Joshua Boniface
31f252ad9b
Implements the ability for a client to watch almost-live domain
console logs from the hypervisors. It does this using a deque-based
"tail -f" mechanism (with a configurable buffer per-VM) that watches
the domain console logfile in the (configurable) directory every
half-second. It then stores the current buffer in Zookeeper when
changed, where a client can then request it, either as a static piece
of text in the `less` pager, or via a similar "tail -f" functionality
implemented using fixed line splitting and comparison to provide a
generally-seamless output.
Enabling this feature requires each guest VM to implement a Libvirt
serial log and write its (text) console to it, for example using the
default logging directory:
```
<serial type='pty'>
<log file='/var/log/libvirt/vmname.log' append='off'/>
<serial>
```
The append mode can be either on or off; on grows files unbounded,
off causes the log (and hence the PVC log data) to be truncated on
initial VM startup from offline. The administrator must choose how
they best want to handle this until Libvirt implements their own
clog-type logging format.
478 lines
18 KiB
Python
478 lines
18 KiB
Python
#!/usr/bin/env python3
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# DomainInstance.py - Class implementing a PVC virtual machine in pvcd
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# Part of the Parallel Virtual Cluster (PVC) system
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#
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# Copyright (C) 2018 Joshua M. Boniface <joshua@boniface.me>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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###############################################################################
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import os
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import sys
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import uuid
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import socket
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import time
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import threading
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import libvirt
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import kazoo.client
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import pvcd.log as log
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import pvcd.zkhandler as zkhandler
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import pvcd.DomainConsoleWatcherInstance as DomainConsoleWatcherInstance
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class DomainInstance(object):
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# Initialization function
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def __init__(self, domuuid, zk_conn, config, logger, this_node):
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# Passed-in variables on creation
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self.domuuid = domuuid
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self.domname = zkhandler.readdata(zk_conn, '/domains/{}'.format(domuuid))
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self.zk_conn = zk_conn
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self.config = config
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self.logger = logger
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self.this_node = this_node
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# These will all be set later
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self.node = None
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self.state = None
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self.instart = False
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self.inrestart = False
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self.inmigrate = False
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self.inreceive = False
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self.inshutdown = False
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self.instop = False
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# Libvirt domuuid
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self.dom = self.lookupByUUID(self.domuuid)
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# Log watcher instance
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self.console_log_instance = DomainConsoleWatcherInstance.DomainConsoleWatcherInstance(self.domuuid, self.domname, self.zk_conn, self.config, self.logger, self.this_node)
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# Watch for changes to the state field in Zookeeper
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@self.zk_conn.DataWatch('/domains/{}/state'.format(self.domuuid))
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def watch_state(data, stat, event=""):
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if event and event.type == 'DELETED':
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# The key has been deleted after existing before; terminate this watcher
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# because this class instance is about to be reaped in Daemon.py
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return False
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# If we get a delete state, just terminate outselves
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if data == None:
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return
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# Otherwise perform a management command
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else:
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self.manage_vm_state()
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# Get data functions
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def getstate(self):
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return self.state
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def getnode(self):
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return self.node
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def getdom(self):
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return self.dom
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def getmemory(self):
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try:
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memory = int(self.dom.info()[2] / 1024)
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except:
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memory = 0
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return memory
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def getvcpus(self):
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try:
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vcpus = int(self.dom.info()[3])
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except:
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vcpus = 0
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return vcpus
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# Manage local node domain_list
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def addDomainToList(self):
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if not self.domuuid in self.this_node.domain_list:
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try:
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# Add the domain to the domain_list array
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self.this_node.domain_list.append(self.domuuid)
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# Push the change up to Zookeeper
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zkhandler.writedata(self.zk_conn, { '/nodes/{}/runningdomains'.format(self.this_node.name): ' '.join(self.this_node.domain_list) })
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except Exception as e:
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self.logger.out('Error adding domain to list: {}'.format(e), state='c')
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def removeDomainFromList(self):
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if self.domuuid in self.this_node.domain_list:
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try:
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# Remove the domain from the domain_list array
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self.this_node.domain_list.remove(self.domuuid)
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# Push the change up to Zookeeper
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zkhandler.writedata(self.zk_conn, { '/nodes/{}/runningdomains'.format(self.this_node.name): ' '.join(self.this_node.domain_list) })
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except Exception as e:
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self.logger.out('Error removing domain from list: {}'.format(e), state='c')
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# Start up the VM
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def start_vm(self):
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# Start the log watcher
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self.console_log_instance.start()
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self.logger.out('Starting VM', state='i', prefix='Domain {}:'.format(self.domuuid))
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self.instart = True
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# Start up a new Libvirt connection
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libvirt_name = "qemu:///system"
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lv_conn = libvirt.open(libvirt_name)
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if lv_conn == None:
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self.logger.out('Failed to open local libvirt connection', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.instart = False
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return
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# Try to get the current state in case it's already running
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try:
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self.dom = self.lookupByUUID(self.domuuid)
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curstate = self.dom.state()[0]
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except:
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curstate = 'notstart'
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if curstate == libvirt.VIR_DOMAIN_RUNNING:
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# If it is running just update the model
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self.addDomainToList()
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zkhandler.writedata(self.zk_conn, { '/domains/{}/failedreason'.format(self.domuuid): '' })
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else:
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# Or try to create it
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try:
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# Grab the domain information from Zookeeper
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xmlconfig = zkhandler.readdata(self.zk_conn, '/domains/{}/xml'.format(self.domuuid))
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dom = lv_conn.createXML(xmlconfig, 0)
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self.addDomainToList()
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self.logger.out('Successfully started VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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self.dom = dom
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zkhandler.writedata(self.zk_conn, { '/domains/{}/failedreason'.format(self.domuuid): '' })
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except libvirt.libvirtError as e:
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self.logger.out('Failed to create VM', state='e', prefix='Domain {}:'.format(self.domuuid))
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'failed' })
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zkhandler.writedata(self.zk_conn, { '/domains/{}/failedreason'.format(self.domuuid): str(e) })
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self.dom = None
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lv_conn.close()
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self.instart = False
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# Restart the VM
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def restart_vm(self):
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self.logger.out('Restarting VM', state='i', prefix='Domain {}:'.format(self.domuuid))
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self.inrestart = True
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# Start up a new Libvirt connection
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libvirt_name = "qemu:///system"
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lv_conn = libvirt.open(libvirt_name)
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if lv_conn == None:
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self.logger.out('Failed to open local libvirt connection', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.inrestart = False
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return
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self.shutdown_vm()
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self.start_vm()
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self.addDomainToList()
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'start' })
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lv_conn.close()
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self.inrestart = False
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# Stop the VM forcibly without updating state
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def terminate_vm(self):
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self.logger.out('Terminating VM', state='i', prefix='Domain {}:'.format(self.domuuid))
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self.instop = True
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try:
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self.dom.destroy()
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except AttributeError:
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self.logger.out('Failed to terminate VM', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.removeDomainFromList()
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self.logger.out('Successfully terminated VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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self.dom = None
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self.instop = False
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# Stop the log watcher
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self.console_log_instance.stop()
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# Stop the VM forcibly
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def stop_vm(self):
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self.logger.out('Forcibly stopping VM', state='i', prefix='Domain {}:'.format(self.domuuid))
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self.instop = True
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try:
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self.dom.destroy()
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except AttributeError:
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self.logger.out('Failed to stop VM', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.removeDomainFromList()
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if self.inrestart == False:
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'stop' })
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self.logger.out('Successfully stopped VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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self.dom = None
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self.instop = False
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# Stop the log watcher
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self.console_log_instance.stop()
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# Shutdown the VM gracefully
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def shutdown_vm(self):
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self.logger.out('Gracefully stopping VM', state='i', prefix='Domain {}:'.format(self.domuuid))
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self.inshutdown = True
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self.dom.shutdown()
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try:
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tick = 0
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while self.dom.state()[0] == libvirt.VIR_DOMAIN_RUNNING and tick < 60:
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tick += 1
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time.sleep(0.5)
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if tick >= 60:
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self.logger.out('Shutdown timeout expired', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.stop_vm()
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self.inshutdown = False
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return
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except:
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pass
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self.removeDomainFromList()
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if self.inrestart == False:
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'stop' })
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self.logger.out('Successfully shutdown VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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self.dom = None
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self.inshutdown = False
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# Stop the log watcher
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self.console_log_instance.stop()
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def live_migrate_vm(self, dest_node):
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try:
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dest_lv_conn = libvirt.open('qemu+tcp://{}/system'.format(self.node))
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if dest_lv_conn == None:
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raise
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except:
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self.logger.out('Failed to open connection to qemu+tcp://{}/system; aborting migration.'.format(self.node), state='e', prefix='Domain {}:'.format(self.domuuid))
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return False
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try:
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target_dom = self.dom.migrate(dest_lv_conn, libvirt.VIR_MIGRATE_LIVE, None, None, 0)
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if target_dom == None:
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raise
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self.logger.out('Successfully migrated VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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except:
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dest_lv_conn.close()
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return False
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dest_lv_conn.close()
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return True
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# Migrate the VM to a target host
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def migrate_vm(self):
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self.inmigrate = True
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self.logger.out('Migrating VM to node "{}"'.format(self.node), state='i', prefix='Domain {}:'.format(self.domuuid))
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try:
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migrate_ret = self.live_migrate_vm(self.node)
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except:
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migrate_ret = True
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if not migrate_ret:
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self.logger.out('Could not live migrate VM; shutting down to migrate instead', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.shutdown_vm()
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time.sleep(1)
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else:
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self.removeDomainFromList()
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time.sleep(1)
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'start' })
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self.inmigrate = False
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# Stop the log watcher
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self.console_log_instance.stop()
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# Receive the migration from another host (wait until VM is running)
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def receive_migrate(self):
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# Start the log watcher
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self.console_log_instance.start()
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self.inreceive = True
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self.logger.out('Receiving migration', state='i', prefix='Domain {}:'.format(self.domuuid))
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while True:
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time.sleep(0.5)
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self.state = zkhandler.readdata(self.zk_conn, '/domains/{}/state'.format(self.domuuid))
