pvc/daemon-common/vm.py

#!/usr/bin/env python3

# vm.py - PVC client function library, VM fuctions
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2022 Joshua M. Boniface <joshua@boniface.me>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################

import time
import re
import lxml.objectify
import lxml.etree

from distutils.util import strtobool
from uuid import UUID
from concurrent.futures import ThreadPoolExecutor

import daemon_lib.common as common

import daemon_lib.ceph as ceph
from daemon_lib.network import set_sriov_vf_vm, unset_sriov_vf_vm


#
# Cluster search functions
#
def getClusterDomainList(zkhandler):
    # Get a list of UUIDs by listing the children of /domains
    uuid_list = zkhandler.children("base.domain")
    name_list = []
    # For each UUID, get the corresponding name from the data
    for uuid in uuid_list:
        name_list.append(zkhandler.read(("domain", uuid)))
    return uuid_list, name_list


def searchClusterByUUID(zkhandler, uuid):
    try:
        # Get the lists
        uuid_list, name_list = getClusterDomainList(zkhandler)
        # We're looking for UUID, so find that element ID
        index = uuid_list.index(uuid)
        # Get the name_list element at that index
        name = name_list[index]
    except ValueError:
        # We didn't find anything
        return None

    return name


def searchClusterByName(zkhandler, name):
    try:
        # Get the lists
        uuid_list, name_list = getClusterDomainList(zkhandler)
        # We're looking for name, so find that element ID
        index = name_list.index(name)
        # Get the uuid_list element at that index
        uuid = uuid_list[index]
    except ValueError:
        # We didn't find anything
        return None

    return uuid


def getDomainUUID(zkhandler, domain):
    # Validate that VM exists in cluster
    if common.validateUUID(domain):
        dom_name = searchClusterByUUID(zkhandler, domain)
        dom_uuid = searchClusterByName(zkhandler, dom_name)
    else:
        dom_uuid = searchClusterByName(zkhandler, domain)
        dom_name = searchClusterByUUID(zkhandler, dom_uuid)

    return dom_uuid


def getDomainName(zkhandler, domain):
    # Validate that VM exists in cluster
    if common.validateUUID(domain):
        dom_name = searchClusterByUUID(zkhandler, domain)
        dom_uuid = searchClusterByName(zkhandler, dom_name)
    else:
        dom_uuid = searchClusterByName(zkhandler, domain)
        dom_name = searchClusterByUUID(zkhandler, dom_uuid)

    return dom_name


#
# Helper functions
#
def change_state(zkhandler, dom_uuid, new_state):
    lock = zkhandler.exclusivelock(("domain.state", dom_uuid))
    with lock:
        zkhandler.write([(("domain.state", dom_uuid), new_state)])

        # Wait for 1/2 second to allow state to flow to all nodes
        time.sleep(0.5)


#
# Direct functions
#
def is_migrated(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    last_node = zkhandler.read(("domain.last_node", dom_uuid))
    if last_node:
        return True
    else:
        return False


def flush_locks(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Verify that the VM is in a stopped state; freeing locks is not safe otherwise
    state = zkhandler.read(("domain.state", dom_uuid))
    if state != "stop":
        return (
            False,
            'ERROR: VM "{}" is not in stopped state; flushing RBD locks on a running VM is dangerous.'.format(
                domain
            ),
        )

    # Tell the cluster to create a new OSD for the host
    flush_locks_string = "flush_locks {}".format(dom_uuid)
    zkhandler.write([("base.cmd.domain", flush_locks_string)])
    # Wait 1/2 second for the cluster to get the message and start working
    time.sleep(0.5)
    # Acquire a read lock, so we get the return exclusively
    lock = zkhandler.readlock("base.cmd.domain")
    with lock:
        try:
            result = zkhandler.read("base.cmd.domain").split()[0]
            if result == "success-flush_locks":
                message = 'Flushed locks on VM "{}"'.format(domain)
                success = True
            else:
                message = 'ERROR: Failed to flush locks on VM "{}"; check node logs for details.'.format(
                    domain
                )
                success = False
        except Exception:
            message = "ERROR: Command ignored by node."
            success = False

    # Acquire a write lock to ensure things go smoothly
    lock = zkhandler.writelock("base.cmd.domain")
    with lock:
        time.sleep(0.5)
        zkhandler.write([("base.cmd.domain", "")])

    return success, message


def define_vm(
    zkhandler,
    config_data,
    target_node,
    node_limit,
    node_selector,
    node_autostart,
    migration_method=None,
    profile=None,
    tags=[],
    initial_state="stop",
):
    # Parse the XML data
    try:
        parsed_xml = lxml.objectify.fromstring(config_data)
    except Exception:
        return False, "ERROR: Failed to parse XML data."
    dom_uuid = parsed_xml.uuid.text
    dom_name = parsed_xml.name.text

