mirror of
https://github.com/retspen/webvirtcloud
synced 2026-11-09 19:56:48 +00:00
refactor(instances): live clone primitives and a shared clone definition
The clone's definition is one method for both paths; wvmInstance can check, start, follow, read and abort a push backup of a VM's disks into new volumes, and freeze/thaw the guest.
This commit is contained in:
catborise
parent
27dfc1407f
commit
39ad472a7c
2 changed files with 477 additions and 62 deletions
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@ -40,6 +40,12 @@ try:
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VIR_ERR_OPERATION_INVALID,
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VIR_DOMAIN_SNAPSHOT_LIST_INTERNAL,
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VIR_DOMAIN_SNAPSHOT_LIST_EXTERNAL,
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VIR_DOMAIN_BACKUP_BEGIN_REUSE_EXTERNAL,
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VIR_DOMAIN_JOB_NONE,
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VIR_DOMAIN_JOB_OPERATION_BACKUP,
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VIR_DOMAIN_JOB_STATS_COMPLETED,
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VIR_DOMAIN_JOB_STATS_KEEP_COMPLETED,
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VIR_ERR_NO_DOMAIN_BACKUP,
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libvirtError,
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)
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from libvirt_qemu import VIR_DOMAIN_QEMU_AGENT_COMMAND_DEFAULT, qemuAgentCommand
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@ -65,6 +71,12 @@ PERSISTENT_XML = VIR_DOMAIN_XML_INACTIVE | VIR_DOMAIN_XML_SECURE
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SNAPSHOT_NAME = re.compile(r"[A-Za-z0-9_-][A-Za-z0-9._-]{0,63}")
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# the longest window wvmInstance.usage() averages over
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USAGE_MAX_WINDOW = 30
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# A running VM is cloned with a push backup that keeps the VM alive when the
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# guest shuts down during the copy: libvirt 11.10.
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LIVE_CLONE_MIN_LIBVIRT = 11_010_000
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# libvirt 11.10's value; bindings built against older libvirt lack the name,
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# and the flag is sent to the host, whose version is checked.
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VIR_DOMAIN_BACKUP_BEGIN_PRESERVE_SHUTDOWN_DOMAIN = 2
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def _rate(before, after, seconds, scale=1):
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@ -1894,13 +1906,11 @@ class wvmInstance(wvmConnect):
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mac_tuples = [mac[i : i + n] for i in range(0, len(mac), n)]
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return ":".join(mac_tuples)
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def clone_instance(self, clone_data, uuid):
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"""Copy a shut-off VM, with its disks and UEFI variables (NVRAM).
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Inputs are checked before anything is allocated, and on failure only
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the volumes this call created are removed. Returns the clone's UUID."""
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if self.get_status() != 5:
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# A running guest keeps writing while its disks are copied.
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raise util.OperationError("Shut the VM down before cloning it")
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def _clone_definition(self, clone_data, uuid):
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"""The VM's persistent definition renamed to the clone, with its UUID,
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title, description and MACs; returns it and the (source, dev) of each
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disk to copy. Disks without a source are dropped. Raises before
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anything is allocated."""
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if clone_data["name"] in self.get_instances():
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raise ValueError("An instance with the clone name already exists")
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@ -1941,15 +1951,90 @@ class wvmInstance(wvmConnect):
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raise ValueError(f"No MAC address for network interface {num}")
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net.find("mac").set("address", self.fix_mac(mac))
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nvram = tree.find("os/nvram")
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if nvram is not None and nvram.get("type", "file") != "file":
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raise util.OperationError("Cannot clone a VM whose NVRAM is not a file")
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return tree, disks
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def _clone_volume_xml(self, name, capacity, vol_format, owner_uid, owner_gid):
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return f"""<volume>
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<name>{util.xml_escape(name)}</name>
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<capacity>{capacity}</capacity>
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<allocation>0</allocation>
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<target>
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<format type='{vol_format}'/>
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<permissions>
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<owner>{owner_uid}</owner>
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<group>{owner_gid}</group>
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<mode>0644</mode>
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<label>virt_image_t</label>
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</permissions>
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<compat>1.1</compat>
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<features><lazy_refcounts/></features>
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</target>
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</volume>"""
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def define_clone(self, clone_data, uuid, paths):
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"""Defines the clone with each copied disk's source set from paths
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({dev: new path}) and its own copy of the VM's UEFI variables (NVRAM).
