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Re: [Cluster-devel] [PATCH 1/3] New fencing script for Citrix XenServer and XCP.



Hi Fabio,

Looks like I had a few problems moving the code over to git. Your comments all sound perfectly valid. Do you want me to fix up and resubmit?

Cheers,
Matt.

> Date: Mon, 11 Apr 2011 07:01:29 +0200
> From: fdinitto redhat com
> To: cluster-devel redhat com; mgrac redhat com
> Subject: Re: [Cluster-devel] [PATCH 1/3] New fencing script for Citrix XenServer and XCP.
>
> Hi Matt,
>
> I'll leave the comments to the code to Marek, but we will need to do a
> few adjustments here and there to get this into the tree.
>
> XenAPI.py being a fence library needs to move into the libs/ section. It
> is not parsed/built/installed in this patch set.
>
> You sent us pre-built sources and that's not really ok. See for example
> the hardcoded path to the fence library and the addition of
> RELEASE_VERSION and BUILD_DATE at the end of the code for fence_xenapi.
> Those should be generated dynamically at build time to reflect the build
> info.
>
> Because I really like to make sure that COPYRIGHT and licences
> information are as exact and clear as possible, please also update
> docs/COPYRIGHT in the "exception" area. While the information in the
> file are absolutely fine, most people tend to look for a
> COPYRIGHT/LICENCE file rather than editing the file itself. It's fair
> that your contribution deserves the right credit and such.
>
> Cheers
> Fabio
>
> On 04/09/2011 06:54 AM, Matt Clark wrote:
> > Fencing script that uses the XenAPI to allow remote switch, status and list of virtual machines running on Citrix XenServer and Xen Cloud Platform hosts.
> > ---
> > fence/agents/xenapi/Makefile.am | 17 +++
> > fence/agents/xenapi/XenAPI.py | 209 ++++++++++++++++++++++++++++++++
> > fence/agents/xenapi/fence_xenapi.py | 227 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 453 insertions(+), 0 deletions(-)
> > create mode 100644 fence/agents/xenapi/Makefile.am
> > create mode 100755 fence/agents/xenapi/XenAPI.py
> > create mode 100644 fence/agents/xenapi/fence_xenapi.py
> >
> > diff --git a/fence/agents/xenapi/Makefile.am b/fence/agents/xenapi/Makefile.am
> > new file mode 100644
> > index 0000000..781975e
> > --- /dev/null
> > +++ b/fence/agents/xenapi/Makefile.am
> > @@ -0,0 +1,17 @@
> > +MAINTAINERCLEANFILES = Makefile.in
> > +
> > +TARGET = fence_xenapi
> > +
> > +SRC = "">> > +
> > +EXTRA_DIST = $(SRC)
> > +
> > +sbin_SCRIPTS = $(TARGET)
> > +
> > +man_MANS = $(TARGET).8
> > +
> > +include $(top_srcdir)/make/fencebuild.mk
> > +include $(top_srcdir)/make/fenceman.mk
> > +
> > +clean-local: clean-man
> > + rm -f $(TARGET)
> > diff --git a/fence/agents/xenapi/XenAPI.py b/fence/agents/xenapi/XenAPI.py
> > new file mode 100755
> > index 0000000..4f27ef5
> > --- /dev/null
> > +++ b/fence/agents/xenapi/XenAPI.py
> > @@ -0,0 +1,209 @@
> > +#============================================================================
> > +# This library is free software; you can redistribute it and/or
> > +# modify it under the terms of version 2.1 of the GNU Lesser General Public
> > +# License as published by the Free Software Foundation.
> > +#
> > +# This library is distributed in the hope that it will be useful,
> > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > +# Lesser General Public License for more details.
> > +#
> > +# You should have received a copy of the GNU Lesser General Public
> > +# License along with this library; if not, write to the Free Software
> > +# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> > +#============================================================================
> > +# Copyright (C) 2006 XenSource Inc.
> > +#============================================================================
> > +#
> > +# Parts of this file are based upon xmlrpclib.py, the XML-RPC client
> > +# interface included in the Python distribution.