    # Ensure that the UUID and name are unique
    if searchClusterByUUID(zkhandler, dom_uuid) or searchClusterByName(
        zkhandler, dom_name
    ):
        return (
            False,
            'ERROR: Specified VM "{}" or UUID "{}" matches an existing VM on the cluster'.format(
                dom_name, dom_uuid
            ),
        )

    if not target_node:
        target_node = common.findTargetNode(zkhandler, dom_uuid)
    else:
        # Verify node is valid
        valid_node = common.verifyNode(zkhandler, target_node)
        if not valid_node:
            return False, 'ERROR: Specified node "{}" is invalid.'.format(target_node)

    # Validate the new RAM against the current active node
    node_total_memory = int(zkhandler.read(("node.memory.total", target_node)))
    if int(parsed_xml.memory.text) >= node_total_memory:
        return (
            False,
            'ERROR: VM configuration specifies more memory ({} MiB) than node "{}" has available ({} MiB).'.format(
                parsed_xml.memory.text, target_node, node_total_memory
            ),
        )

    # Validate the number of vCPUs against the current active node
    node_total_cpus = int(zkhandler.read(("node.data.static", target_node)).split()[0])
    if (node_total_cpus - 2) <= int(parsed_xml.vcpu.text):
        return (
            False,
            'ERROR: VM configuration specifies more vCPUs ({}) than node "{}" has available ({} minus 2).'.format(
                parsed_xml.vcpu.text, target_node, node_total_cpus
            ),
        )

    # If a SR-IOV network device is being added, set its used state
    dnetworks = common.getDomainNetworks(parsed_xml, {})
    for network in dnetworks:
        if network["type"] in ["direct", "hostdev"]:
            dom_node = zkhandler.read(("domain.node", dom_uuid))

            # Check if the network is already in use
            is_used = zkhandler.read(
                ("node.sriov.vf", dom_node, "sriov_vf.used", network["source"])
            )
            if is_used == "True":
                used_by_name = searchClusterByUUID(
                    zkhandler,
                    zkhandler.read(
                        (
                            "node.sriov.vf",
                            dom_node,
                            "sriov_vf.used_by",
                            network["source"],
                        )
                    ),
                )
                return (
                    False,
                    'ERROR: Attempted to use SR-IOV network "{}" which is already used by VM "{}" on node "{}".'.format(
                        network["source"], used_by_name, dom_node
                    ),
                )

            # We must update the "used" section
            set_sriov_vf_vm(
                zkhandler,
                dom_uuid,
                dom_node,
                network["source"],
                network["mac"],
                network["type"],
            )

    # Obtain the RBD disk list using the common functions
    ddisks = common.getDomainDisks(parsed_xml, {})
    rbd_list = []
    for disk in ddisks:
        if disk["type"] == "rbd":
            rbd_list.append(disk["name"])

    # Join the limit
    if isinstance(node_limit, list) and node_limit:
        formatted_node_limit = ",".join(node_limit)
    else:
        formatted_node_limit = ""

    # Join the RBD list
    if isinstance(rbd_list, list) and rbd_list:
        formatted_rbd_list = ",".join(rbd_list)
    else:
        formatted_rbd_list = ""

    # Add the new domain to Zookeeper
    zkhandler.write(
        [
            (("domain", dom_uuid), dom_name),
            (("domain.xml", dom_uuid), config_data),
            (("domain.state", dom_uuid), initial_state),
            (("domain.profile", dom_uuid), profile),
            (("domain.stats", dom_uuid), ""),
            (("domain.node", dom_uuid), target_node),
            (("domain.last_node", dom_uuid), ""),
            (("domain.failed_reason", dom_uuid), ""),
            (("domain.storage.volumes", dom_uuid), formatted_rbd_list),
            (("domain.console.log", dom_uuid), ""),
            (("domain.console.vnc", dom_uuid), ""),
            (("domain.meta.autostart", dom_uuid), node_autostart),
            (("domain.meta.migrate_method", dom_uuid), str(migration_method).lower()),
            (("domain.meta.node_limit", dom_uuid), formatted_node_limit),
            (("domain.meta.node_selector", dom_uuid), str(node_selector).lower()),
            (("domain.meta.tags", dom_uuid), ""),
            (("domain.migrate.sync_lock", dom_uuid), ""),
        ]
    )