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The NVRAM copy is removed if the definition fails. Returns the
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clone's UUID."""
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tree, disks = self._clone_definition(clone_data, uuid)
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for source, dev in disks:
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source.set("file" if source.get("file") else "dev" if source.get("dev") else "name", paths[dev])
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# the UEFI variables: a path as text, or a <source file=...> since libvirt 8.5
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nvram = tree.find("os/nvram")
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nvram_source = nvram.find("source") if nvram is not None else None
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nvram_path = None
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if nvram is not None:
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if nvram.get("type", "file") != "file":
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raise util.OperationError("Cannot clone a VM whose NVRAM is not a file")
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nvram_path = nvram_source.get("file") if nvram_source is not None else (nvram.text or "").strip()
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if not nvram_path:
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return self._defineXML(etree.tostring(tree).decode()).UUIDString()
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# the clone starts with the VM's UEFI variables: boot entries, enrolled keys
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if os.path.dirname(nvram_path) == NVRAM_DIR:
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pools = self._nvram_pool()
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else: # a volume of a pool; libvirtError when no pool holds it
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pools = contextlib.nullcontext(self.get_volume_by_path(nvram_path).storagePoolLookupByVolume())
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with pools as pool:
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original = pool.storageVolLookupByName(os.path.basename(nvram_path))
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# same format, owner and mode as the original: the domain names the format,
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# and qemu may run without libvirt changing the file's owner
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target = etree.fromstring(original.XMLDesc(0)).find("target")
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volume = etree.Element("volume")
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etree.SubElement(volume, "name").text = clone_data["name"] + "_VARS" + os.path.splitext(nvram_path)[1]
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etree.SubElement(volume, "capacity").text = "0"
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copy_target = etree.SubElement(volume, "target")
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for tag in ("format", "permissions"):
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if target.find(tag) is not None:
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copy_target.append(target.find(tag))
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copy = pool.createXMLFrom(etree.tostring(volume).decode(), original, 0)
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if nvram_source is not None:
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nvram_source.set("file", copy.path())
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else:
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nvram.text = copy.path()
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try:
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return self._defineXML(etree.tostring(tree).decode()).UUIDString()
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except Exception as err:
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try:
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copy.delete(0)
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except libvirtError:
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raise util.OperationError(
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f"Clone failed ({err}); remove these copies by hand: {copy.path()}"
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) from err
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raise
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def clone_instance(self, clone_data, uuid):
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"""Copy a shut-off VM, with its disks and UEFI variables (NVRAM).
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Inputs are checked before anything is allocated, and on failure only
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the volumes this call created are removed. Returns the clone's UUID."""
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if self.get_status() != 5:
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# A running guest keeps writing while its disks are copied.
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raise util.OperationError("Shut the VM down before cloning it")
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_, disks = self._clone_definition(clone_data, uuid)
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paths = {} # dev: path of its copy
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created = [] # paths of volumes this call created
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try:
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for source, dev in disks:
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@ -1959,27 +2044,14 @@ class wvmInstance(wvmConnect):
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vol = self.get_volume_by_path(source.get("file"))
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vol_format = util.get_xml_path(vol.XMLDesc(0), "/volume/target/format/@type")
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new_vol = vol.storagePoolLookupByVolume().createXMLFrom(
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f"""<volume>
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<name>{target_file}</name>
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<capacity>0</capacity>
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<allocation>0</allocation>
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<target>
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<format type='{vol_format}'/>
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<permissions>
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<owner>{clone_data['disk_owner_uid']}</owner>
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<group>{clone_data['disk_owner_gid']}</group>
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<mode>0644</mode>
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<label>virt_image_t</label>
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</permissions>
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<compat>1.1</compat>
