pvc/VMInstance.py

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#!/usr/bin/env python3
# VMInstance.py - Class implementing a PVC virtual machine and run by pvcd
# Part of the Parallel Virtual Cluster (PVC) system
#
# Copyright (C) 2018 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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/>.
#
###############################################################################
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import os, sys, uuid, socket, time, threading, libvirt, kazoo.client
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class VMInstance:
def __init__(self, domuuid, zk, thishypervisor):
# Passed-in variables on creation
self.domuuid = domuuid
self.zkey = '/domains/%s' % domuuid
self.zk = zk
self.thishypervisor = thishypervisor
# These will all be set later
self.hypervisor = None
self.state = None
self.instart = False
self.instop = False
self.inshutdown = False
self.inmigrate = False
self.inreceive = False
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self.dom = lookupByUUID(self.domuuid)
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# Watch for changes to the hypervisor field in Zookeeper
@zk.DataWatch(self.zkey + '/hypervisor')
def watch_hypervisor(data, stat, event=""):
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try:
self.hypervisor = data.decode('ascii')
except:
return
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self.manage_vm_state()
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# Watch for changes to the state field in Zookeeper
@zk.DataWatch(self.zkey + '/state')
def watch_state(data, stat, event=""):
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try:
self.state = data.decode('ascii')
except:
return
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self.manage_vm_state()
# Get data functions
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def getstate(self):
return self.state
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def gethypervisor(self):
return self.hypervisor
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# Start up the VM
def start_vm(self, xmlconfig):
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print(">>> %s - Starting VM" % self.domuuid)
self.instart = True
# Start up a new Libvirt connection
libvirt_name = "qemu:///system"
conn = libvirt.open(libvirt_name)
if conn == None:
print('>>> %s - Failed to open local libvirt connection.' % self.domuuid)
self.instart = False
return
try:
dom = conn.createXML(xmlconfig, 0)
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except libvirt.libvirtError as e:
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print('>>> %s - Failed to create VM' % self.domuuid)
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self.zk.set(self.zkey + '/state', 'stop'.encode('ascii'))
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if not self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.append(self.domuuid)
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conn.close()
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self.dom = dom
self.instart = False
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# Stop the VM forcibly
def stop_vm(self):
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print(">>> %s - Forcibly stopping VM" % self.domuuid)
self.instop = True
try:
self.dom.destroy()
except AttributeError:
pass
if self.domuuid in self.thishypervisor.domain_list:
try:
self.thishypervisor.domain_list.remove(self.domuuid)
except ValueError:
pass
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self.zk.set(self.zkey + '/state', 'stop'.encode('ascii'))
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self.dom = None
self.instop = False
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# Shutdown the VM gracefully
def shutdown_vm(self):
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print(">>> %s - Gracefully stopping VM" % self.domuuid)
self.inshutdown = True
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self.dom.shutdown()
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try:
tick = 0
while self.dom.state()[0] == libvirt.VIR_DOMAIN_RUNNING and tick < 60:
tick += 1
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time.sleep(0.5)
if tick >= 60:
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print(">>> %s - Shutdown timeout expired" % self.domuuid)
self.stop_vm()
self.inshutdown = False
return
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except:
pass
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if self.domuuid in self.thishypervisor.domain_list:
try:
self.thishypervisor.domain_list.remove(self.domuuid)
except ValueError:
pass
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self.zk.set(self.zkey + '/state', 'stop'.encode('ascii'))
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self.dom = None
self.inshutdown = False
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def live_migrate_vm(self, dest_hypervisor):
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try:
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dest_conn = libvirt.open('qemu+tcp://%s/system' % self.hypervisor)
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if dest_conn == None:
raise
except:
