pvc/VMInstance.py

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#!/usr/bin/env python3
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import os, time, uuid, 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.dom = None
# Watch for changes to the hypervisor field in Zookeeper
@zk.DataWatch(self.zkey + '/hypervisor')
def watch_hypervisor(data, stat, event=""):
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if self.hypervisor != data.decode('ascii'):
self.hypervisor = data.decode('ascii')
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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if self.state != data.decode('ascii'):
self.state = data.decode('ascii')
self.manage_vm_state()
# Get data functions
def getdomuuid():
return self.domuuid
def getstate():
return self.state
def getdom():
return self.dom
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# Start up the VM
def start_vm(self, conn, xmlconfig):
print("Starting VM %s" % self.domuuid)
try:
dom = conn.createXML(xmlconfig, 0)
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except:
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print('Failed to create domain %s' % self.domuuid)
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self.zk.set(self.zkey + '/state', 'stop'.encode('ascii'))
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return None
if not self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.append(self.domuuid)
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return dom
# Stop the VM forcibly
def stop_vm(self):
print("Forcibly stopping VM %s" % self.domuuid)
self.dom.destroy()
if self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.remove(self.domuuid)
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# Shutdown the VM gracefully
def shutdown_vm(self):
print("Stopping VM %s" % self.domuuid)
self.dom.shutdown()
if self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.remove(self.domuuid)
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# Migrate the VM to a target host
def migrate_vm(self):
self.zk.set(self.zkey + '/status', b'migrate')
dest_conn = libvirt.open('qemu+ssh://%s/system' % target)
if dest_conn == None:
print('Failed to open connection to qemu+ssh://%s/system' % target)
exit(1)
target_dom = self.dom.migrate(dest_conn, libvirt.VIR_MIGRATE_LIVE, None, None, 0)
if target_dom == None:
print('Could not migrate to the new domain')
exit(1)
self.thishypervisor.domain_list.remove(self.domuuid)
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print('Migrated successfully')
dest_conn.close()
# Receive the migration from another host (wait until VM is running)
def receive_migrate(self):
while True:
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if self.dom == None or self.dom.state() != libvirt.VIR_DOMAIN_RUNNING:
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continue
else:
self.zk.set(self.zkey + '/status', b'start')
if not self.domuuid in self.thishypervisor.domain_list:
self.thishypervisor.domain_list.append(self.domuuid)
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break
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#
# Main function to manage a VM (taking only self)
#
def manage_vm_state(self):
# Start up a new Libvirt connection
libvirt_name = "qemu:///system"
conn = libvirt.open(libvirt_name)
if conn == None:
print('Failed to open local libvirt connection.')
exit(1)
# Check the current state of the VM
try:
self.dom = conn.lookupByUUID(uuid.UUID(self.domuuid).bytes)
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if self.dom != None:
running, reason = self.dom.state()
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else:
running = libvirt.VIR_DOMAIN_NOSTATE
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except:
running = libvirt.VIR_DOMAIN_NOSTATE
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if running == libvirt.VIR_DOMAIN_RUNNING and self.state == "stop" and self.hypervisor == self.thishypervisor.name:
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self.stop_vm()
if running == libvirt.VIR_DOMAIN_RUNNING and self.state == "shutdown" and self.hypervisor == self.thishypervisor.name:
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self.shutdown_vm()
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elif running != libvirt.VIR_DOMAIN_RUNNING and self.state == "migrate" and self.hypervisor == self.thishypervisor.name:
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self.receive_migrate()
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elif running == libvirt.VIR_DOMAIN_RUNNING and self.state == "migrate" and self.hypervisor != self.thishypervisor.name:
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self.migrate_vm()
elif running != libvirt.VIR_DOMAIN_RUNNING and self.state == "start" and self.hypervisor == self.thishypervisor.name:
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# Grab the domain information from Zookeeper
domxml, domxmlstat = self.zk.get(self.zkey + '/xml')
domxml = str(domxml.decode('ascii'))
self.dom = self.start_vm(conn, domxml)
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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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# The VM should now be running so return the domain and active connection
conn.close