> > +#
> > +# Copyright (c) 1999-2002 by Secret Labs AB
> > +# Copyright (c) 1999-2002 by Fredrik Lundh
> > +#
> > +# By obtaining, using, and/or copying this software and/or its
> > +# associated documentation, you agree that you have read, understood,
> > +# and will comply with the following terms and conditions:
> > +#
> > +# Permission to use, copy, modify, and distribute this software and
> > +# its associated documentation for any purpose and without fee is
> > +# hereby granted, provided that the above copyright notice appears in
> > +# all copies, and that both that copyright notice and this permission
> > +# notice appear in supporting documentation, and that the name of
> > +# Secret Labs AB or the author not be used in advertising or publicity
> > +# pertaining to distribution of the software without specific, written
> > +# prior permission.
> > +#
> > +# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
> > +# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
> > +# ABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
> > +# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
> > +# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
> > +# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
> > +# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
> > +# OF THIS SOFTWARE.
> > +# --------------------------------------------------------------------
> > +
> > +import gettext
> > +import xmlrpclib
> > +import httplib
> > +import socket
> > +
> > +translation = gettext.translation('xen-xm', fallback = True)
> > +
> > +class Failure(Exception):
> > + def __init__(self, details):
> > + try:
> > + # If this failure is MESSAGE_PARAMETER_COUNT_MISMATCH, then we
> > + # correct the return values here, to account for the fact that we
> > + # transparently add the session handle as the first argument.
> > + if details[0] == 'MESSAGE_PARAMETER_COUNT_MISMATCH':
> > + details[2] = str(int(details[2]) - 1)
> > + details[3] = str(int(details[3]) - 1)
> > +
> > + self.details = details
> > + except Exception, exn:
> > + self.details = ['INTERNAL_ERROR', 'Client-side: ' + str(exn)]
> > +
> > + def __str__(self):
> > + try:
> > + return translation.ugettext(self.details[0]) % self._details_map()
> > + except TypeError, exn:
> > + return "Message database broken: %s.\nXen-API failure: %s" % \
> > + (exn, str(self.details))
> > + except Exception, exn:
> > + import sys
> > + print >>sys.stderr, exn
> > + return "Xen-API failure: %s" % str(self.details)
> > +
> > + def _details_map(self):
> > + return dict([(str(i), self.details[i])
> > + for i in range(len(self.details))])
> > +
> > +
> > +_RECONNECT_AND_RETRY = (lambda _ : ())
> > +
> > +class UDSHTTPConnection(httplib.HTTPConnection):
> > + """ Stupid hacked up HTTPConnection subclass to allow HTTP over Unix domain
> > + sockets. """
> > + def connect(self):
> > + path = self.host.replace("_", "/")
> > + self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
> > + self.sock.connect(path)
> > +
> > +class UDSHTTP(httplib.HTTP):
> > + _connection_class = UDSHTTPConnection
> > +
> > +class UDSTransport(xmlrpclib.Transport):
> > + def make_connection(self, host):
> > + return UDSHTTP(host)
> > +
> > +class Session(xmlrpclib.ServerProxy):
> > + """A server proxy and session manager for communicating with Xend using
> > + the Xen-API.
> > +
> > + Example:
> > +
> > + session = Session('http://localhost:9363/')
> > + session.login_with_password('me', 'mypassword')
> > + session.xenapi.VM.start(vm_uuid)
> > + session.xenapi.session.logout()
> > +
> > + For now, this class also supports the legacy XML-RPC API, using
> > + session.xend.domain('Domain-0') and similar. This support will disappear
> > + once there is a working Xen-API replacement for every call in the legacy
> > + API.