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print('>>> %s - Failed to open connection to qemu+tcp://%s/system; aborting migration' % self.hypervisor)
return 1
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try:
target_dom = self.dom.migrate(dest_conn, libvirt.VIR_MIGRATE_LIVE, None, None, 0)
if target_dom == None:
raise
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print('>>> %s - Migrated successfully' % self.domuuid)
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except:
dest_conn.close()
return 1
dest_conn.close()
return 0
# Migrate the VM to a target host
def migrate_vm(self):
self.inmigrate = True
print('>>> %s - Migrating VM to %s' % (self.domuuid, self.hypervisor))
migrate_ret = self.live_migrate_vm(self.hypervisor)
if migrate_ret != 0:
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print('>>> %s - Could not live migrate VM; shutting down instead' % self.domuuid)
self.shutdown_vm()
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time.sleep(0.5)
else:
try:
self.thishypervisor.domain_list.remove(self.domuuid)
except ValueError:
pass
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self.inmigrate = False
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# Receive the migration from another host (wait until VM is running)
def receive_migrate(self):
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print('>>> %s - Receiving migration' % self.domuuid)
self.inreceive = True
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while True:
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self.dom = lookupByUUID(self.domuuid)
if self.dom == None:
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time.sleep(0.2)
continue
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if self.dom.state()[0] == libvirt.VIR_DOMAIN_RUNNING:
break
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self.zk.set(self.zkey + '/state', 'start'.encode('ascii'))
if not self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.append(self.domuuid)
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print('>>> %s - Migrated successfully' % self.domuuid)
self.inreceive = False
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#
# Main function to manage a VM (taking only self)
#
def manage_vm_state(self):
# Check the current state of the VM
try:
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if self.dom != None:
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running, reason = self.dom.state()
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else:
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raise
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except:
running = libvirt.VIR_DOMAIN_NOSTATE
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# VM should be stopped
if running == libvirt.VIR_DOMAIN_RUNNING and self.state == "stop" and self.hypervisor == self.thishypervisor.name and self.instop == False:
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self.stop_vm()
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# VM should be shut down
elif running == libvirt.VIR_DOMAIN_RUNNING and self.state == "shutdown" and self.hypervisor == self.thishypervisor.name and self.inshutdown == False:
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self.shutdown_vm()
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# VM should be migrated to this hypervisor
elif running != libvirt.VIR_DOMAIN_RUNNING and self.state == "migrate" and self.hypervisor == self.thishypervisor.name and self.inreceive == False:
self.receive_migrate()
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# VM should be migrated away from this hypervisor
elif running == libvirt.VIR_DOMAIN_RUNNING and self.state == "migrate" and self.hypervisor != self.thishypervisor.name and self.inmigrate == False:
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self.migrate_vm()
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# VM is already running and should be
elif running == libvirt.VIR_DOMAIN_RUNNING and self.state == "start" and self.hypervisor == self.thishypervisor.name:
if not self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.append(self.domuuid)
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# VM should be started
elif running != libvirt.VIR_DOMAIN_RUNNING and self.state == "start" and self.hypervisor == self.thishypervisor.name and self.instart == False:
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# Grab the domain information from Zookeeper
domxml, domxmlstat = self.zk.get(self.zkey + '/xml')
domxml = str(domxml.decode('ascii'))
self.start_vm(domxml)
# This function is a wrapper for libvirt.lookupByUUID which fixes some problems
# 1. Takes a text UUID and handles converting it to bytes
# 2. Try's it and returns a sensible value if not
def lookupByUUID(tuuid):
conn = None
dom = None
libvirt_name = "qemu:///system"
# Convert the text UUID to bytes
buuid = uuid.UUID(tuuid).bytes
# Try
try:
# Open a libvirt connection
conn = libvirt.open(libvirt_name)
if conn == None:
print('>>> %s - Failed to open local libvirt connection.' % self.domuuid)
return dom
# Lookup the UUID
dom = conn.lookupByUUID(buuid)
# Fail
except:
pass
# After everything
finally:
# Close the libvirt connection
if conn != None:
conn.close()
# Return the dom object (or None)
return dom