本文首发于泊浮目的专栏： https://segmentfault.com/blog...
背景
在上篇文章中（ZStack源码剖析之二次开发——可扩展框架
），我们简单的了解了一下ZStack核心引擎的二次开发技巧。在这篇文章中，我们将一起来了解ZStack-Utility（即ZStack的Agent端）的二开姿势。
例子
我们以ZStack管理节点调用startVm这个api为例子，一起来看一下在agent上的执行逻辑。
def start(self):
http_server = kvmagent.get_http_server()
http_server.register_async_uri(self.KVM_START_VM_PATH, self.start_vm)首先，得注册一个http path用来接受reqeust。
@kvmagent.replyerror
def start_vm(self, req):
cmd = jsonobject.loads(req[http.REQUEST_BODY])
rsp = StartVmResponse()
try:
self._record_operation(cmd.vmInstanceUuid, self.VM_OP_START)
self._start_vm(cmd)
logger.debug('successfully started vm[uuid:%s, name:%s]' % (cmd.vmInstanceUuid, cmd.vmName))
except kvmagent.KvmError as e:
e_str = linux.get_exception_stacktrace()
logger.warn(e_str)
if "burst" in e_str and "Illegal" in e_str and "rate" in e_str:
rsp.error = "QoS exceed max limit, please check and reset it in zstack"
elif "cannot set up guest memory" in e_str:
logger.warn('unable to start vm[uuid:%s], %s' % (cmd.vmInstanceUuid, e_str))
rsp.error = "No enough physical memory for guest"
else:
rsp.error = e_str
err = self.handle_vfio_irq_conflict(cmd.vmInstanceUuid)
if err != "":
rsp.error = "%s, details: %s" % (err, rsp.error)
rsp.success = False
return jsonobject.dumps(rsp)直接进入主干逻辑，self._start_vm(cmd)。
@lock.lock('libvirt-startvm')
def _start_vm(self, cmd):
try:
vm = get_vm_by_uuid_no_retry(cmd.vmInstanceUuid, False)
if vm:
if vm.state == Vm.VM_STATE_RUNNING:
raise kvmagent.KvmError(
'vm[uuid:%s, name:%s] is already running' % (cmd.vmInstanceUuid, vm.get_name()))
else:
vm.destroy()
vm = Vm.from_StartVmCmd(cmd)
vm.start(cmd.timeout)
except libvirt.libvirtError as e:
logger.warn(linux.get_exception_stacktrace())
if "Device or resource busy" in str(e.message):
raise kvmagent.KvmError(
'unable to start vm[uuid:%s, name:%s], libvirt error: %s' % (
cmd.vmInstanceUuid, cmd.vmName, str(e)))
try:
vm = get_vm_by_uuid(cmd.vmInstanceUuid)
if vm and vm.state != Vm.VM_STATE_RUNNING:
raise kvmagent.KvmError(
'vm[uuid:%s, name:%s, state:%s] is not in running state, libvirt error: %s' % (
cmd.vmInstanceUuid, cmd.vmName, vm.state, str(e)))
except kvmagent.KvmError:
raise kvmagent.KvmError(
'unable to start vm[uuid:%s, name:%s], libvirt error: %s' % (cmd.vmInstanceUuid, cmd.vmName, str(e)))关键逻辑：
vm = Vm.from_StartVmCmd(cmd)
vm.start(cmd.timeout)先看from_StartVmCmd
@staticmethod
def from_StartVmCmd(cmd):
use_virtio = cmd.useVirtio
use_numa = cmd.useNuma
elements = {}
def make_root():
root = etree.Element('domain')
root.set('type', 'kvm')
# self._root.set('type', 'qemu')
root.set('xmlns:qemu', 'http://libvirt.org/schemas/domain/qemu/1.0')
elements['root'] = root
def make_cpu():
if use_numa:
root = elements['root']
e(root, 'vcpu', '128', {'placement': 'static', 'current': str(cmd.cpuNum)})
# e(root,'vcpu',str(cmd.cpuNum),{'placement':'static'})
tune = e(root, 'cputune')
e(tune, 'shares', str(cmd.cpuSpeed * cmd.cpuNum))
# enable nested virtualization
if cmd.nestedVirtualization == 'host-model':
cpu = e(root, 'cpu', attrib={'mode': 'host-model'})
e(cpu, 'model', attrib={'fallback': 'allow'})
elif cmd.nestedVirtualization == 'host-passthrough':