    for tag in tags:
        tag_name = tag["name"]
        zkhandler.write(
            [
                (("domain.meta.tags", dom_uuid, "tag.name", tag_name), tag["name"]),
                (("domain.meta.tags", dom_uuid, "tag.type", tag_name), tag["type"]),
                (
                    ("domain.meta.tags", dom_uuid, "tag.protected", tag_name),
                    tag["protected"],
                ),
            ]
        )

    return True, 'Added new VM with Name "{}" and UUID "{}" to database.'.format(
        dom_name, dom_uuid
    )


def attach_vm_device(zkhandler, domain, device_spec_xml):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Verify that the VM is in a stopped state; freeing locks is not safe otherwise
    state = zkhandler.read(("domain.state", dom_uuid))
    if state != "start":
        return (
            False,
            'ERROR: VM "{}" is not in started state; live-add unneccessary.'.format(
                domain
            ),
        )

    # Tell the cluster to attach the device
    attach_device_string = "attach_device {} {}".format(dom_uuid, device_spec_xml)
    zkhandler.write([("base.cmd.domain", attach_device_string)])
    # Wait 1/2 second for the cluster to get the message and start working
    time.sleep(0.5)
    # Acquire a read lock, so we get the return exclusively
    lock = zkhandler.readlock("base.cmd.domain")
    with lock:
        try:
            result = zkhandler.read("base.cmd.domain").split()[0]
            if result == "success-attach_device":
                message = 'Attached device on VM "{}"'.format(domain)
                success = True
            else:
                message = 'ERROR: Failed to attach device on VM "{}"; check node logs for details.'.format(
                    domain
                )
                success = False
        except Exception:
            message = "ERROR: Command ignored by node."
            success = False

    # Acquire a write lock to ensure things go smoothly
    lock = zkhandler.writelock("base.cmd.domain")
    with lock:
        time.sleep(0.5)
        zkhandler.write([("base.cmd.domain", "")])

    return success, message


def detach_vm_device(zkhandler, domain, device_spec_xml):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Verify that the VM is in a stopped state; freeing locks is not safe otherwise
    state = zkhandler.read(("domain.state", dom_uuid))
    if state != "start":
        return (
            False,
            'ERROR: VM "{}" is not in started state; live-add unneccessary.'.format(
                domain
            ),
        )

    # Tell the cluster to detach the device
    detach_device_string = "detach_device {} {}".format(dom_uuid, device_spec_xml)
    zkhandler.write([("base.cmd.domain", detach_device_string)])
    # Wait 1/2 second for the cluster to get the message and start working
    time.sleep(0.5)
    # Acquire a read lock, so we get the return exclusively
    lock = zkhandler.readlock("base.cmd.domain")
    with lock:
        try:
            result = zkhandler.read("base.cmd.domain").split()[0]
            if result == "success-detach_device":
                message = 'Attached device on VM "{}"'.format(domain)
                success = True
            else:
                message = 'ERROR: Failed to detach device on VM "{}"; check node logs for details.'.format(
                    domain
                )
                success = False
        except Exception:
            message = "ERROR: Command ignored by node."
            success = False

    # Acquire a write lock to ensure things go smoothly
    lock = zkhandler.writelock("base.cmd.domain")
    with lock:
        time.sleep(0.5)
        zkhandler.write([("base.cmd.domain", "")])

    return success, message


def modify_vm_metadata(
    zkhandler,
    domain,
    node_limit,
    node_selector,
    node_autostart,
    provisioner_profile,
    migration_method,
):
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    update_list = list()

    if node_limit is not None:
        update_list.append((("domain.meta.node_limit", dom_uuid), node_limit))

    if node_selector is not None:
        update_list.append(
            (("domain.meta.node_selector", dom_uuid), str(node_selector).lower())
        )

    if node_autostart is not None:
        update_list.append((("domain.meta.autostart", dom_uuid), node_autostart))

    if provisioner_profile is not None:
        update_list.append((("domain.profile", dom_uuid), provisioner_profile))

    if migration_method is not None:
        update_list.append(
            (("domain.meta.migrate_method", dom_uuid), str(migration_method).lower())
        )

    if len(update_list) < 1:
        return False, "ERROR: No updates to apply."