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self.dom = self.lookupByUUID(self.domuuid)
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if self.dom == None and self.state == 'migrate':
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continue
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if self.state != 'migrate':
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break
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try:
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if self.dom.state()[0] == libvirt.VIR_DOMAIN_RUNNING:
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break
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except:
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continue
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try:
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dom_state = self.dom.state()[0]
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except AttributeError:
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dom_state = None
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if dom_state == libvirt.VIR_DOMAIN_RUNNING:
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self.addDomainToList()
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self.logger.out('Successfully received migrated VM', state='o', prefix='Domain {}:'.format(self.domuuid))
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else:
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self.logger.out('Failed to receive migrated VM', state='e', prefix='Domain {}:'.format(self.domuuid))
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self.inreceive = False
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#
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# Main function to manage a VM (taking only self)
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#
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def manage_vm_state(self):
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# Give ourselves a bit of leeway time
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time.sleep(0.2)
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# Get the current values from zookeeper (don't rely on the watch)
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self.state = zkhandler.readdata(self.zk_conn, '/domains/{}/state'.format(self.domuuid))
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self.node = zkhandler.readdata(self.zk_conn, '/domains/{}/node'.format(self.domuuid))
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# Check the current state of the VM
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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:
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running = libvirt.VIR_DOMAIN_NOSTATE
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self.logger.out('VM state change for "{}": {} {}'.format(self.domuuid, self.state, self.node), state='i')
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#######################
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# Handle state changes
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#######################
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# Valid states are:
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# start
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# migrate
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# restart
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# shutdown
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# stop
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# Conditional pass one - Are we already performing an action
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if self.instart == False \
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and self.inrestart == False \
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and self.inmigrate == False \
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and self.inreceive == False \
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and self.inshutdown == False \
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and self.instop == False:
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# Conditional pass two - Is this VM configured to run on this node
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if self.node == self.this_node.name:
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# Conditional pass three - Is this VM currently running on this node
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if running == libvirt.VIR_DOMAIN_RUNNING:
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# VM is already running and should be
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if self.state == "start":
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# Start the log watcher
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self.console_log_instance.start()
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# Add domain to running list
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self.addDomainToList()
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# VM is already running and should be but stuck in migrate state
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elif self.state == "migrate":
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# Start the log watcher
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self.console_log_instance.start()
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'start' })
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# Add domain to running list
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self.addDomainToList()
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# VM should be restarted
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elif self.state == "restart":
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self.restart_vm()
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# VM should be shut down
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elif self.state == "shutdown":
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self.shutdown_vm()
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# VM should be stopped
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elif self.state == "stop":
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self.stop_vm()
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else:
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# VM should be started
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if self.state == "start":
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# Start the domain
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self.start_vm()
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# VM should be migrated to this node
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elif self.state == "migrate":
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# Receive the migration
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self.receive_migrate()
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# VM should be restarted (i.e. started since it isn't running)
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if self.state == "restart":
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zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'start' })
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# VM should be shut down; ensure it's gone from this node's domain_list
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elif self.state == "shutdown":
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self.removeDomainFromList()
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# Stop the log watcher
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self.console_log_instance.stop()
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# VM should be stoped; ensure it's gone from this node's domain_list
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elif self.state == "stop":
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self.removeDomainFromList()
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# Stop the log watcher
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self.console_log_instance.stop()
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else:
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# Conditional pass three - Is this VM currently running on this node
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if running == libvirt.VIR_DOMAIN_RUNNING:
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# VM should be migrated away from this node
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if self.state == "migrate":
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self.migrate_vm()
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# VM should be terminated
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else:
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self.terminate_vm()
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# This function is a wrapper for libvirt.lookupByUUID which fixes some problems
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# 1. Takes a text UUID and handles converting it to bytes
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# 2. Try's it and returns a sensible value if not
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def lookupByUUID(self, tuuid):
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lv_conn = None
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dom = None
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libvirt_name = "qemu:///system"
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# Convert the text UUID to bytes
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buuid = uuid.UUID(tuuid).bytes
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# Try
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try:
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# Open a libvirt connection
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lv_conn = libvirt.open(libvirt_name)
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if lv_conn == None:
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self.logger.out('Failed to open local libvirt connection', state='e', prefix='Domain {}:'.format(self.domuuid))
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return dom
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# Lookup the UUID
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dom = lv_conn.lookupByUUID(buuid)
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# Fail
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except:
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pass
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# After everything
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finally:
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# Close the libvirt connection
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if lv_conn != None:
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lv_conn.close()
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# Return the dom object (or None)
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return dom
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