libvirtError that can be subclassed to add additional functionality when raising a libvirt exception. A partial definition of the libvirtError class definition looks like:
Example 8.1. Libvirt module libvirtError class definition
class libvirtError(exceptions.Exception) def __init__(self, defmsg, conn=None, dom=None, net=None, pool=None, vol=None): # Never call virGetLastError(). # virGetLastError() is now thread local err = virGetLastError() if err is None: msg = defmsg else: msg = err[2] Exception.__init__(self, msg) self.err = err def get_error_code(self): if self.err is None: return None return self.err[0] def get_error_domain(self): if self.err is None: return None return self.err[1] def get_error_message(self): if self.err is None: return None return self.err[2] def get_error_level(self): if self.err is None: return None return self.err[3] def get_str1(self): if self.err is None: return None return self.err[4] def get_str2(self): if self.err is None: return None return self.err[5] def get_str3(self): if self.err is None: return None return self.err[6] def get_int1(self): if self.err is None: return None return self.err[7] def get_int2(self): if self.err is None: return None return self.err[8]
raise statement. Actually this is not of much use unless you subclass the libvirtError class with your own class which would contain the needed behaviour. You should also make note of the methods which can obtain the error information. A description of these methods follows:
get_error_code returns the error code that was returned from the error. This is one of the data definition from the Python libvirt module. Some of the higher numbered entries from this list my not be available in your Python libvirt module.
VIR_ERR_OK = 0 VIR_ERR_INTERNAL_ERROR = 1 # internal error VIR_ERR_NO_MEMORY = 2 # memory allocation failure VIR_ERR_NO_SUPPORT = 3 # no support for this function VIR_ERR_UNKNOWN_HOST = 4 # could not resolve hostname VIR_ERR_NO_CONNECT = 5 # can not connect to hypervisor VIR_ERR_INVALID_CONN = 6 # invalid connection object VIR_ERR_INVALID_DOMAIN = 7 # invalid domain object VIR_ERR_INVALID_ARG = 8 # invalid function argument VIR_ERR_OPERATION_FAILED = 9 # a command to hypervisor failed VIR_ERR_GET_FAILED = 10 # a HTTP GET command to failed VIR_ERR_POST_FAILED = 11 # a HTTP POST command to failed VIR_ERR_HTTP_ERROR = 12 # unexpected HTTP error code VIR_ERR_SEXPR_SERIAL = 13 # failure to serialize an S-Expr VIR_ERR_NO_XEN = 14 # could not open Xen hypervisor control VIR_ERR_XEN_CALL = 15 # failure doing an hypervisor call VIR_ERR_OS_TYPE = 16 # unknown OS type VIR_ERR_NO_KERNEL = 17 # missing kernel information VIR_ERR_NO_ROOT = 18 # missing root device information VIR_ERR_NO_SOURCE = 19 # missing source device information VIR_ERR_NO_TARGET = 20 # missing target device information VIR_ERR_NO_NAME = 21 # missing domain name information VIR_ERR_NO_OS = 22 # missing domain OS information VIR_ERR_NO_DEVICE = 23 # missing domain devices information VIR_ERR_NO_XENSTORE = 24 # could not open Xen Store control VIR_ERR_DRIVER_FULL = 25 # too many drivers registered VIR_ERR_CALL_FAILED = 26 # not supported by the drivers (DEPRECATED) VIR_ERR_XML_ERROR = 27 # an XML description is not well formed or broken VIR_ERR_DOM_EXIST = 28 # the domain already exist VIR_ERR_OPERATION_DENIED = 29 # operation forbidden on read-only connections VIR_ERR_OPEN_FAILED = 30 # failed to open a conf file VIR_ERR_READ_FAILED = 31 # failed to read a conf file VIR_ERR_PARSE_FAILED = 32 # failed to parse a conf file VIR_ERR_CONF_SYNTAX = 33 # failed to parse the syntax of a conf file VIR_ERR_WRITE_FAILED = 34 # failed to write a conf file VIR_ERR_XML_DETAIL = 35 # detail of an XML error VIR_ERR_INVALID_NETWORK = 36 # invalid network object VIR_ERR_NETWORK_EXIST = 37 # the network already exist