    zkhandler.write(update_list)

    return True, 'Successfully modified PVC metadata of VM "{}".'.format(domain)


def modify_vm_tag(zkhandler, domain, action, tag, protected=False):
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    if action == "add":
        zkhandler.write(
            [
                (("domain.meta.tags", dom_uuid, "tag.name", tag), tag),
                (("domain.meta.tags", dom_uuid, "tag.type", tag), "user"),
                (("domain.meta.tags", dom_uuid, "tag.protected", tag), protected),
            ]
        )

        return True, 'Successfully added tag "{}" to VM "{}".'.format(tag, domain)
    elif action == "remove":
        if not zkhandler.exists(("domain.meta.tags", dom_uuid, "tag", tag)):
            return False, 'The tag "{}" does not exist.'.format(tag)

        if zkhandler.read(("domain.meta.tags", dom_uuid, "tag.type", tag)) != "user":
            return (
                False,
                'The tag "{}" is not a user tag and cannot be removed.'.format(tag),
            )

        if bool(
            strtobool(
                zkhandler.read(("domain.meta.tags", dom_uuid, "tag.protected", tag))
            )
        ):
            return False, 'The tag "{}" is protected and cannot be removed.'.format(tag)

        zkhandler.delete([(("domain.meta.tags", dom_uuid, "tag", tag))])

        return True, 'Successfully removed tag "{}" from VM "{}".'.format(tag, domain)
    else:
        return False, "Specified tag action is not available."


def modify_vm(zkhandler, domain, restart, new_vm_config):
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)
    dom_name = getDomainName(zkhandler, domain)

    # Parse and valiate the XML
    try:
        parsed_xml = lxml.objectify.fromstring(new_vm_config)
    except Exception:
        return False, "ERROR: Failed to parse new XML data."

    # Get our old network list for comparison purposes
    old_vm_config = zkhandler.read(("domain.xml", dom_uuid))
    old_parsed_xml = lxml.objectify.fromstring(old_vm_config)
    old_dnetworks = common.getDomainNetworks(old_parsed_xml, {})

    # Validate the new RAM against the current active node
    node_name = zkhandler.read(("domain.node", dom_uuid))
    node_total_memory = int(zkhandler.read(("node.memory.total", node_name)))
    if int(parsed_xml.memory.text) >= node_total_memory:
        return (
            False,
            'ERROR: Updated VM configuration specifies more memory ({} MiB) than node "{}" has available ({} MiB).'.format(
                parsed_xml.memory.text, node_name, node_total_memory
            ),
        )

    # Validate the number of vCPUs against the current active node
    node_total_cpus = int(zkhandler.read(("node.data.static", node_name)).split()[0])
    if (node_total_cpus - 2) <= int(parsed_xml.vcpu.text):
        return (
            False,
            'ERROR: Updated VM configuration specifies more vCPUs ({}) than node "{}" has available ({} minus 2).'.format(
                parsed_xml.vcpu.text, node_name, node_total_cpus
            ),
        )

    # If a SR-IOV network device is being added, set its used state
    dnetworks = common.getDomainNetworks(parsed_xml, {})
    for network in dnetworks:
        # Ignore networks that are already there
        if network["source"] in [net["source"] for net in old_dnetworks]:
            continue

        if network["type"] in ["direct", "hostdev"]:
            dom_node = zkhandler.read(("domain.node", dom_uuid))

            # Check if the network is already in use
            is_used = zkhandler.read(
                ("node.sriov.vf", dom_node, "sriov_vf.used", network["source"])
            )
            if is_used == "True":
                used_by_name = searchClusterByUUID(
                    zkhandler,
                    zkhandler.read(
                        (
                            "node.sriov.vf",
                            dom_node,
                            "sriov_vf.used_by",
                            network["source"],
                        )
                    ),
                )
                return (
                    False,
                    'ERROR: Attempted to use SR-IOV network "{}" which is already used by VM "{}" on node "{}".'.format(
                        network["source"], used_by_name, dom_node
                    ),
                )

            # We must update the "used" section
            set_sriov_vf_vm(
                zkhandler,
                dom_uuid,
                dom_node,
                network["source"],
                network["mac"],
                network["type"],
            )

    # If a SR-IOV network device is being removed, unset its used state
    for network in old_dnetworks:
        if network["type"] in ["direct", "hostdev"]:
            if network["mac"] not in [n["mac"] for n in dnetworks]:
                dom_node = zkhandler.read(("domain.node", dom_uuid))
                # We must update the "used" section
                unset_sriov_vf_vm(zkhandler, dom_node, network["source"])

    # Obtain the RBD disk list using the common functions
    ddisks = common.getDomainDisks(parsed_xml, {})
    rbd_list = []
    for disk in ddisks:
        if disk["type"] == "rbd":
            rbd_list.append(disk["name"])

    # Join the RBD list
    if isinstance(rbd_list, list) and rbd_list:
        formatted_rbd_list = ",".join(rbd_list)
    else:
        formatted_rbd_list = ""

