213 lines
7.2 KiB
Python
213 lines
7.2 KiB
Python
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from pathlib import Path
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from lxml.builder import E
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from lxml.etree import Element, QName, SubElement, tostring, fromstring
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XPATH_DOM_NAME = '/domain/name'
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XPATH_DOM_TITLE = '/domain/title'
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XPATH_DOM_DESCRIPTION = '/domain/description'
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XPATH_DOM_METADATA = '/domain/metadata'
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XPATH_DOM_MEMORY = '/domain/memory'
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XPATH_DOM_CURRENT_MEMORY = '/domain/currentMemory'
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XPATH_DOM_VCPU = '/domain/vcpu'
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XPATH_DOM_OS = '/domian/os'
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XPATH_DOM_CPU = '/domain/cpu'
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class Reader:
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def __init__(xml: str):
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self.xml = xml
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self.el = fromstring(self.xml)
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def get_domcaps_machine(self):
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return self.el.xpath('/domainCapabilities/machine')[0].text
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def get_domcaps_cpus(self):
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# mode can be: custom, host-model, host-passthrough
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return self.el.xpath('/domainCapabilities/cpu/mode[@name="custom"]')[0]
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class Constructor:
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"""
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The XML constructor. This class builds XML configs for libvirt.
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Features:
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- Generate basic virtual machine XML. See gen_domain_xml()
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- Generate virtual disk XML. See gen_volume_xml()
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- Add arbitrary metadata to XML from special structured dict
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"""
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def __init__(self, xml: str | None = None):
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self.xml_string = xml
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self.xml = None
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@property
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def domain_xml(self):
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return self.xml
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def gen_domain_xml(self,
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name: str,
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title: str,
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vcpus: int,
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vcpu_vendor: str,
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vcpu_model: str,
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mac_addr: str,
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memory: int,
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volume: Path,
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vcpu_features: dict | None = None,
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desc: str = "") -> None:
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"""
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Generate default domain XML configuration for virtual machines.
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See https://lxml.de/tutorial.html#the-e-factory for details.
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"""
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domain_xml = E.domain(
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E.name(name),
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E.title(title),
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E.description(desc),
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E.metadata(),
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E.memory(str(memory), unit='MB'),
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E.currentMemory(str(memory), unit='MB'),
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E.vcpu(str(vcpus), placement='static'),
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E.os(
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E.type('hvm', arch='x86_64'),
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E.boot(dev='cdrom'),
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E.boot(dev='hd'),
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),
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E.features(
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E.acpi(),
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E.apic(),
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),
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E.cpu(
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E.vendor(vcpu_vendor),
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E.model(vcpu_model, fallback='forbid'),
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E.topology(sockets='1', dies='1', cores=str(vcpus),
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threads='1'),
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mode='custom',
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match='exact',
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check='partial',
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),
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E.on_poweroff('destroy'),
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E.on_reboot('restart'),
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E.on_crash('restart'),
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E.pm(
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E('suspend-to-mem', enabled='no'),
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E('suspend-to-disk', enabled='no'),
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),
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E.devices(
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E.emulator('/usr/bin/qemu-system-x86_64'),
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E.disk(
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E.driver(name='qemu', type='qcow2', cache='writethrough'),
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E.source(file=volume),
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E.target(dev='vda', bus='virtio'),
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type='file',
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device='disk',
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),
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E.interface(
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E.source(network='default'),
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E.mac(address=mac_addr),
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type='network',
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),
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E.graphics(
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E.listen(type='address'),
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type='vnc', port='-1', autoport='yes'
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),
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E.video(
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E.model(type='vga', vram='16384', heads='1', primary='yes'),
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E.address(type='pci', domain='0x0000', bus='0x00',
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slot='0x02', function='0x0'),
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),
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),
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type='kvm',
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)
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return self.to_string(domain_xml)
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def gen_volume_xml(self,
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device_name: str,
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file: Path,
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bus: str = 'virtio',
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cache: str = 'writethrough',
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disktype: str = 'file'):
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disk_xml = E.disk(E.driver(name='qemu', type='qcow2', cache=cache),
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E.source(file=file),
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E.target(dev=device_name, bus=bus),
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type=disktype,
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device='disk')
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return self.to_string(disk_xml)
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def add_volume(self):
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raise NotImplementedError()
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def add_meta(self, data: dict, namespace: str, nsprefix: str) -> None:
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"""
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Add metadata to domain. See:
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https://libvirt.org/formatdomain.html#general-metadata
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"""
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metadata = metadata_old = self.xml.xpath('/domain/metadata')[0]
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metadata.append(
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self.construct_xml(
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data,
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namespace=namespace,
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nsprefix=nsprefix,
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))
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self.xml.replace(metadata_old, metadata)
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def remove_meta(self, namespace: str):
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"""Remove metadata by namespace."""
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raise NotImplementedError()
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def construct_xml(self,
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tag: dict,
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namespace: str | None = None,
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nsprefix: str | None = None,
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root: Element = None) -> Element:
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"""
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Shortly this recursive function transforms dictonary to XML.
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Return etree.Element built from dict with following structure::
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{
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'name': 'device', # tag name
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'text': '', # optional key
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'values': { # optional key, must be a dict of key-value pairs
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'type': 'disk'
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},
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children: [] # optional key, must be a list of dicts
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}
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Child elements must have the same structure. Infinite `children` nesting
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is allowed.
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"""
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use_ns = False
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if isinstance(namespace, str) and isinstance(nsprefix, str):
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use_ns = True
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# Create element
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if root is None:
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if use_ns:
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element = Element(QName(namespace, tag['name']),
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nsmap={nsprefix: namespace})
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else:
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element = Element(tag['name'])
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else:
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if use_ns:
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element = SubElement(root, QName(namespace, tag['name']))
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else:
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element = SubElement(root, tag['name'])
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# Fill up element with content
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if 'text' in tag.keys():
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element.text = tag['text']
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if 'values' in tag.keys():
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for key in tag['values'].keys():
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element.set(str(key), str(tag['values'][key]))
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if 'children' in tag.keys():
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for child in tag['children']:
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element.append(
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self.construct_xml(child,
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namespace=namespace,
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nsprefix=nsprefix,
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root=element))
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return element
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def to_string(self):
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return (tostring(self.xml, pretty_print=True,
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encoding='utf-8').decode().strip())
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