> > + """
> > +
> > + def __init__(self, uri, transport=None, encoding=None, verbose=0,
> > + allow_none=1):
> > + xmlrpclib.ServerProxy.__init__(self, uri, transport, encoding,
> > + verbose, allow_none)
> > + self._session = None
> > + self.last_login_method = None
> > + self.last_login_params = None
> > +
> > +
> > + def xenapi_request(self, methodname, params):
> > + if methodname.startswith('login'):
> > + self._login(methodname, params)
> > + return None
> > + else:
> > + retry_count = 0
> > + while retry_count < 3:
> > + full_params = (self._session,) + params
> > + result = _parse_result(getattr(self, methodname)(*full_params))
> > + if result == _RECONNECT_AND_RETRY:
> > + retry_count += 1
> > + if self.last_login_method:
> > + self._login(self.last_login_method,
> > + self.last_login_params)
> > + else:
> > + raise xmlrpclib.Fault(401, 'You must log in')
> > + else:
> > + return result
> > + raise xmlrpclib.Fault(
> > + 500, 'Tried 3 times to get a valid session, but failed')
> > +
> > +
> > + def _login(self, method, params):
> > + result = _parse_result(getattr(self, 'session.%s' % method)(*params))
> > + if result == _RECONNECT_AND_RETRY:
> > + raise xmlrpclib.Fault(
> > + 500, 'Received SESSION_INVALID when logging in')
> > + self._session = result
> > + self.last_login_method = method
> > + self.last_login_params = params
> > +
> > +
> > + def __getattr__(self, name):
> > + if name == 'xenapi':
> > + return _Dispatcher(self.xenapi_request, None)
> > + elif name.startswith('login'):
> > + return lambda *params: self._login(name, params)
> > + else:
> > + return xmlrpclib.ServerProxy.__getattr__(self, name)
> > +
> > +def xapi_local():
> > + return Session("http://_var_xapi_xapi/", transport=UDSTransport())
> > +
> > +def _parse_result(result):
> > + if type(result) != dict or 'Status' not in result:
> > + raise xmlrpclib.Fault(500, 'Missing Status in response from server' + result)
> > + if result['Status'] == 'Success':
> > + if 'Value' in result:
> > + return result['Value']
> > + else:
> > + raise xmlrpclib.Fault(500,
> > + 'Missing Value in response from server')
> > + else:
> > + if 'ErrorDescription' in result:
> > + if result['ErrorDescription'][0] == 'SESSION_INVALID':
> > + return _RECONNECT_AND_RETRY
> > + else:
> > + raise Failure(result['ErrorDescription'])
> > + else:
> > + raise xmlrpclib.Fault(
> > + 500, 'Missing ErrorDescription in response from server')
> > +
> > +
> > +# Based upon _Method from xmlrpclib.
> > +class _Dispatcher:
> > + def __init__(self, send, name):
> > + self.__send = send
> > + self.__name = name
> > +
> > + def __repr__(self):
> > + if self.__name:
> > + return '<XenAPI._Dispatcher for %s>' % self.__name
> > + else:
> > + return '<XenAPI._Dispatcher>'
> > +
> > + def __getattr__(self, name):
> > + if self.__name is None:
> > + return _Dispatcher(self.__send, name)
> > + else:
> > + return _Dispatcher(self.__send, "%s.%s" % (self.__name, name))
> > +
> > + def __call__(self, *args):
> > + return self.__send(self.__name, args)
> > diff --git a/fence/agents/xenapi/fence_xenapi.py b/fence/agents/xenapi/fence_xenapi.py
> > new file mode 100644
> > index 0000000..0657f4e
> > --- /dev/null
> > +++ b/fence/agents/xenapi/fence_xenapi.py
> > @@ -0,0 +1,227 @@
> > +#!/usr/bin/python
> > +#
> > +#############################################################################
> > +# Copyright 2011 Matt Clark
> > +# This file is part of fence-xenserver
> > +#
> > +# fence-xenserver is free software: you can redistribute it and/or modify
> > +# it under the terms of 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.
> > +#
> > +# fence-xenserver is distributed in the hope that it will be useful,
> > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > +# GNU General Public License for more details.
> > +#
> > +# You should have received a copy of the GNU General Public License
> > +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> > +
> > +# Please let me know if you are using this script so that I can work out
> > +# whether I should continue support for it. mattjclark0407 at hotmail dot com
> > +#############################################################################
> > +
> > +#############################################################################
> > +# It's only just begun...
> > +# Current status: completely usable. This script is now working well and,
> > +# has a lot of functionality as a result of the fencing.py library and the
> > +# XenAPI libary.
> > +
> > +#############################################################################
> > +# Please let me know if you are using this script so that I can work out
> > +# whether I should continue support for it. mattjclark0407 at hotmail dot com
> > +
> > +import sys
> > +sys.path.append("/usr/lib/fence")
> > +from fencing import *
> > +import XenAPI
> > +
> > +EC_BAD_SESSION = 1
> > +# Find the status of the port given in the -U flag of options.