    # Add the modified config to Zookeeper
    zkhandler.write(
        [
            (("domain", dom_uuid), dom_name),
            (("domain.storage.volumes", dom_uuid), formatted_rbd_list),
            (("domain.xml", dom_uuid), new_vm_config),
        ]
    )

    if restart:
        change_state(zkhandler, dom_uuid, "restart")

    return True, 'Successfully modified configuration of VM "{}".'.format(domain)


def dump_vm(zkhandler, domain):
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Gram the domain XML and dump it to stdout
    vm_xml = zkhandler.read(("domain.xml", dom_uuid))

    return True, vm_xml


def rename_vm(zkhandler, domain, new_domain):
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Verify that the VM is in a stopped state; renaming is not supported otherwise
    state = zkhandler.read(("domain.state", dom_uuid))
    if state != "stop":
        return (
            False,
            'ERROR: VM "{}" is not in stopped state; VMs cannot be renamed while running.'.format(
                domain
            ),
        )

    # Parse and valiate the XML
    vm_config = common.getDomainXML(zkhandler, dom_uuid)

    # Obtain the RBD disk list using the common functions
    ddisks = common.getDomainDisks(vm_config, {})
    pool_list = []
    rbd_list = []
    for disk in ddisks:
        if disk["type"] == "rbd":
            pool_list.append(disk["name"].split("/")[0])
            rbd_list.append(disk["name"].split("/")[1])

    # Rename each volume in turn
    for idx, rbd in enumerate(rbd_list):
        rbd_new = re.sub(r"{}".format(domain), new_domain, rbd)
        # Skip renaming if nothing changed
        if rbd_new == rbd:
            continue
        ceph.rename_volume(zkhandler, pool_list[idx], rbd, rbd_new)

    # Replace the name in the config
    vm_config_new = (
        lxml.etree.tostring(vm_config, encoding="ascii", method="xml")
        .decode()
        .replace(domain, new_domain)
    )

    # Get VM information
    _b, dom_info = get_info(zkhandler, dom_uuid)

    # Undefine the old VM
    undefine_vm(zkhandler, dom_uuid)

    # Define the new VM
    define_vm(
        zkhandler,
        vm_config_new,
        dom_info["node"],
        dom_info["node_limit"],
        dom_info["node_selector"],
        dom_info["node_autostart"],
        migration_method=dom_info["migration_method"],
        profile=dom_info["profile"],
        tags=dom_info["tags"],
        initial_state="stop",
    )

    # If the VM is migrated, store that
    if dom_info["migrated"] != "no":
        zkhandler.write([(("domain.last_node", dom_uuid), dom_info["last_node"])])

    return True, 'Successfully renamed VM "{}" to "{}".'.format(domain, new_domain)


def undefine_vm(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Shut down the VM
    current_vm_state = zkhandler.read(("domain.state", dom_uuid))
    if current_vm_state != "stop":
        change_state(zkhandler, dom_uuid, "stop")

    # Gracefully terminate the class instances
    change_state(zkhandler, dom_uuid, "delete")

    # Delete the configurations
    zkhandler.delete([("domain", dom_uuid)])

    return True, 'Undefined VM "{}" from the cluster.'.format(domain)


def remove_vm(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    disk_list = common.getDomainDiskList(zkhandler, dom_uuid)

    # Shut down the VM
    current_vm_state = zkhandler.read(("domain.state", dom_uuid))
    if current_vm_state != "stop":
        change_state(zkhandler, dom_uuid, "stop")

    # Wait for 1 second to allow state to flow to all nodes
    time.sleep(1)

    # Remove disks
    for disk in disk_list:
        # vmpool/vmname_volume
        try:
            disk_pool, disk_name = disk.split("/")
        except ValueError:
            continue

        retcode, message = ceph.remove_volume(zkhandler, disk_pool, disk_name)
        if not retcode:
            if re.match("^ERROR: No volume with name", message):
                continue
            else:
                return False, message

    # Gracefully terminate the class instances
    change_state(zkhandler, dom_uuid, "delete")

    # Wait for 1/2 second to allow state to flow to all nodes
    time.sleep(0.5)

    # Delete the VM configuration from Zookeeper
    zkhandler.delete([("domain", dom_uuid)])

    return True, 'Removed VM "{}" and its disks from the cluster.'.format(domain)


def start_vm(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Set the VM to start
    change_state(zkhandler, dom_uuid, "start")

    return True, 'Starting VM "{}".'.format(domain)


def restart_vm(zkhandler, domain, wait=False):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and verify we're OK to proceed
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state != "start":
        return False, 'ERROR: VM "{}" is not in "start" state!'.format(domain)

    retmsg = 'Restarting VM "{}".'.format(domain)

