Sys::Virt - Represent and manage a libvirt hypervisor connection

  my $vmm = Sys::Virt->new(address => $addr);

  my @domains = $vmm->list_domains();

  foreach my $dom (@domains) {
    print "Domain ", $dom->get_id, " ", $dom->get_name, "\n";
  }

The Sys::Virt module provides a Perl XS binding to the libvirt virtual machine management APIs. This allows machines running within arbitrary virtualization containers to be managed with a consistent API.

Any operations in the Sys::Virt API which have failure scenarios will result in an instance of the Sys::Virt::Error module being thrown. To catch these errors, simply wrap the method in an eval block. For details of the information contained in the error objects, consult the Sys::Virt::Error manual page.

my $vmm = Sys::Virt->new(uri => $uri, readonly => $ro);

Attach to the virtual machine monitor with the address of address. The uri parameter may be omitted, in which case the default connection made will be to the local Xen hypervisor. Some example URIs include:

xen:///

Xen on the local machine

test:///default

Dummy "in memory" driver for test suites

qemu:///system

System-wide driver for QEMU / KVM virtualization

qemu:///session

Per-user driver for QEMU virtualization

qemu+tls://somehost/system

System-wide QEMU driver on somehost using TLS security

xen+tcp://somehost/

Xen driver on somehost using TCP / SASL security

For further details consult http://libvirt.org/uri.html

If the optional readonly parameter is supplied, then an unprivileged connection to the VMM will be attempted. If it is not supplied, then it defaults to making a fully privileged connection to the VMM. If the calling application is not running as root, it may be necessary to provide authentication callbacks.

If the optional auth parameter is set to a non-zero value, authentication will be enabled during connection, using the default set of credential gathering callbacks. The default callbacks prompt for credentials on the console, so are not suitable for graphical applications. For such apps a custom implementation should be supplied. The credlist parameter should be an array reference listing the set of credential types that will be supported. The credential constants in this module can be used as values in this list. The callback parameter should be a subroutine reference containing the code necessary to gather the credentials. When invoked it will be supplied with a single parameter, a array reference of requested credentials. The elements of the array are hash references, with keys type giving the type of credential, prompt giving a user descriptive user prompt, challenge giving name of the credential required. The answer should be collected from the user, and returned by setting the result key. This key may already be set with a default result if applicable

As a simple example returning hardcoded credentials

    my $address  = "qemu+tcp://192.168.122.1/system";
    my $username = "test";
    my $password = "123456";

    my $con = Sys::Virt->new(address => $address,
                             auth => 1,
                             credlist => [
                               Sys::Virt::CRED_AUTHNAME,
                               Sys::Virt::CRED_PASSPHRASE,
                             ],
                             callback =>
         sub {
               my $creds = shift;

               foreach my $cred (@{$creds}) {
                  if ($cred->{type} == Sys::Virt::CRED_AUTHNAME) {
                      $cred->{result} = $username;
                  }
                  if ($cred->{type} == Sys::Virt::CRED_PASSPHRASE) {
                      $cred->{result} = $password;
                  }
               }
               return 0;
         });

my $st = $vmm->new_stream($flags)

Create a new stream, with the given flags

my $dom = $vmm->create_domain($xml, $flags);

Create a new domain based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Domain class. This method is not available with unprivileged connections to the VMM. The $flags parameter accepts one of the DOMAIN CREATION constants documented in Sys::Virt::Domain, and defaults to 0 if omitted.

my $dom = $vmm->define_domain($xml);

Defines, but does not start, a new domain based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Domain class. This method is not available with unprivileged connections to the VMM. The defined domain can be later started by calling the create method on the returned Sys::Virt::Domain object.

my $dom = $vmm->create_network($xml);

Create a new network based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Network class. This method is not available with unprivileged connections to the VMM.

my $dom = $vmm->define_network($xml);

Defines, but does not start, a new network based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Network class. This method is not available with unprivileged connections to the VMM. The defined network can be later started by calling the create method on the returned Sys::Virt::Network object.

my $dom = $vmm->create_storage_pool($xml);

Create a new storage pool based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::StoragePool class. This method is not available with unprivileged connections to the VMM.