cpu = e(root, 'cpu', attrib={'mode': 'host-passthrough'})
e(cpu, 'model', attrib={'fallback': 'allow'})
elif IS_AARCH64:
cpu = e(root, 'cpu', attrib={'mode': 'host-passthrough'})
e(cpu, 'model', attrib={'fallback': 'allow'})
else:
cpu = e(root, 'cpu')
# e(cpu, 'topology', attrib={'sockets': str(cmd.socketNum), 'cores': str(cmd.cpuOnSocket), 'threads': '1'})
mem = cmd.memory / 1024
e(cpu, 'topology', attrib={'sockets': str(32), 'cores': str(4), 'threads': '1'})
numa = e(cpu, 'numa')
e(numa, 'cell', attrib={'id': '0', 'cpus': '0-127', 'memory': str(mem), 'unit': 'KiB'})
else:
root = elements['root']
# e(root, 'vcpu', '128', {'placement': 'static', 'current': str(cmd.cpuNum)})
e(root, 'vcpu', str(cmd.cpuNum), {'placement': 'static'})
tune = e(root, 'cputune')
e(tune, 'shares', str(cmd.cpuSpeed * cmd.cpuNum))
# enable nested virtualization
if cmd.nestedVirtualization == 'host-model':
cpu = e(root, 'cpu', attrib={'mode': 'host-model'})
e(cpu, 'model', attrib={'fallback': 'allow'})
elif cmd.nestedVirtualization == 'host-passthrough':
cpu = e(root, 'cpu', attrib={'mode': 'host-passthrough'})
e(cpu, 'model', attrib={'fallback': 'allow'})
elif IS_AARCH64:
cpu = e(root, 'cpu', attrib={'mode': 'host-passthrough'})
e(cpu, 'model', attrib={'fallback': 'allow'})
else:
cpu = e(root, 'cpu')
e(cpu, 'topology', attrib={'sockets': str(cmd.socketNum), 'cores': str(cmd.cpuOnSocket), 'threads': '1'})
def make_memory():
root = elements['root']
mem = cmd.memory / 1024
if use_numa:
e(root, 'maxMemory', str(68719476736), {'slots': str(16), 'unit': 'KiB'})
# e(root,'memory',str(mem),{'unit':'k'})
e(root, 'currentMemory', str(mem), {'unit': 'k'})
else:
e(root, 'memory', str(mem), {'unit': 'k'})
e(root, 'currentMemory', str(mem), {'unit': 'k'})
def make_os():
root = elements['root']
os = e(root, 'os')
if IS_AARCH64:
e(os, 'type', 'hvm', attrib={'arch': 'aarch64'})
e(os, 'loader', '/usr/share/edk2.git/aarch64/QEMU_EFI-pflash.raw', attrib={'readonly': 'yes', 'type': 'pflash'})
else:
e(os, 'type', 'hvm', attrib={'machine': 'pc'})
# if not booting from cdrom, don't add any boot element in os section
if cmd.bootDev[0] == "cdrom":
for boot_dev in cmd.bootDev:
e(os, 'boot', None, {'dev': boot_dev})
if cmd.useBootMenu:
e(os, 'bootmenu', attrib={'enable': 'yes'})
def make_features():
root = elements['root']
features = e(root, 'features')
for f in ['acpi', 'apic', 'pae']:
e(features, f)
if cmd.kvmHiddenState == True:
kvm = e(features, "kvm")
e(kvm, 'hidden', None, {'state': 'on'})
def make_devices():
root = elements['root']
devices = e(root, 'devices')
if cmd.addons and cmd.addons['qemuPath']:
e(devices, 'emulator', cmd.addons['qemuPath'])
else:
e(devices, 'emulator', kvmagent.get_qemu_path())
tablet = e(devices, 'input', None, {'type': 'tablet', 'bus': 'usb'})
e(tablet, 'address', None, {'type':'usb', 'bus':'0', 'port':'1'})
if IS_AARCH64:
keyboard = e(devices, 'input', None, {'type': 'keyboard', 'bus': 'usb'})
elements['devices'] = devices
def make_cdrom():
devices = elements['devices']
MAX_CDROM_NUM = len(Vm.ISO_DEVICE_LETTERS)
EMPTY_CDROM_CONFIGS = None
if IS_AARCH64:
# AArch64 Does not support the attachment of multiple iso
EMPTY_CDROM_CONFIGS = [