VIR_ERR_SYSTEM_ERROR = 38 # general system call failure VIR_ERR_RPC = 39 # some sort of RPC error VIR_ERR_GNUTLS_ERROR = 40 # error from a GNUTLS call VIR_WAR_NO_NETWORK = 41 # failed to start network VIR_ERR_NO_DOMAIN = 42 # domain not found or unexpectedly disappeared VIR_ERR_NO_NETWORK = 43 # network not found VIR_ERR_INVALID_MAC = 44 # invalid MAC address VIR_ERR_AUTH_FAILED = 45 # authentication failed VIR_ERR_INVALID_STORAGE_POOL = 46 # invalid storage pool object VIR_ERR_INVALID_STORAGE_VOL = 47 # invalid storage vol object VIR_WAR_NO_STORAGE = 48 # failed to start storage VIR_ERR_NO_STORAGE_POOL = 49 # storage pool not found VIR_ERR_NO_STORAGE_VOL = 50 # storage vol not found VIR_WAR_NO_NODE = 51 # failed to start node driver VIR_ERR_INVALID_NODE_DEVICE = 52 # invalid node device object VIR_ERR_NO_NODE_DEVICE = 53 # node device not found VIR_ERR_NO_SECURITY_MODEL = 54 # security model not found VIR_ERR_OPERATION_INVALID = 55 # operation is not applicable at this time VIR_WAR_NO_INTERFACE = 56 # failed to start interface driver VIR_ERR_NO_INTERFACE = 57 # interface driver not running VIR_ERR_INVALID_INTERFACE = 58 # invalid interface object VIR_ERR_MULTIPLE_INTERFACES = 59 # more than one matching interface found VIR_WAR_NO_NWFILTER = 60 # failed to start nwfilter driver VIR_ERR_INVALID_NWFILTER = 61 # invalid nwfilter object VIR_ERR_NO_NWFILTER = 62 # nw filter pool not found VIR_ERR_BUILD_FIREWALL = 63 # nw filter pool not found VIR_WAR_NO_SECRET = 64 # failed to start secret storage VIR_ERR_INVALID_SECRET = 65 # invalid secret VIR_ERR_NO_SECRET = 66 # secret not found VIR_ERR_CONFIG_UNSUPPORTED = 67 # unsupported configuration construct VIR_ERR_OPERATION_TIMEOUT = 68 # timeout occurred during operation VIR_ERR_MIGRATE_PERSIST_FAILED = 69 # a migration worked, but making the VM persist on the dest host failed VIR_ERR_HOOK_SCRIPT_FAILED = 70 # a synchronous hook script failed VIR_ERR_INVALID_DOMAIN_SNAPSHOT = 71 # invalid domain snapshot VIR_ERR_NO_DOMAIN_SNAPSHOT = 72 # domain snapshot was not found VIR_ERR_INVALID_STREAM = 73 # invalid i/o stream VIR_ERR_ARGUMENT_UNSUPPORTED = 74 # an argument was unsupported VIR_ERR_STORAGE_PROBE_FAILED = 75 # a storage probe failed VIR_ERR_STORAGE_POOL_BUILT = 76 VIR_ERR_SNAPSHOT_REVERT_RISKY = 77 VIR_ERR_OPERATION_ABORTED = 78 # the operation was aborted VIR_ERR_AUTH_CANCELLED = 79 VIR_ERR_NO_DOMAIN_METADATA = 80 # no domain metadata was found VIR_ERR_MIGRATE_UNSAFE = 81 VIR_ERR_OVERFLOW = 82 # an overflow situation was detected VIR_ERR_BLOCK_COPY_ACTIVE = 83 VIR_ERR_OPERATION_UNSUPPORTED = 84 # the operation was unsupported VIR_ERR_SSH = 85 # an ssh error was detected VIR_ERR_AGENT_UNRESPONSIVE = 86 # an agent timeout was detected VIR_ERR_RESOURCE_BUSY = 87 VIR_ERR_ACCESS_DENIED = 88 VIR_ERR_DBUS_SERVICE = 89 VIR_ERR_STORAGE_VOL_EXIST = 90 VIR_ERR_CPU_INCOMPATIBLE = 91 VIR_ERR_XML_INVALID_SCHEMA = 92
get_error_domain is named that for legacy reasons, but really represents which part of libvirt generated the error. This is one of the data definition from the Python libvirt module. Some of the higher numbered entries from this list my not be available in your Python libvirt module. The full list is:
VIR_FROM_NONE = 0 VIR_FROM_XEN = 1 # Error at Xen hypervisor layer VIR_FROM_XEND = 2 # Error at connection with xend daemon VIR_FROM_XENSTORE = 3 # Error at connection with xen store VIR_FROM_SEXPR = 4 # Error in the S-Expression code VIR_FROM_XML = 5 # Error in the XML code VIR_FROM_DOM = 6 # Error when operating on a domain VIR_FROM_RPC = 7 # Error in the XML-RPC code VIR_FROM_PROXY = 8 # Error in the proxy code VIR_FROM_CONF = 9 # Error in the configuration file handling VIR_FROM_QEMU = 10 # Error at the QEMU daemon VIR_FROM_NET = 11 # Error when operating on a network VIR_FROM_TEST = 12 # Error from test driver