my $dom = $vmm->define_storage_pool($xml);

Defines, but does not start, a new storage pol based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::StoragePool class. This method is not available with unprivileged connections to the VMM. The defined pool can be later started by calling the create method on the returned Sys::Virt::StoragePool object.

my $dom = $vmm->create_interface($xml);

Create a new interface based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Interface class. This method is not available with unprivileged connections to the VMM.

my $dom = $vmm->define_interface($xml);

Defines, but does not start, a new interface based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::Interface class. This method is not available with unprivileged connections to the VMM. The defined interface can be later started by calling the create method on the returned Sys::Virt::Interface object.

my $dom = $vmm->create_node_device($xml);

Create a new virtual node device based on the XML description passed into the $xml parameter. The returned object is an instance of the Sys::Virt::NodeDevice class. This method is not available with unprivileged connections to the VMM.

my @doms = $vmm->list_domains()

Return a list of all domains currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::Domain class.

my $nids = $vmm->num_of_domains()

Return the number of running domains known to the VMM. This can be used as the maxids parameter to list_domain_ids.

my @domIDs = $vmm->list_domain_ids($maxids)

Return a list of all domain IDs currently known to the VMM. The IDs can be used with the get_domain_by_id method.

my @doms = $vmm->list_defined_domains()

Return a list of all domains defined, but not currently running, on the VMM. The elements in the returned list are instances of the Sys::Virt::Domain class.

my $nnames = $vmm->num_of_defined_domains()

Return the number of running domains known to the VMM. This can be used as the maxnames parameter to list_defined_domain_names.

my @names = $vmm->list_defined_domain_names($maxnames)

Return a list of names of all domains defined, but not currently running, on the VMM. The names can be used with the get_domain_by_name method.

my @nets = $vmm->list_networks()

Return a list of all networks currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::Network class.

my $nnames = $vmm->num_of_networks()

Return the number of running networks known to the VMM. This can be used as the maxids parameter to list_network_ids.

my @netNames = $vmm->list_network_names($maxnames)

Return a list of all network names currently known to the VMM. The names can be used with the get_network_by_name method.

my @nets = $vmm->list_defined_networks()

Return a list of all networks defined, but not currently running, on the VMM. The elements in the returned list are instances of the Sys::Virt::Network class.

my $nnamess = $vmm->num_of_defined_networks()

Return the number of running networks known to the host. This can be used as the maxnames parameter to list_defined_network_names.

my @names = $vmm->list_defined_network_names($maxnames)

Return a list of names of all networks defined, but not currently running, on the host. The names can be used with the get_network_by_name method.

my @pools = $vmm->list_storage_pools()

Return a list of all storage pools currently known to the host. The elements in the returned list are instances of the Sys::Virt::StoragePool class.

my $nnames = $vmm->num_of_storage_pools()

Return the number of running storage pools known to the VMM. This can be used as the maxids parameter to list_storage_pool_names.

my @poolNames = $vmm->list_storage_pool_names($maxnames)

Return a list of all storage pool names currently known to the VMM. The IDs can be used with the get_network_by_id method.

my @pools = $vmm->list_defined_storage_pools()

Return a list of all storage pools defined, but not currently running, on the host. The elements in the returned list are instances of the Sys::Virt::StoragePool class.

my $nnames = $vmm->num_of_defined_storage_pools()

Return the number of running networks known to the host. This can be used as the maxnames parameter to list_defined_storage_pool_names.

my @names = $vmm->list_defined_storage_pool_names($maxnames)

Return a list of names of all storage pools defined, but not currently running, on the host. The names can be used with the get_storage_pool_by_name method.

my @devs = $vmm->list_node_devices($capability)

Return a list of all devices currently known to the host OS. The elements in the returned list are instances of the Sys::Virt::NodeDevice class. The optional capability parameter allows the list to be restricted to only devices with a particular capability type.

my $nnames = $vmm->num_of_node_devices($capability[, $flags])

Return the number of host devices known to the VMM. This can be used as the maxids parameter to list_node_device_names. The capability parameter allows the list to be restricted to only devices with a particular capability type, and should be left as undef if the full list is required. The optional <flags> parameter is currently unused and defaults to 0 if omitted.