EmptyCdromConfig(None, None, None)
]
else:
# bus 0 unit 0 already use by root volume
EMPTY_CDROM_CONFIGS = [
EmptyCdromConfig('hd%s' % Vm.ISO_DEVICE_LETTERS[0], '0', '1'),
EmptyCdromConfig('hd%s' % Vm.ISO_DEVICE_LETTERS[1], '1', '0'),
EmptyCdromConfig('hd%s' % Vm.ISO_DEVICE_LETTERS[2], '1', '1')
]
if len(EMPTY_CDROM_CONFIGS) != MAX_CDROM_NUM:
logger.error('ISO_DEVICE_LETTERS or EMPTY_CDROM_CONFIGS config error')
def makeEmptyCdrom(targetDev, bus, unit):
cdrom = e(devices, 'disk', None, {'type': 'file', 'device': 'cdrom'})
e(cdrom, 'driver', None, {'name': 'qemu', 'type': 'raw'})
if IS_AARCH64:
e(cdrom, 'target', None, {'dev': 'sdc', 'bus': 'scsi'})
else:
e(cdrom, 'target', None, {'dev': targetDev, 'bus': 'ide'})
e(cdrom, 'address', None,{'type' : 'drive', 'bus' : bus, 'unit' : unit})
e(cdrom, 'readonly', None)
return cdrom
if not cmd.bootIso:
for config in EMPTY_CDROM_CONFIGS:
makeEmptyCdrom(config.targetDev, config.bus, config.unit)
return
notEmptyCdrom = set([])
for iso in cmd.bootIso:
notEmptyCdrom.add(iso.deviceId)
cdromConfig = EMPTY_CDROM_CONFIGS[iso.deviceId]
if iso.path.startswith('ceph'):
ic = IsoCeph()
ic.iso = iso
devices.append(ic.to_xmlobject(cdromConfig.targetDev, cdromConfig.bus , cdromConfig.unit))
elif iso.path.startswith('fusionstor'):
ic = IsoFusionstor()
ic.iso = iso
devices.append(ic.to_xmlobject(cdromConfig.targetDev, cdromConfig.bus , cdromConfig.unit))
else:
cdrom = makeEmptyCdrom(cdromConfig.targetDev, cdromConfig.bus , cdromConfig.unit)
e(cdrom, 'source', None, {'file': iso.path})
emptyCdrom = set(range(MAX_CDROM_NUM)).difference(notEmptyCdrom)
for i in emptyCdrom:
cdromConfig = EMPTY_CDROM_CONFIGS[i]
makeEmptyCdrom(cdromConfig.targetDev, cdromConfig.bus, cdromConfig.unit)
def make_volumes():
devices = elements['devices']
volumes = [cmd.rootVolume]
volumes.extend(cmd.dataVolumes)
def filebased_volume(_dev_letter, _v):
disk = etree.Element('disk', {'type': 'file', 'device': 'disk', 'snapshot': 'external'})
e(disk, 'driver', None, {'name': 'qemu', 'type': linux.get_img_fmt(_v.installPath), 'cache': _v.cacheMode})
e(disk, 'source', None, {'file': _v.installPath})
if _v.shareable:
e(disk, 'shareable')
if _v.useVirtioSCSI:
e(disk, 'target', None, {'dev': 'sd%s' % _dev_letter, 'bus': 'scsi'})
e(disk, 'wwn', _v.wwn)
e(disk, 'address', None, {'type': 'drive', 'controller': '0', 'unit': str(_v.deviceId)})
return disk
if _v.useVirtio:
e(disk, 'target', None, {'dev': 'vd%s' % _dev_letter, 'bus': 'virtio'})
elif IS_AARCH64:
e(disk, 'target', None, {'dev': 'sd%s' % _dev_letter, 'bus': 'scsi'})
else:
e(disk, 'target', None, {'dev': 'sd%s' % _dev_letter, 'bus': 'ide'})
return disk
def iscsibased_volume(_dev_letter, _v):
def blk_iscsi():
bi = BlkIscsi()
portal, bi.target, bi.lun = _v.installPath.lstrip('iscsi://').split('/')
bi.server_hostname, bi.server_port = portal.split(':')
bi.device_letter = _dev_letter
bi.volume_uuid = _v.volumeUuid
bi.chap_username = _v.chapUsername
bi.chap_password = _v.chapPassword
return bi.to_xmlobject()
def virtio_iscsi():
vi = VirtioIscsi()
portal, vi.target, vi.lun = _v.installPath.lstrip('iscsi://').split('/')
vi.server_hostname, vi.server_port = portal.split(':')