    # Set the VM to restart
    change_state(zkhandler, dom_uuid, "restart")

    if wait:
        while zkhandler.read(("domain.state", dom_uuid)) == "restart":
            time.sleep(0.5)
        retmsg = 'Restarted VM "{}"'.format(domain)

    return True, retmsg


def shutdown_vm(zkhandler, domain, wait=False):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and verify we're OK to proceed
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state != "start":
        return False, 'ERROR: VM "{}" is not in "start" state!'.format(domain)

    retmsg = 'Shutting down VM "{}"'.format(domain)

    # Set the VM to shutdown
    change_state(zkhandler, dom_uuid, "shutdown")

    if wait:
        while zkhandler.read(("domain.state", dom_uuid)) == "shutdown":
            time.sleep(0.5)
        retmsg = 'Shut down VM "{}"'.format(domain)

    return True, retmsg


def stop_vm(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Set the VM to stop
    change_state(zkhandler, dom_uuid, "stop")

    return True, 'Forcibly stopping VM "{}".'.format(domain)


def disable_vm(zkhandler, domain, force=False):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and perform a shutdown/stop if VM is online
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state in ["start"]:
        if force:
            change_state(zkhandler, dom_uuid, "stop")
            # Wait for the command to be registered by the node
            time.sleep(0.5)
        else:
            change_state(zkhandler, dom_uuid, "shutdown")
            # Wait for the shutdown to complete
            while zkhandler.read(("domain.state", dom_uuid)) != "stop":
                time.sleep(0.5)

    # Set the VM to disable
    change_state(zkhandler, dom_uuid, "disable")

    return True, 'Disabled VM "{}".'.format(domain)


def update_vm_sriov_nics(zkhandler, dom_uuid, source_node, target_node):
    # Update all the SR-IOV device states on both nodes, used during migrations but called by the node-side
    vm_config = zkhandler.read(("domain.xml", dom_uuid))
    parsed_xml = lxml.objectify.fromstring(vm_config)
    dnetworks = common.getDomainNetworks(parsed_xml, {})
    retcode = True
    retmsg = ""
    for network in dnetworks:
        if network["type"] in ["direct", "hostdev"]:
            # Check if the network is already in use
            is_used = zkhandler.read(
                ("node.sriov.vf", target_node, "sriov_vf.used", network["source"])
            )
            if is_used == "True":
                used_by_name = searchClusterByUUID(
                    zkhandler,
                    zkhandler.read(
                        (
                            "node.sriov.vf",
                            target_node,
                            "sriov_vf.used_by",
                            network["source"],
                        )
                    ),
                )
                if retcode:
                    retcode_this = False
                    retmsg = 'Attempting to use SR-IOV network "{}" which is already used by VM "{}"'.format(
                        network["source"], used_by_name
                    )
            else:
                retcode_this = True

            # We must update the "used" section
            if retcode_this:
                # This conditional ensure that if we failed the is_used check, we don't try to overwrite the information of a VF that belongs to another VM
                set_sriov_vf_vm(
                    zkhandler,
                    dom_uuid,
                    target_node,
                    network["source"],
                    network["mac"],
                    network["type"],
                )
            # ... but we still want to free the old node in an case
            unset_sriov_vf_vm(zkhandler, source_node, network["source"])

            if not retcode_this:
                retcode = retcode_this

    return retcode, retmsg


def move_vm(zkhandler, domain, target_node, wait=False, force_live=False):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and verify we're OK to proceed
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state != "start":
        # If the current state isn't start, preserve it; we're not doing live migration
        target_state = current_state
    else:
        if force_live:
            target_state = "migrate-live"
        else:
            target_state = "migrate"

    current_node = zkhandler.read(("domain.node", dom_uuid))

    if not target_node:
        target_node = common.findTargetNode(zkhandler, dom_uuid)
    else:
        # Verify node is valid
        valid_node = common.verifyNode(zkhandler, target_node)
        if not valid_node:
            return False, 'ERROR: Specified node "{}" is invalid.'.format(target_node)

        # Check if node is within the limit
        node_limit = zkhandler.read(("domain.meta.node_limit", dom_uuid))
        if node_limit and target_node not in node_limit.split(","):
            return (
                False,
                'ERROR: Specified node "{}" is not in the allowed list of nodes for VM "{}".'.format(
                    target_node, domain
                ),
            )

        # Verify if node is current node
        if target_node == current_node:
            last_node = zkhandler.read(("domain.last_node", dom_uuid))
            if last_node:
                zkhandler.write([(("domain.last_node", dom_uuid), "")])
                return True, 'Making temporary migration permanent for VM "{}".'.format(
                    domain
                )

            return False, 'ERROR: VM "{}" is already running on node "{}".'.format(
                domain, current_node
            )

    if not target_node:
        return (
            False,
            'ERROR: Could not find a valid migration target for VM "{}".'.format(
                domain
            ),
        )

    retmsg = 'Permanently migrating VM "{}" to node "{}".'.format(domain, target_node)

    lock = zkhandler.exclusivelock(("domain.state", dom_uuid))
    with lock:
        zkhandler.write(
            [
                (("domain.state", dom_uuid), target_state),
                (("domain.node", dom_uuid), target_node),
                (("domain.last_node", dom_uuid), ""),
            ]
        )