my @netNames = $vmm->list_node_device_names($capability, $maxnames[, $flags])

Return a list of all host device names currently known to the VMM. The names can be used with the get_node_device_by_name method. The capability parameter allows the list to be restricted to only devices with a particular capability type, and should be left as undef if the full list is required. The optional <flags> parameter is currently unused and defaults to 0 if omitted.

my @ifaces = $vmm->list_interfaces()

Return a list of all network interfaces currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::Interface class.

my $nnames = $vmm->num_of_interfaces()

Return the number of running interfaces known to the VMM. This can be used as the maxnames parameter to list_interface_names.

my @names = $vmm->list_interface_names($maxnames)

Return a list of all interface names currently known to the VMM. The names can be used with the get_interface_by_name method.

my @ifaces = $vmm->list_defined_interfaces()

Return a list of all network interfaces currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::Interface class.

my $nnames = $vmm->num_of_defined_interfaces()

Return the number of inactive interfaces known to the VMM. This can be used as the maxnames parameter to list_defined_interface_names.

my @names = $vmm->list_defined_interface_names($maxnames)

Return a list of inactive interface names currently known to the VMM. The names can be used with the get_interface_by_name method.

my @ifaces = $vmm->list_secrets()

Return a list of all secrets currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::Secret class.

my $nuuids = $vmm->num_of_secrets()

Return the number of secrets known to the VMM. This can be used as the maxuuids parameter to list_secrets.

my @uuids = $vmm->list_secret_uuids($maxuuids)

Return a list of all secret uuids currently known to the VMM. The uuids can be used with the get_secret_by_uuid method.

my @nets = $vmm->list_nwfilters()

Return a list of all nwfilters currently known to the VMM. The elements in the returned list are instances of the Sys::Virt::NWFilter class.

my $nnames = $vmm->num_of_nwfilters()

Return the number of running nwfilters known to the VMM. This can be used as the maxids parameter to list_nwfilter_names.

my @filterNames = $vmm->list_nwfilter_names($maxnames)

Return a list of all nwfilter names currently known to the VMM. The names can be used with the get_nwfilter_by_name method.

my $dom = $vmm->get_domain_by_name($name)

Return the domain with a name of $name. The returned object is an instance of the Sys::Virt::Domain class.

my $dom = $vmm->get_domain_by_id($id)

Return the domain with a local id of $id. The returned object is an instance of the Sys::Virt::Domain class.

my $dom = $vmm->get_domain_by_uuid($uuid)

Return the domain with a globally unique id of $uuid. The returned object is an instance of the Sys::Virt::Domain class.

my $net = $vmm->get_network_by_name($name)

Return the network with a name of $name. The returned object is an instance of the Sys::Virt::Network class.

my $net = $vmm->get_network_by_uuid($uuid)

Return the network with a globally unique id of $uuid. The returned object is an instance of the Sys::Virt::Network class.

my $pool = $vmm->get_storage_pool_by_name($name)

Return the storage pool with a name of $name. The returned object is an instance of the Sys::Virt::StoragePool class.

my $pool = $vmm->get_storage_pool_by_uuid($uuid)

Return the storage pool with a globally unique id of $uuid. The returned object is an instance of the Sys::Virt::StoragePool class.

my $vol = $vmm->get_storage_volume_by_path($path)

Return the storage volume with a location of $path. The returned object is an instance of the Sys::Virt::StorageVol class.

my $vol = $vmm->get_storage_volume_by_key($key)

Return the storage volume with a globally unique id of $key. The returned object is an instance of the Sys::Virt::StorageVol class.

my $dev = $vmm->get_node_device_by_name($name)

Return the node device with a name of $name. The returned object is an instance of the Sys::Virt::NodeDevice class.

my $iface = $vmm->get_interface_by_name($name)

Return the interface with a name of $name. The returned object is an instance of the Sys::Virt::Interface class.

my $iface = $vmm->get_interface_by_mac($mac)

Return the interface with a MAC address of $mac. The returned object is an instance of the Sys::Virt::Interface class.

