_driver_info(node)
        if device not in self.get_supported_boot_devices(task):
            raise exception.InvalidParameterValue(_(
                "Invalid boot device %s specified.") % device)
        driver_info['macs'] = driver_utils.get_node_mac_addresses(task)
        ssh_obj = _get_connection(node)

        boot_device_map = _get_boot_device_map(driver_info['virt_type'])
        try:
            _set_boot_device(ssh_obj, driver_info, boot_device_map[device])
        except NotImplementedError:
            with excutils.save_and_reraise_exception():
                LOG.error(_LE("Failed to set boot device for node %(node)s, "
                              "virt_type %(vtype)s does not support this "
                              "operation"),
                          {'node': node.uuid,
                           'vtype': driver_info['virt_type']})

    def get_boot_device(self, task):
        """Get the current boot device for the task's node.

        Provides the current boot device of the node. Be aware that not
        all drivers support this.

        :param task: a task from TaskManager.
        :raises: InvalidParameterValue if any connection parameters are
            incorrect.
        :raises: MissingParameterValue if a required parameter is missing
        :raises: SSHConnectFailed if ssh failed to connect to the node.
        :raises: SSHCommandFailed on an error from ssh.
        :raises: NodeNotFound if could not find a VM corresponding to any
            of the provided MACs.
        :returns: a dictionary containing:

            :boot_device: the boot device, one of
                :mod:`ironic.common.boot_devices` or None if it is unknown.
            :persistent: Whether the boot device will persist to all
                future boots or not, None if it is unknown.

        """
        node = task.node
        driver_info = _parse_driver_info(node)
        driver_info['macs'] = driver_utils.get_node_mac_addresses(task)
        ssh_obj = _get_connection(node)
        response = {'boot_device': None, 'persistent': None}
        try:
            response['boot_device'] = _get_boot_device(ssh_obj, driver_info)
        except NotImplementedError:
            LOG.warning(_LW("Failed to get boot device for node %(node)s, "
                            "virt_type %(vtype)s does not support this "
                            "operation"),
                        {'node': node.uuid, 'vtype': driver_info['virt_type']})
        return response

    def get_sensors_data(self, task):
        """Get sensors data.

        Not implemented by this driver.

        :param task: a TaskManager instance.

        """
        raise NotImplementedError()