        # Wait for 1/2 second for migration to start
        time.sleep(0.5)

    # Update any SR-IOV NICs
    update_vm_sriov_nics(zkhandler, dom_uuid, current_node, target_node)

    if wait:
        while zkhandler.read(("domain.state", dom_uuid)) == target_state:
            time.sleep(0.5)
        retmsg = 'Permanently migrated VM "{}" to node "{}"'.format(domain, target_node)

    return True, retmsg


def migrate_vm(
    zkhandler, domain, target_node, force_migrate, wait=False, force_live=False
):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and verify we're OK to proceed
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state != "start":
        # If the current state isn't start, preserve it; we're not doing live migration
        target_state = current_state
    else:
        if force_live:
            target_state = "migrate-live"
        else:
            target_state = "migrate"

    current_node = zkhandler.read(("domain.node", dom_uuid))
    last_node = zkhandler.read(("domain.last_node", dom_uuid))

    if last_node and not force_migrate:
        return False, 'ERROR: VM "{}" has been previously migrated.'.format(domain)

    if not target_node:
        target_node = common.findTargetNode(zkhandler, dom_uuid)
    else:
        # Verify node is valid
        valid_node = common.verifyNode(zkhandler, target_node)
        if not valid_node:
            return False, 'ERROR: Specified node "{}" is invalid.'.format(target_node)

        # Check if node is within the limit
        node_limit = zkhandler.read(("domain.meta.node_limit", dom_uuid))
        if node_limit and target_node not in node_limit.split(","):
            return (
                False,
                'ERROR: Specified node "{}" is not in the allowed list of nodes for VM "{}".'.format(
                    target_node, domain
                ),
            )

        # Verify if node is current node
        if target_node == current_node:
            return False, 'ERROR: VM "{}" is already running on node "{}".'.format(
                domain, current_node
            )

    if not target_node:
        return (
            False,
            'ERROR: Could not find a valid migration target for VM "{}".'.format(
                domain
            ),
        )

    # Don't overwrite an existing last_node when using force_migrate
    real_current_node = current_node  # Used for the SR-IOV update
    if last_node and force_migrate:
        current_node = last_node

    retmsg = 'Migrating VM "{}" to node "{}".'.format(domain, target_node)

    lock = zkhandler.exclusivelock(("domain.state", dom_uuid))
    with lock:
        zkhandler.write(
            [
                (("domain.state", dom_uuid), target_state),
                (("domain.node", dom_uuid), target_node),
                (("domain.last_node", dom_uuid), current_node),
            ]
        )

        # Wait for 1/2 second for migration to start
        time.sleep(0.5)

    # Update any SR-IOV NICs
    update_vm_sriov_nics(zkhandler, dom_uuid, real_current_node, target_node)

    if wait:
        while zkhandler.read(("domain.state", dom_uuid)) == target_state:
            time.sleep(0.5)
        retmsg = 'Migrated VM "{}" to node "{}"'.format(domain, target_node)

    return True, retmsg


def unmigrate_vm(zkhandler, domain, wait=False, force_live=False):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get state and verify we're OK to proceed
    current_state = zkhandler.read(("domain.state", dom_uuid))
    if current_state != "start":
        # If the current state isn't start, preserve it; we're not doing live migration
        target_state = current_state
    else:
        if force_live:
            target_state = "migrate-live"
        else:
            target_state = "migrate"

    current_node = zkhandler.read(("domain.node", dom_uuid))
    target_node = zkhandler.read(("domain.last_node", dom_uuid))

    if target_node == "":
        return False, 'ERROR: VM "{}" has not been previously migrated.'.format(domain)

    retmsg = 'Unmigrating VM "{}" back to node "{}".'.format(domain, target_node)

    lock = zkhandler.exclusivelock(("domain.state", dom_uuid))
    with lock:
        zkhandler.write(
            [
                (("domain.state", dom_uuid), target_state),
                (("domain.node", dom_uuid), target_node),
                (("domain.last_node", dom_uuid), ""),
            ]
        )

        # Wait for 1/2 second for migration to start
        time.sleep(0.5)

    # Update any SR-IOV NICs
    update_vm_sriov_nics(zkhandler, dom_uuid, current_node, target_node)

    if wait:
        while zkhandler.read(("domain.state", dom_uuid)) == target_state:
            time.sleep(0.5)
        retmsg = 'Unmigrated VM "{}" back to node "{}"'.format(domain, target_node)

    return True, retmsg


def get_console_log(zkhandler, domain, lines=1000):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: Could not find VM "{}" in the cluster!'.format(domain)