vi.device_letter = _dev_letter
vi.volume_uuid = _v.volumeUuid
vi.chap_username = _v.chapUsername
vi.chap_password = _v.chapPassword
return vi.to_xmlobject()
if _v.useVirtio:
return virtio_iscsi()
else:
return blk_iscsi()
def ceph_volume(_dev_letter, _v):
def ceph_virtio():
vc = VirtioCeph()
vc.volume = _v
vc.dev_letter = _dev_letter
return vc.to_xmlobject()
def ceph_blk():
if not IS_AARCH64:
ic = IdeCeph()
else:
ic = ScsiCeph()
ic.volume = _v
ic.dev_letter = _dev_letter
return ic.to_xmlobject()
def ceph_virtio_scsi():
vsc = VirtioSCSICeph()
vsc.volume = _v
vsc.dev_letter = _dev_letter
return vsc.to_xmlobject()
if _v.useVirtioSCSI:
disk = ceph_virtio_scsi()
if _v.shareable:
e(disk, 'shareable')
return disk
if _v.useVirtio:
return ceph_virtio()
else:
return ceph_blk()
def fusionstor_volume(_dev_letter, _v):
def fusionstor_virtio():
vc = VirtioFusionstor()
vc.volume = _v
vc.dev_letter = _dev_letter
return vc.to_xmlobject()
def fusionstor_blk():
ic = IdeFusionstor()
ic.volume = _v
ic.dev_letter = _dev_letter
return ic.to_xmlobject()
def fusionstor_virtio_scsi():
vsc = VirtioSCSIFusionstor()
vsc.volume = _v
vsc.dev_letter = _dev_letter
return vsc.to_xmlobject()
if _v.useVirtioSCSI:
disk = fusionstor_virtio_scsi()
if _v.shareable:
e(disk, 'shareable')
return disk
if _v.useVirtio:
return fusionstor_virtio()
else:
return fusionstor_blk()
def volume_qos(volume_xml_obj):
if not cmd.addons:
return
vol_qos = cmd.addons['VolumeQos']
if not vol_qos:
return
qos = vol_qos[v.volumeUuid]
if not qos:
return
if not qos.totalBandwidth and not qos.totalIops:
return
iotune = e(volume_xml_obj, 'iotune')
if qos.totalBandwidth:
e(iotune, 'total_bytes_sec', str(qos.totalBandwidth))
if qos.totalIops:
# e(iotune, 'total_iops_sec', str(qos.totalIops))
e(iotune, 'read_iops_sec', str(qos.totalIops))
e(iotune, 'write_iops_sec', str(qos.totalIops))
# e(iotune, 'read_iops_sec_max', str(qos.totalIops))
# e(iotune, 'write_iops_sec_max', str(qos.totalIops))
# e(iotune, 'total_iops_sec_max', str(qos.totalIops))
volumes.sort(key=lambda d: d.deviceId)
scsi_device_ids = [v.deviceId for v in volumes if v.useVirtioSCSI]
for v in volumes:
if v.deviceId >= len(Vm.DEVICE_LETTERS):
err = "exceeds max disk limit, it's %s but only 26 allowed" % v.deviceId
logger.warn(err)
raise kvmagent.KvmError(err)
dev_letter = Vm.DEVICE_LETTERS[v.deviceId]
if v.useVirtioSCSI:
dev_letter = Vm.DEVICE_LETTERS[scsi_device_ids.pop()]
if v.deviceType == 'file':
vol = filebased_volume(dev_letter, v)
elif v.deviceType == 'iscsi':
vol = iscsibased_volume(dev_letter, v)
elif v.deviceType == 'ceph':
vol = ceph_volume(dev_letter, v)
elif v.deviceType == 'fusionstor':
vol = fusionstor_volume(dev_letter, v)
else:
raise Exception('unknown volume deviceType: %s' % v.deviceType)
assert vol is not None, 'vol cannot be None'
# set boot order for root volume when boot from hd
if v.deviceId == 0 and cmd.bootDev[0] == 'hd' and cmd.useBootMenu:
e(vol, 'boot', None, {'order': '1'})
volume_qos(vol)
devices.append(vol)
def make_nics():
if not cmd.nics:
return
def nic_qos(nic_xml_object):
if not cmd.addons:
return
nqos = cmd.addons['NicQos']
if not nqos:
return
qos = nqos[nic.uuid]