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<features><lazy_refcounts/></features>
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</target>
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</volume>""",
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self._clone_volume_xml(
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target_file, 0, vol_format, clone_data["disk_owner_uid"], clone_data["disk_owner_gid"]
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),
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vol,
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meta_prealloc and vol_format == "qcow2",
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)
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created.append(new_vol.path())
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source.set("file", new_vol.path())
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paths[dev] = new_vol.path()
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elif source.get("protocol") == "rbd":
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vol = self.get_volume_by_path(source.get("name"))
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vol_format = util.get_xml_path(vol.XMLDesc(0), "/volume/target/format/@type")
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@ -1994,7 +2066,7 @@ class wvmInstance(wvmConnect):
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meta_prealloc,
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)
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created.append(new_vol.path())
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source.set("name", f"{os.path.dirname(source.get('name'))}/{target_file}")
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paths[dev] = f"{os.path.dirname(source.get('name'))}/{target_file}"
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else:
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vol = self.get_volume_by_path(source.get("dev"))
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pool_name = util.get_xml_path(vol.storagePoolLookupByVolume().XMLDesc(0), "/pool/name")
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@ -2002,41 +2074,9 @@ class wvmInstance(wvmConnect):
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name = storage.clone_volume(vol.name(), target_file)
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new_path = storage.get_volume(name).path()
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created.append(new_path)
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source.set("dev", new_path)
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paths[dev] = new_path
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if not nvram_path:
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clone = self._defineXML(etree.tostring(tree).decode())
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else:
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# the clone starts with the VM's UEFI variables: boot entries, enrolled keys
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if os.path.dirname(nvram_path) == NVRAM_DIR:
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pools = self._nvram_pool()
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else: # a volume of a pool; libvirtError when no pool holds it
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pools = contextlib.nullcontext(self.get_volume_by_path(nvram_path).storagePoolLookupByVolume())
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with pools as pool:
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original = pool.storageVolLookupByName(os.path.basename(nvram_path))
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# same format, owner and mode as the original: the domain names the format,
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# and qemu may run without libvirt changing the file's owner
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target = etree.fromstring(original.XMLDesc(0)).find("target")
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volume = etree.Element("volume")
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etree.SubElement(volume, "name").text = clone_data["name"] + "_VARS" + os.path.splitext(nvram_path)[1]
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etree.SubElement(volume, "capacity").text = "0"
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copy_target = etree.SubElement(volume, "target")
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for tag in ("format", "permissions"):
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if target.find(tag) is not None:
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copy_target.append(target.find(tag))
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copy = pool.createXMLFrom(etree.tostring(volume).decode(), original, 0)
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if nvram_source is not None:
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nvram_source.set("file", copy.path())
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else:
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nvram.text = copy.path()
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try:
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clone = self._defineXML(etree.tostring(tree).decode())
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except Exception:
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try:
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copy.delete(0)
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except libvirtError:
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created.append(copy.path())
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raise
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return self.define_clone(clone_data, uuid, paths)
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except Exception as err:
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leftovers = []
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for path in reversed(created):
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@ -2048,7 +2088,119 @@ class wvmInstance(wvmConnect):
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raise util.OperationError(f"Clone failed ({err}); remove these copies by hand: {', '.join(leftovers)}") from err
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raise
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return clone.UUIDString()
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def live_clone_targets(self, clone_data, free_percent, free_min_gib):
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"""Refuses a live clone that cannot work, before anything is
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allocated; returns the new volume of each copied disk, in disk order:
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in the source volume's pool, at its virtual capacity and format. Each
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pool keeps the copies plus free_percent of them, at least
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free_min_gib GiB, free (the snapshots' rule); checked only, nothing
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is reserved."""