> > +def get_power_fn(session, options):
> > + if options.has_key("-v"):
> > + verbose = True
> > + else:
> > + verbose = False
> > +
> > + try:
> > + # Get a reference to the vm specified in the UUID or vm_name/port parameter
> > + vm = return_vm_reference(session, options)
> > + # Query the VM for its' associated parameters
> > + record = session.xenapi.VM.get_record(vm);
> > + # Check that we are not trying to manipulate a template or a control
> > + # domain as they show up as VM's with specific properties.
> > + if not(record["is_a_template"]) and not(record["is_control_domain"]):
> > + status = record["power_state"]
> > + if verbose: print "UUID:", record["uuid"], "NAME:", record["name_label"], "POWER STATUS:", record["power_state"]
> > + # Note that the VM can be in the following states (from the XenAPI document)
> > + # Halted: VM is offline and not using any resources.
> > + # Paused: All resources have been allocated but the VM itself is paused and its vCPUs are not running
> > + # Running: Running
> > + # Paused: VM state has been saved to disk and it is nolonger running. Note that disks remain in-Use while
> > + # We want to make sure that we only return the status "off" if the machine is actually halted as the status
> > + # is checked before a fencing action. Only when the machine is Halted is it not consuming resources which
> > + # may include whatever you are trying to protect with this fencing action.
> > + return (status=="Halted" and "off" or "on")
> > + except Exception, exn:
> > + print str(exn)
> > +
> > + return "Error"
> > +
> > +# Set the state of the port given in the -U flag of options.
> > +def set_power_fn(session, options):
> > + action = "">> > + if options.has_key("-v"):
> > + verbose = True
> > + else:
> > + verbose = False
> > +
> > + try:
> > + # Get a reference to the vm specified in the UUID or vm_name/port parameter
> > + vm = return_vm_reference(session, options)
> > + # Query the VM for its' associated parameters
> > + record = session.xenapi.VM.get_record(vm)
> > + # Check that we are not trying to manipulate a template or a control
> > + # domain as they show up as VM's with specific properties.
> > + if not(record["is_a_template"]) and not(record["is_control_domain"]):
> > + if( action == "on" ):
> > + # Start the VM
> > + session.xenapi.VM.start(vm, False, True)
> > + elif( action == "off" ):
> > + # Force shutdown the VM
> > + session.xenapi.VM.hard_shutdown(vm)
> > + elif( action == "reboot" ):
> > + # Force reboot the VM
> > + session.xenapi.VM.hard_reboot(vm)
> > + except Exception, exn:
> > + print str(exn);
> > +
> > +# Function to populate an array of virtual machines and their status
> > +def get_outlet_list(session, options):
> > + result = {}
> > + if options.has_key("-v"):
> > + verbose = True
> > + else:
> > + verbose = False
> > +
> > + try:
> > + # Return an array of all the VM's on the host
> > + vms = session.xenapi.VM.get_all()
> > + for vm in vms:
> > + # Query the VM for its' associated parameters
> > + record = session.xenapi.VM.get_record(vm);
> > + # Check that we are not trying to manipulate a template or a control
> > + # domain as they show up as VM's with specific properties.
> > + if not(record["is_a_template"]) and not(record["is_control_domain"]):
> > + name = record["name_label"]
> > + uuid = record["uuid"]
> > + status = record["power_state"]
> > + result[uuid] = (name, status)
> > + if verbose: print "UUID:", record["uuid"], "NAME:", name, "POWER STATUS:", record["power_state"]
> > + except Exception, exn:
> > + print str(exn);
> > +
> > + return result
> > +
> > +# Function to initiate the XenServer session via the XenAPI library.
> > +def connect_and_login(options):
> > + url = "">> > + username = options["-l"]
> > + password = options["-p"]
> > +
> > + try:
> > + # Create the XML RPC session to the specified URL.
> > + session = XenAPI.Session(url);
> > + # Login using the supplied credentials.