if not qos:
return
if not qos.outboundBandwidth and not qos.inboundBandwidth:
return
bandwidth = e(nic_xml_object, 'bandwidth')
if qos.outboundBandwidth:
e(bandwidth, 'outbound', None, {'average': str(qos.outboundBandwidth / 1024 / 8)})
if qos.inboundBandwidth:
e(bandwidth, 'inbound', None, {'average': str(qos.inboundBandwidth / 1024 / 8)})
devices = elements['devices']
for nic in cmd.nics:
interface = e(devices, 'interface', None, {'type': 'bridge'})
e(interface, 'mac', None, {'address': nic.mac})
if nic.ip is not None and nic.ip != "":
filterref = e(interface, 'filterref', None, {'filter':'clean-traffic'})
e(filterref, 'parameter', None, {'name':'IP', 'value': nic.ip})
e(interface, 'alias', None, {'name': 'net%s' % nic.nicInternalName.split('.')[1]})
e(interface, 'source', None, {'bridge': nic.bridgeName})
if use_virtio:
e(interface, 'model', None, {'type': 'virtio'})
else:
e(interface, 'model', None, {'type': 'e1000'})
e(interface, 'target', None, {'dev': nic.nicInternalName})
nic_qos(interface)
def make_meta():
root = elements['root']
e(root, 'name', cmd.vmInstanceUuid)
e(root, 'uuid', uuidhelper.to_full_uuid(cmd.vmInstanceUuid))
e(root, 'description', cmd.vmName)
e(root, 'on_poweroff', 'destroy')
e(root, 'on_crash', 'restart')
e(root, 'on_reboot', 'restart')
meta = e(root, 'metadata')
zs = e(meta, 'zstack', usenamesapce=True)
e(zs, 'internalId', str(cmd.vmInternalId))
e(zs, 'hostManagementIp', str(cmd.hostManagementIp))
clock = e(root, 'clock', None, {'offset': cmd.clock})
if cmd.clock == 'localtime':
e(clock, 'timer', None, {'name': 'rtc', 'tickpolicy': 'catchup'})
e(clock, 'timer', None, {'name': 'pit', 'tickpolicy': 'delay'})
e(clock, 'timer', None, {'name': 'hpet', 'present': 'no'})
e(clock, 'timer', None, {'name': 'hypervclock', 'present': 'yes'})
def make_vnc():
devices = elements['devices']
if cmd.consolePassword == None:
vnc = e(devices, 'graphics', None, {'type': 'vnc', 'port': '5900', 'autoport': 'yes'})
else:
vnc = e(devices, 'graphics', None,
{'type': 'vnc', 'port': '5900', 'autoport': 'yes', 'passwd': str(cmd.consolePassword)})
e(vnc, "listen", None, {'type': 'address', 'address': '0.0.0.0'})
def make_spice():
devices = elements['devices']
spice = e(devices, 'graphics', None, {'type': 'spice', 'port': '5900', 'autoport': 'yes'})
e(spice, "listen", None, {'type': 'address', 'address': '0.0.0.0'})
e(spice, "image", None, {'compression': 'auto_glz'})
e(spice, "jpeg", None, {'compression': 'always'})
e(spice, "zlib", None, {'compression': 'never'})
e(spice, "playback", None, {'compression': 'off'})
e(spice, "streaming", None, {'mode': cmd.spiceStreamingMode})
e(spice, "mouse", None, {'mode': 'client'})
e(spice, "filetransfer", None, {'enable': 'no'})
e(spice, "clipboard", None, {'copypaste': 'no'})
def make_usb_redirect():
if cmd.usbRedirect == "true":
devices = elements['devices']
e(devices, 'controller', None, {'type': 'usb', 'model': 'ich9-ehci1'})
e(devices, 'controller', None, {'type': 'usb', 'model': 'ich9-uhci1', 'multifunction': 'on'})
e(devices, 'controller', None, {'type': 'usb', 'model': 'ich9-uhci2'})
e(devices, 'controller', None, {'type': 'usb', 'model': 'ich9-uhci3'})