    # Get the data from ZK
    console_log = zkhandler.read(("domain.console.log", dom_uuid))

    if console_log is None:
        return True, ""

    # Shrink the log buffer to length lines
    shrunk_log = console_log.split("\n")[-lines:]
    loglines = "\n".join(shrunk_log)

    return True, loglines


def get_info(zkhandler, domain):
    # Validate that VM exists in cluster
    dom_uuid = getDomainUUID(zkhandler, domain)
    if not dom_uuid:
        return False, 'ERROR: No VM named "{}" is present in the cluster.'.format(
            domain
        )

    # Gather information from XML config and print it
    domain_information = common.getInformationFromXML(zkhandler, dom_uuid)
    if not domain_information:
        return False, 'ERROR: Could not get information about VM "{}".'.format(domain)

    return True, domain_information


def get_list(zkhandler, node, state, tag, limit, is_fuzzy=True, negate=False):
    if node:
        # Verify node is valid
        if not common.verifyNode(zkhandler, node):
            return False, 'Specified node "{}" is invalid.'.format(node)

    if state:
        valid_states = [
            "start",
            "restart",
            "shutdown",
            "stop",
            "disable",
            "fail",
            "migrate",
            "unmigrate",
            "provision",
        ]
        if state not in valid_states:
            return False, 'VM state "{}" is not valid.'.format(state)

    full_vm_list = zkhandler.children("base.domain")
    full_vm_list.sort()

    # Set our limit to a sensible regex
    if limit:
        # Check if the limit is a UUID
        is_limit_uuid = False
        try:
            uuid_obj = UUID(limit, version=4)
            limit = str(uuid_obj)
            is_limit_uuid = True
        except ValueError:
            pass

        if is_fuzzy and not is_limit_uuid:
            try:
                # Implcitly assume fuzzy limits
                if not re.match(r"\^.*", limit):
                    limit = ".*" + limit
                if not re.match(r".*\$", limit):
                    limit = limit + ".*"
            except Exception as e:
                return False, "Regex Error: {}".format(e)

    get_vm_info = dict()
    for vm in full_vm_list:
        name = zkhandler.read(("domain", vm))
        is_limit_match = False
        is_tag_match = False
        is_node_match = False
        is_state_match = False

        # Check on limit
        if limit:
            # Try to match the limit against the UUID (if applicable) and name
            try:
                if is_limit_uuid and re.fullmatch(limit, vm):
                    is_limit_match = True
                if re.fullmatch(limit, name):
                    is_limit_match = True
            except Exception as e:
                return False, "Regex Error: {}".format(e)
        else:
            is_limit_match = True

        if tag:
            vm_tags = zkhandler.children(("domain.meta.tags", vm))
            if negate and tag not in vm_tags:
                is_tag_match = True
            if not negate and tag in vm_tags:
                is_tag_match = True
        else:
            is_tag_match = True

        # Check on node
        if node:
            vm_node = zkhandler.read(("domain.node", vm))
            if negate and vm_node != node:
                is_node_match = True
            if not negate and vm_node == node:
                is_node_match = True
        else:
            is_node_match = True

        # Check on state
        if state:
            vm_state = zkhandler.read(("domain.state", vm))
            if negate and vm_state != state:
                is_state_match = True
            if not negate and vm_state == state:
                is_state_match = True
        else:
            is_state_match = True

        get_vm_info[vm] = (
            True
            if is_limit_match and is_tag_match and is_node_match and is_state_match
            else False
        )

    # Obtain our VM data in a thread pool
    # This helps parallelize the numerous Zookeeper calls a bit, within the bounds of the GIL, and
    # should help prevent this task from becoming absurdly slow with very large numbers of VMs.
    # The max_workers is capped at 32 to avoid creating an absurd number of threads especially if
    # the list gets called multiple times simultaneously by the API, but still provides a noticeable
    # speedup.
    vm_execute_list = [vm for vm in full_vm_list if get_vm_info[vm]]
    vm_data_list = list()
    with ThreadPoolExecutor(max_workers=32, thread_name_prefix="vm_list") as executor:
        futures = []
        for vm_uuid in vm_execute_list:
            futures.append(
                executor.submit(common.getInformationFromXML, zkhandler, vm_uuid)
            )
        for future in futures:
            try:
                vm_data_list.append(future.result())
            except Exception:
                pass

    return True, sorted(vm_data_list, key=lambda d: d["name"])