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if self.wvm.getLibVersion() < LIVE_CLONE_MIN_LIBVIRT:
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raise util.OperationError("Live clone needs libvirt 11.10 or later; shut the VM down to clone it")
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tree, disks = self._clone_definition(clone_data, "")
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if tree.find("devices/tpm") is not None:
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raise util.OperationError("A VM with a TPM is cloned only shut down")
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for source, dev in disks:
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if not source.get("file"):
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raise util.OperationError(f"Disk {dev} is not a local file; shut the VM down to clone it")
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if source.getparent().find("shareable") is not None:
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raise util.OperationError(f"Disk {dev} is shareable; shut the VM down to clone it")
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if self.instance.jobInfo()[0] != VIR_DOMAIN_JOB_NONE:
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raise util.OperationError("Another job is running on the VM; clone it when that ends")
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targets, pools, copied = [], {}, {}
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for source, dev in disks:
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vol = self.get_volume_by_path(source.get("file"))
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pool = vol.storagePoolLookupByVolume()
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name = clone_data["disk-" + dev]
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try:
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pool.storageVolLookupByName(name)
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except libvirtError as err:
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if err.get_error_code() != VIR_ERR_NO_STORAGE_VOL:
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raise
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else:
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raise util.OperationError(f"Volume {name} already exists in storage pool {pool.name()}")
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capacity = vol.info()[1]
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pools[pool.name()] = pool
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copied[pool.name()] = copied.get(pool.name(), 0) + capacity
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targets.append(
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{
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"dev": dev,
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"pool": pool.name(),
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"name": name,
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"path": os.path.join(util.get_xml_path(pool.XMLDesc(0), "/pool/target/path"), name),
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"capacity": capacity,
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"format": util.get_xml_path(vol.XMLDesc(0), "/volume/target/format/@type"),
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}
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)
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for name, size in copied.items():
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needed = size + max(size * free_percent / 100, free_min_gib * 1024**3)
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free = pools[name].info()[3]
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if free < needed:
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raise util.OperationError(
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f"Storage pool {name} has {free / 1024**3:.1f} GiB free; the clone needs {needed / 1024**3:.1f} GiB "
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f"(the copied disks, plus {free_percent:g}% of them, at least {free_min_gib:g} GiB)"
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)
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return targets
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def create_clone_target(self, target, owner_uid, owner_gid):
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"""An empty volume for a copied disk; libvirt refuses one that exists.
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Returns its path."""
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pool = self.wvm.storagePoolLookupByName(target["pool"])
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xml = self._clone_volume_xml(target["name"], target["capacity"], target["format"], owner_uid, owner_gid)
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return pool.createXML(xml, 0).path()
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def begin_clone_backup(self, targets):
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"""Starts libvirt's push backup of the targets' disks into their
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volumes. The VM keeps running when the guest shuts down meanwhile."""
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disks = "".join(
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f"<disk name='{util.xml_escape(t['dev'])}' backup='yes' type='file'>"
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f"<target file='{util.xml_escape(t['path'])}'/><driver type='{util.xml_escape(t['format'])}'/></disk>"
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for t in targets
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)
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self.instance.backupBegin(
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f"<domainbackup mode='push'><disks>{disks}</disks></domainbackup>",
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None,
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VIR_DOMAIN_BACKUP_BEGIN_REUSE_EXTERNAL | VIR_DOMAIN_BACKUP_BEGIN_PRESERVE_SHUTDOWN_DOMAIN,
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)
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def backup_targets(self):
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"""The target paths of the running backup; None when none runs."""
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try:
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xml = self.instance.backupGetXMLDesc(0)
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except libvirtError as err:
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if err.get_error_code() == VIR_ERR_NO_DOMAIN_BACKUP:
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return None
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raise
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return set(etree.fromstring(xml).xpath("disks/disk/target/@file"))
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def backup_progress(self):
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"""(bytes copied, bytes to copy) of the running backup; None when
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none runs."""
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stats = self.instance.jobStats(0)
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if (
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stats.get("type", VIR_DOMAIN_JOB_NONE) == VIR_DOMAIN_JOB_NONE
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or stats.get("operation") != VIR_DOMAIN_JOB_OPERATION_BACKUP
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):
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return None
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return stats.get("disk_processed", 0), stats.get("disk_total", 0)
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def backup_result(self):
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"""(success, libvirt's error) of the completed backup, kept for later
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reads; None when libvirt has no completed backup."""
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stats = self.instance.jobStats(VIR_DOMAIN_JOB_STATS_COMPLETED | VIR_DOMAIN_JOB_STATS_KEEP_COMPLETED)
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if stats.get("operation") != VIR_DOMAIN_JOB_OPERATION_BACKUP or "success" not in stats:
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return None
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return bool(stats["success"]), stats.get("errmsg") or ""
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def abort_backup(self):
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self.instance.abortJob()
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def fs_freeze(self):
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self.instance.fsFreeze(None, 0)
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def fs_thaw(self):
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self.instance.fsThaw(None, 0)
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def add_network(
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self, mac_address, source, source_type="net", model="virtio", nwfilter=None
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