chan = e(devices, 'channel', None, {'type': 'spicevmc'})
e(chan, 'target', None, {'type': 'virtio', 'name': 'com.redhat.spice.0'})
e(chan, 'address', None, {'type': 'virtio-serial'})
redirdev2 = e(devices, 'redirdev', None, {'type': 'spicevmc', 'bus': 'usb'})
e(redirdev2, 'address', None, {'type': 'usb', 'bus': '0', 'port': '2'})
redirdev3 = e(devices, 'redirdev', None, {'type': 'spicevmc', 'bus': 'usb'})
e(redirdev3, 'address', None, {'type': 'usb', 'bus': '0', 'port': '3'})
redirdev4 = e(devices, 'redirdev', None, {'type': 'spicevmc', 'bus': 'usb'})
e(redirdev4, 'address', None, {'type': 'usb', 'bus': '0', 'port': '4'})
redirdev5 = e(devices, 'redirdev', None, {'type': 'spicevmc', 'bus': 'usb'})
e(redirdev5, 'address', None, {'type': 'usb', 'bus': '0', 'port': '6'})
else:
# make sure there are three default usb controllers, for usb 1.1/2.0/3.0
devices = elements['devices']
e(devices, 'controller', None, {'type': 'usb', 'index': '0'})
if not IS_AARCH64:
e(devices, 'controller', None, {'type': 'usb', 'index': '1', 'model': 'ehci'})
e(devices, 'controller', None, {'type': 'usb', 'index': '2', 'model': 'nec-xhci'})
def make_video():
devices = elements['devices']
if IS_AARCH64:
video = e(devices, 'video')
e(video, 'model', None, {'type': 'virtio'})
elif cmd.videoType != "qxl":
video = e(devices, 'video')
e(video, 'model', None, {'type': str(cmd.videoType)})
else:
for monitor in range(cmd.VDIMonitorNumber):
video = e(devices, 'video')
e(video, 'model', None, {'type': str(cmd.videoType)})
def make_audio_microphone():
if cmd.consoleMode == 'spice':
devices = elements['devices']
e(devices, 'sound',None,{'model':'ich6'})
else:
return
def make_graphic_console():
if cmd.consoleMode == 'spice':
make_spice()
else:
make_vnc()
def make_addons():
if not cmd.addons:
return
devices = elements['devices']
channel = cmd.addons['channel']
if channel:
basedir = os.path.dirname(channel.socketPath)
linux.mkdir(basedir, 0777)
chan = e(devices, 'channel', None, {'type': 'unix'})
e(chan, 'source', None, {'mode': 'bind', 'path': channel.socketPath})
e(chan, 'target', None, {'type': 'virtio', 'name': channel.targetName})
cephSecretKey = cmd.addons['ceph_secret_key']
cephSecretUuid = cmd.addons['ceph_secret_uuid']
if cephSecretKey and cephSecretUuid:
VmPlugin._create_ceph_secret_key(cephSecretKey, cephSecretUuid)
pciDevices = cmd.addons['pciDevice']
if pciDevices:
make_pci_device(pciDevices)
usbDevices = cmd.addons['usbDevice']
if usbDevices:
make_usb_device(usbDevices)
def make_pci_device(addresses):
devices = elements['devices']
for addr in addresses:
if match_pci_device(addr):
hostdev = e(devices, "hostdev", None, {'mode': 'subsystem', 'type': 'pci', 'managed': 'yes'})
e(hostdev, "driver", None, {'name': 'vfio'})
source = e(hostdev, "source")
e(source, "address", None, {
"domain": hex(0) if len(addr.split(":")) == 2 else hex(int(addr.split(":")[0], 16)),
"bus": hex(int(addr.split(":")[-2], 16)),
"slot": hex(int(addr.split(":")[-1].split(".")[0], 16)),
"function": hex(int(addr.split(":")[-1].split(".")[1], 16))
})
else:
raise kvmagent.KvmError(
'can not find pci device for address %s' % addr)
def make_usb_device(usbDevices):