my $sec = $vmm->get_secret_by_uuid($uuid)

Return the secret with a globally unique id of $uuid. The returned object is an instance of the Sys::Virt::Secret class.

my $sec = $vmm->get_secret_by_usage($usageType, $usageID)

Return the secret with a usage type of $usageType, identified by $usageID. The returned object is an instance of the Sys::Virt::Secret class.

my $dom = $vmm->get_nwfilter_by_name($name)

Return the domain with a name of $name. The returned object is an instance of the Sys::Virt::NWFilter class.

my $dom = $vmm->get_nwfilter_by_uuid($uuid)

Return the nwfilter with a globally unique id of $uuid. The returned object is an instance of the Sys::Virt::NWFilter class.

my $xml = $vmm->find_storage_pool_sources($type, $srcspec[, $flags])

Probe for available storage pool sources for the pool of type $type. The $srcspec parameter can be undef, or a parameter to refine the discovery process, for example a server hostname for NFS discovery. The $flags parameter is optional, and if omitted defaults to zero. The returned scalar is an XML document describing the discovered storage pool sources.

$vmm->restore_domain($savefile)

Recreate a domain from the saved state file given in the $savefile parameter.

$vmm->get_max_vcpus($domtype)

Return the maximum number of vcpus that can be configured for a domain of type $domtype

my $hostname = $vmm->get_hostname()

Return the name of the host with which this connection is associated.

my $uri = $vmm->get_uri()

Return the URI associated with the open connection. This may be different from the URI used when initially connecting to libvirt, when 'auto-probing' or drivers occurrs.

my $xml = $vmm->get_sysinfo()

Return an XML documenting representing the host system information, typically obtained from SMBIOS tables.

my $type = $vmm->get_type()

Return the type of virtualization backend accessed by this VMM object. Currently the only supported type is Xen.

my $xml = $vmm->domain_xml_from_native($format, $config);

Convert the native hypervisor configuration $config which is in format <$format> into libvirrt domain XML. Valid values of $format vary between hypervisor drivers.

my $config = $vmm->domain_xml_to_native($format, $xml)

Convert the libvirt domain XML configuration $xml to a native hypervisor configuration in format $format

my $ver = $vmm->get_version()

Return the complete version number as a string encoded in the formula (major * 1000000) + (minor * 1000) + micro.

my $ver = $vmm->get_major_version

Return the major version number of the libvirt library.

my $ver = $vmm->get_minor_version

Return the minor version number of the libvirt library.

my $ver = $vmm->get_micro_version

Return the micro version number of the libvirt library.

my $ver = $vmm->get_library_version

Return the version number of the API associated with the active connection. This differs from get_version in that if the connection is to a remote libvirtd daemon, it will return the API version of the remote libvirt, rather than the local client.

$conn->is_secure()

Returns a true value if the current connection is secure against network interception. This implies either use of UNIX sockets, or encryption with a TCP stream.

$conn->is_encrypted()

Returns a true value if the current connection data stream is encrypted.

my $info = $con->get_node_info()

Returns a hash reference summarising the capabilities of the host node. The elements of the hash are as follows:

$conn->domain_event_register($callback)

Register a callback to received notificaitons of domain state change events. Only a single callback can be registered with each connection instance. The callback will be invoked with four parameters, an instance of Sys::Virt for the connection, an instance of Sys::Virt::Domain for the domain changing state, and a event and detail arguments, corresponding to the event constants defined in the Sys::Virt::Domain module. Before discarding the connection object, the callback must be deregistered, otherwise the connection object memory will never be released in garbage collection.

$conn->domain_event_deregister()

Unregister a callback, allowing the connection object to be garbage collected.

$callback = $conn->domain_event_register_any($dom, $eventID, $callback)

Register a callback to received notifications of domain events. The $dom parameter can be undef to request events on all known domains, or a specific Sys::Virt::Domain object to filter events. The $eventID parameter is one of the EVENT ID constants described later in this document. The $callback is a subroutine reference that will receive the events.

All callbacks receive a Sys::Virt connection as the first parameter and a Sys::Virt::Domain object indiciating the domain on which the event occurred as the second parameter. Subsequent parameters vary according to the event type

EVENT_ID_LIFECYCLE

Extra event and detail parameters defining the lifecycle transition that occurred.