VIR_FROM_REMOTE = 13 # Error from remote driver VIR_FROM_OPENVZ = 14 # Error from OpenVZ driver VIR_FROM_XENXM = 15 # Error at Xen XM layer VIR_FROM_STATS_LINUX = 16 # Error in the Linux Stats code VIR_FROM_LXC = 17 # Error from Linux Container driver VIR_FROM_STORAGE = 18 # Error from storage driver VIR_FROM_NETWORK = 19 # Error from network config VIR_FROM_DOMAIN = 20 # Error from domain config VIR_FROM_UML = 21 # Error at the UML driver VIR_FROM_NODEDEV = 22 # Error from node device monitor VIR_FROM_XEN_INOTIFY = 23 # Error from xen inotify layer VIR_FROM_SECURITY = 24 # Error from security framework VIR_FROM_VBOX = 25 # Error from VirtualBox driver VIR_FROM_INTERFACE = 26 # Error when operating on an interface VIR_FROM_ONE = 27 # Error from OpenNebula driver VIR_FROM_ESX = 28 # Error from ESX driver VIR_FROM_PHYP = 29 # Error from IBM power hypervisor VIR_FROM_SECRET = 30 # Error from secret storage VIR_FROM_CPU = 31 # Error from CPU driver VIR_FROM_XENAPI = 32 # Error from XenAPI VIR_FROM_NWFILTER = 33 # Error from network filter driver VIR_FROM_HOOK = 34 # Error from Synchronous hooks VIR_FROM_DOMAIN_SNAPSHOT = 35 # Error from domain snapshot VIR_FROM_AUDIT = 36 VIR_FROM_SYSINFO = 37 VIR_FROM_STREAMS = 38 VIR_FROM_VMWARE = 39 VIR_FROM_EVENT = 40 VIR_FROM_LIBXL = 41 VIR_FROM_LOCKING = 42 VIR_FROM_HYPERV = 43 VIR_FROM_CAPABILITIES = 44 VIR_FROM_URI = 45 VIR_FROM_AUTH = 46 VIR_FROM_DBUS = 47 VIR_FROM_PARALLELS = 48 VIR_FROM_DEVICE = 49 VIR_FROM_SSH = 50 VIR_FROM_LOCKSPACE = 51 VIR_FROM_INITCTL = 52 VIR_FROM_IDENTITY = 53 VIR_FROM_CGROUP = 54 VIR_FROM_ACCESS = 55 VIR_FROM_SYSTEMD = 56 VIR_FROM_BHYVE = 57 VIR_FROM_CRYPTO = 58 VIR_FROM_FIREWALL = 59 VIR_FROM_POLKIT = 60
get_error_message is a human-readable string describing the error.
get_error_level describes the severity of the error. This is one of the data definition from the Python libvirt module. The full list of levels is:
VIR_ERR_NONE = 0 VIR_ERR_WARNING = 1 # A simple warning VIR_ERR_ERROR = 2 # An error
get_error_str1 gives extra human readable information.
get_error_str2 gives extra human readable information.
get_error_str3 gives extra human readable information.
get_error_int1 gives extra numeric information that may be useful for further classifying the error.
get_error_int2 gives extra numeric information that may be useful for further classifying the error.
virGetLastError function can be used to obtain a Python list that contains all the information from the error reported from libvirt. This information is kept in thread local storage so separate threads can safely use this function concurrently. Note that it does not make a copy, so error information can be lost if the current thread calls this function subsequently. The following code demonstrates the use of virGetLastError:
Example 8.2. Using virGetLastError
# Example-24.py #!/usr/bin/env python3 import sys import libvirt def report_libvirt_error(): """Call virGetLastError function to get the last error information.""" err = libvirt.virGetLastError() print('Error code: '+str(err[0]), file=sys.stderr) print('Error domain: '+str(err[1]), file=sys.stderr) print('Error message: '+err[2], file=sys.stderr) print('Error level: '+str(err[3]), file=sys.stderr) if err[4] != None: print('Error string1: '+err[4], file=sys.stderr) else: print('Error string1:', file=sys.stderr) if err[5] != None: print('Error string2: '+err[5], file=sys.stderr) else: print('Error string2:', file=sys.stderr) if err[6] != None: print('Error string3: '+err[6], file=sys.stderr) else: print('Error string3:', file=sys.stderr) print('Error int1: '+str(err[7]), file=sys.stderr) print('Error int2: '+str(err[8]), file=sys.stderr) exit(1) try: conn = libvirt.open('qemu:///system') # invalidate the parameter to force an error except: report_libvirt_error() conn.close() exit(0)