next_uhci_port = 2
next_ehci_port = 1
next_xhci_port = 1
devices = elements['devices']
for usb in usbDevices:
if match_usb_device(usb):
hostdev = e(devices, "hostdev", None, {'mode': 'subsystem', 'type': 'usb', 'managed': 'yes'})
source = e(hostdev, "source")
e(source, "address", None, {
"bus": str(int(usb.split(":")[0])),
"device": str(int(usb.split(":")[1]))
})
e(source, "vendor", None, {
"id": hex(int(usb.split(":")[2], 16))
})
e(source, "product", None, {
"id": hex(int(usb.split(":")[3], 16))
})
# get controller index from usbVersion
# eg. 1.1 -> 0
# eg. 2.0.0 -> 1
# eg. 3 -> 2
bus = int(usb.split(":")[4][0]) - 1
if bus == 0:
address = e(hostdev, "address", None, {'type': 'usb', 'bus': str(bus), 'port': str(next_uhci_port)})
next_uhci_port += 1
elif bus == 1:
address = e(hostdev, "address", None, {'type': 'usb', 'bus': str(bus), 'port': str(next_ehci_port)})
next_ehci_port += 1
elif bus == 2:
address = e(hostdev, "address", None, {'type': 'usb', 'bus': str(bus), 'port': str(next_xhci_port)})
next_xhci_port += 1
else:
raise kvmagent.KvmError('unknown usb controller %s', bus)
else:
raise kvmagent.KvmError('cannot find usb device %s', usb)
# TODO(WeiW) Validate here
def match_pci_device(addr):
return True
def match_usb_device(addr):
if len(addr.split(':')) == 5:
return True
else:
return False
def make_balloon_memory():
devices = elements['devices']
b = e(devices, 'memballoon', None, {'model': 'virtio'})
e(b, 'stats', None, {'period': '10'})
def make_console():
devices = elements['devices']
serial = e(devices, 'serial', None, {'type': 'pty'})
e(serial, 'target', None, {'port': '0'})
console = e(devices, 'console', None, {'type': 'pty'})
e(console, 'target', None, {'type': 'serial', 'port': '0'})
def make_sec_label():
root = elements['root']
e(root, 'seclabel', None, {'type': 'none'})
def make_controllers():
devices = elements['devices']
e(devices, 'controller', None, {'type': 'scsi', 'model': 'virtio-scsi'})
make_root()
make_meta()
make_cpu()
make_memory()
make_os()
make_features()
make_devices()
make_video()
make_audio_microphone()
make_nics()
make_volumes()
make_cdrom()
make_graphic_console()
make_usb_redirect()
make_addons()
make_balloon_memory()
make_console()
make_sec_label()
make_controllers()
root = elements['root']
xml = etree.tostring(root)
vm = Vm()
vm.uuid = cmd.vmInstanceUuid
vm.domain_xml = xml
vm.domain_xmlobject = xmlobject.loads(xml)
return vm显然，上述逻辑是在组装一份xml，便于之后的libvirt使用。
然后是
vm.start(cmd.timeout)可以看到，这里是直接调用了libvirt的sdk。
这仅仅是一个调用流程。而在很多地方，来自MN的请求会直接调用linux的shell命令，详情见linux.py。（获取云盘大小、主存储容量等）。
问题
在基于扩展ZStack的Agent时，如果是一个全新的功能模块，可能并不会造成和原有代码的深度耦合。但如果在原有功能上的增强， 对原有代码进行修改可能会导致我们的业务逻辑和Utility的上游代码耦合。而在没有足够人力来维护、开发ZStack时，我们会将目标定为能够及时跟上发布版本。 因此，我们要尽量减少冲突。
举个例子：我们要对启动vm的逻辑进行增强，添加一个自己的配置写入xml。这段代码如果写进了vm_plugin.py，那么就是一个耦合。耦合多了以后，跟上发布版本就会很困难。
解决方案
这是一个参考方案：
如果是引入一个全新的功能模块，建议重写一个项目。无论是代码规范还是自动化测试，都可以有一个很好的实践。
如果是基于Utility的扩展，比如对于扩展的api——APIStartVmInstanceExMsg。由上游发送http request时，将指定v2版本的agent。比如原有start vm会发送至path：AGENT_IP:7070/vm/start；而如果我们增强了这部分逻辑，将这段代码copy至vm_plugin_ex.py，并注册一个path，ex/vm/start。当然port也要重新注册一个，就像这样：：AGENT_IP:7071/ex/vm/start。
同样的，对linux.py扩展时，复制一个linux2.py来存放属于我们自己的扩展逻辑。