EVENT_ID_REBOOT

No extra parameters

EVENT_ID_RTC_CHANGE

The utcoffset gives the offset from UTC in seconds

EVENT_ID_WATCHDOG

The action defines the action that is taken as a result of the watchdog triggering. One of the WATCHDOG constants described later

EVENT_ID_IO_ERROR

The srcPath is the file on the host which had the error. The devAlias is the unique device alias from the guest configuration associated with srcPath. The action is the action taken as a result of the error, one of the IO ERROR constants described later

EVENT_ID_GRAPHICS

The phase is the stage of the connection, one of the GRAPHICS PHASE constants described later. The local and remote parameters follow with the details of the local and remote network addresses. The authScheme describes how the user was authenticated (if at all). Finally identities is an array ref containing authenticated identities for the user, if any.

The return value is a unique callback ID that must be used when unregistering the event.

$conn->domain_event_deregister_any($callbackID)

Unregister a callback, associated with the $callbackID previously obtained from domain_event_register_any.

my $xml = $con->baseline_cpu(\@xml, $flags=0)

Given an array ref whose elements are XML documents describing host CPUs, compute the baseline CPU model that is operable across all hosts. The XML for the baseline CPU model is returned. The optional $flags parameter is currently unused and defaults to 0.

memory

The amount of physical memory in the host

model

The model of the CPU, eg x86_64

cpus

The total number of logical CPUs

mhz

The peak MHZ of the CPU

nodes

The number of NUMA cells

sockets

The number of CPU sockets

cores

The number of cores per socket

threads

The number of threads per core

my $info = $con->get_node_security_model()

Returns a hash reference summarising the security model of the host node. There are two keys in the hash, model specifying the name of the security model (eg 'selinux') and doi specifying the 'domain of interpretation' for security labels.

my $xml = $con->get_capabilities();

Returns an XML document describing the hypervisor capabilities

my $result = $con->compare_cpu($xml, $flags=0);

Checks whether the CPU definition in $xml is compatible with the current hypervisor connection. This can be used to determine whether it is safe to migrate a guest to this host. The returned result is one of the constants listed later

$mem = $con->get_node_free_memory();

Returns the current free memory on the host

@mem = $con->get_node_cells_free_memory($start, $end);

Returns the free memory on each NUMA cell between $start and $end.

The following sets of constants are useful when dealing with APIs in this package

When providing authentication callbacks, the following constants indicate the type of credential being requested

Sys::Virt::CRED_AUTHNAME

Identity to act as

Sys::Virt::CRED_USERNAME

Identity to authorize as

Sys::Virt::CRED_CNONCE

Client supplies a nonce

Sys::Virt::CRED_REALM

Authentication realm

Sys::Virt::CRED_ECHOPROMPT

Challenge response non-secret

Sys::Virt::CRED_NOECHOPROMPT

Challenge response secret

Sys::Virt::CRED_PASSPHRASE

Passphrase secret

Sys::Virt::CRED_LANGUAGE

RFC 1766 language code

Sys::Virt::CRED_EXTERNAL

Externally provided credential

Sys::Virt::CPU_COMPARE_INCOMPATIBLE

This host is missing one or more CPU features in the CPU description

Sys::Virt::CPU_COMPARE_IDENTICAL

The host has an identical CPU description

Sys::Virt::CPU_COMPARE_SUPERSET

The host offers a superset of the CPU descriptoon

Hopefully none, but the XS code needs to be audited to ensure it is not leaking memory.

Daniel P. Berrange <berrange@redhat.com>

Copyright (C) 2006-2009 Red Hat Copyright (C) 2006-2009 Daniel P. Berrange

This program is free software; you can redistribute it and/or modify it under the terms of either the GNU General Public License as published by the Free Software Foundation (either version 2 of the License, or at your option any later version), or, the Artistic License, as specified in the Perl README file.

Sys::Virt::Domain, Sys::Virt::Network, Sys::Virt::StoragePool, Sys::Virt::StorageVol, Sys::Virt::Error, http://libvirt.org