> > + session.xenapi.login_with_password(username, password);
> > + except Exception, exn:
> > + print str(exn);
> > + # http://sources.redhat.com/cluster/wiki/FenceAgentAPI says that for no connectivity
> > + # the exit value should be 1. It doesn't say anything about failed logins, so
> > + # until I hear otherwise it is best to keep this exit the same to make sure that
> > + # anything calling this script (that uses the same information in the web page
> > + # above) knows that this is an error condition, not a msg signifying a down port.
> > + sys.exit(EC_BAD_SESSION);
> > + return session;
> > +
> > +# return a reference to the VM by either using the UUID or the vm_name/port. If the UUID is set then
> > +# this is tried first as this is the only properly unique identifier.
> > +# Exceptions are not handled in this function, code that calls this must be ready to handle them.
> > +def return_vm_reference(session, options):
> > + if options.has_key("-v"):
> > + verbose = True
> > + else:
> > + verbose = False
> > +
> > + # Case where the UUID has been specified
> > + if options.has_key("-U"):
> > + uuid = options["-U"].lower()
> > + # When using the -n parameter for name, we get an error message (in verbose
> > + # mode) that tells us that we didn't find a VM. To immitate that here we
> > + # need to catch and re-raise the exception produced by get_by_uuid.
> > + try:
> > + return session.xenapi.VM.get_by_uuid(uuid)
> > + except Exception,exn:
> > + if verbose: print "No VM's found with a UUID of \"%s\"" %uuid
> > + raise
> > +
> > +
> > + # Case where the vm_name/port has been specified
> > + if options.has_key("-n"):
> > + vm_name = options["-n"]
> > + vm_arr = session.xenapi.VM.get_by_name_label(vm_name)
> > + # Need to make sure that we only have one result as the vm_name may
> > + # not be unique. Average case, so do it first.
> > + if len(vm_arr) == 1:
> > + return vm_arr[0]
> > + else:
> > + if len(vm_arr) == 0:
> > + if verbose: print "No VM's found with a name of \"%s\"" %vm_name
> > + # NAME_INVALID used as the XenAPI throws a UUID_INVALID if it can't find
> > + # a VM with the specified UUID. This should make the output look fairly
> > + # consistent.
> > + raise Exception("NAME_INVALID")
> > + else:
> > + if verbose: print "Multiple VM's have the name \"%s\", use UUID instead" %vm_name
> > + raise Exception("MULTIPLE_VMS_FOUND")
> > +
> > + # We should never get to this case as the input processing checks that either the UUID or
> > + # the name parameter is set. Regardless of whether or not a VM is found the above if
> > + # statements will return to the calling function (either by exception or by a reference
> > + # to the VM).
> > + raise Exception("VM_LOGIC_ERROR")
> > +
> > +def main():
> > +
> > + device_opt = [ "help", "version", "agent", "quiet", "verbose", "debug", "action",
> > + "login", "passwd", "passwd_script", "port", "test", "separator",
> > + "no_login", "no_password", "power_timeout", "shell_timeout",
> > + "login_timeout", "power_wait", "session_url", "uuid" ]
> > +
> > + atexit.register(atexit_handler)
> > +
> > + options=process_input(device_opt)
> > +
> > + options = check_input(device_opt, options)
> > +
> > + docs = { }
> > + docs["shortdesc"] = "XenAPI based fencing for the Citrix XenServer virtual machines."
> > + docs["longdesc"] = "\
> > +fence_cxs is an I/O Fencing agent used on Citrix XenServer hosts. \
> > +It uses the XenAPI, supplied by Citrix, to establish an XML-RPC sesssion \
> > +to a XenServer host. Once the session is established, further XML-RPC \
> > +commands are issued in order to switch on, switch off, restart and query \
> > +the status of virtual machines running on the host."
> > + show_docs(options, docs)
> > +
> > + xenSession = connect_and_login(options)
> > +
> > + # Operate the fencing device
> > + result = fence_action(xenSession, options, set_power_fn, get_power_fn, get_outlet_list)
> > +
> > + sys.exit(result)
> > +
> > +if __name__ == "__main__":
> > + main()
> > +RELEASE_VERSION="3.1.2.11-2b5b-dirty"
> > +BUILD_DATE="(built Fri Mar 25 22:57:28 EST 2011)"
>

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