Open Stack

For what it is worth...I was able to code a weigher. By dropping the code
below into a .py file in the weights directory and restarting the
scheduler, the scheduler will automatically consider if instances in the
same group are on a node before placing another instance there. For what it
is worth, both the ram weigher and the antiAffinity weigher are on the
playing field and so I have set "one node in the same group= 100GB of ram".

Thanks,
Danny Beutler

"""
AntiAffinityWeigher.  Weigh hosts by whether or not they have another host
in the same group.

"""

from oslo.config import cfg

from nova import db
from nova.openstack.common.gettextutils import _
from nova.scheduler import weights
from nova.scheduler import filters
from nova.openstack.common import log as logging

LOG = logging.getLogger(__name__)

anti_affinity_weight_opts = [
        cfg.FloatOpt('antiAffinityWeigher_Multiplier',
                     default=1.0,
                     help='Multiplier used for weighing hosts.  Negative '
                          'numbers mean to spread vs stack.'),
]

CONF = cfg.CONF
CONF.register_opts(anti_affinity_weight_opts)


class AntiAffinityWeigher(weights.BaseHostWeigher):
    def _weight_multiplier(self):
        """Override the weight multiplier."""
        return CONF.antiAffinityWeigher_Multiplier

    def _weigh_object(self, host_state, weight_properties):
        group_hosts = weight_properties.get('group_hosts') or []
        LOG.debug(_("Group anti affinity weigher: check if %(host)s not "
                    "in %(configured)s"), {'host': host_state.host,
                                           'configured': group_hosts})
        if group_hosts:
            group_hosts = weight_properties.get('group_hosts') or []
            num_instances_in_group = group_hosts.count(host_state.host)
            LOG.debug(_("Number of instances in the same group on this node
%(host)s"), {'host': num_instances_in_group})
            return group_hosts.count(host_state.host) * -100000

        # No groups configured
        return 0




On Mon, Aug 4, 2014 at 12:14 PM, Dugger, Donald D <donald.d.dugger at intel.com
> wrote:

>  Danny-
>
>
>
> People have been thinking about affinity/anti-affinity scheduling so this
> is a good area to look at but we might want to think of a general approach
> that addresses this and other issues.  I know that Yathi & Debo have
> proposed a BP:
>
>
>
>
> https://blueprints.launchpad.net/nova/+spec/solver-scheduler
>
>
>
> you might want to check it out and see how it relates to your issues.
>
>
>
> --
>
> Don Dugger
>
> "Censeo Toto nos in Kansa esse decisse." - D. Gale
>
> Ph: 303/443-3786
>
>
>
> *From:* Danny Beutler [mailto:dannybeutler at gmail.com]
> *Sent:* Friday, August 1, 2014 10:47 AM
> *To:* openstack at lists.openstack.org
> *Subject:* [Openstack] Custom Nova Scheduler Weigher
>
>
>
> I am in the process of implementing a custom weigher class. I have created
> a weigher that prefers hosts which do not have other instances in the same
> group (think GroupAntiAffinityFilter but for weight).
>
> Here is the code for the class:
>
> # Copyright (c) 2011 OpenStack Foundation
> # All Rights Reserved.
> #
> #    Licensed under the Apache License, Version 2.0 (the "License"); you
> may
> #    not use this file except in compliance with the License. You may
> obtain
> #    a copy of the License at
> #
> #         http://www.apache.org/licenses/LICENSE-2.0
> #
> #    Unless required by applicable law or agreed to in writing, software
> #    distributed under the License is distributed on an "AS IS" BASIS,
> WITHOUT
> #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
> the
> #    License for the specific language governing permissions and
> limitations
>
> """
> AntiAffinityWeigher.  Weigh hosts by whether or not they have another host
> in the same group.
>
> """
>
> from oslo.config import cfg
>
> from nova import db
> from nova.openstack.common.gettextutils import _
> from nova.scheduler import weights
> from nova.scheduler import filters
> from nova.openstack.common import log as logging
>
> LOG = logging.getLogger(__name__)
>
> anti_affinity_weight_opts = [
>         cfg.FloatOpt('antiAffinityWeigher_Multiplier',
>                      default=1000.0,
>                      help='Multiplier used for weighing hosts.  Negative '
>                           'numbers mean to stack vs spread.'),
> ]
>
> CONF = cfg.CONF
> CONF.register_opts(anti_affinity_weight_opts)
>
>
> class AntiAffinityWeigher(weights.BaseHostWeigher):
>     def _weight_multiplier(self):
>         """Override the weight multiplier."""
>         return CONF.antiAffinityWeigher_Multiplier
>
>     def _weigh_object(self, host_state, weight_properties):
>         group_hosts = weight_properties.get('group_hosts') or []
>         LOG.debug(_("Group anti affinity Weigher: check if %(host)s not "
>             "in %(configured)s"), {'host': host_state.host,
>             'configured': group_hosts})
>         if group_hosts:
>             return group_hosts.amount() * 100000
>
>         # No groups configured
>         return 0
>
>   I know the python is at least close to correct because the scheduler
> service wouldn't even restart until it was. After I got the bugs worked out
> of the module, I added modified the /etc/nova/nova.conf file to have the
> custom weigher like so:
>
> scheduler_weight_classes=nova.scheduler.weights.all_weighers,nova.scheduler.AntiAffinityWeigher
>
> After restarting the scheduler service I get the following error in the
> nova logs:
> <178>Aug  1 16:46:11 node-25 nova-nova CRITICAL: Class AntiAffinityWeigher
> cannot be found (['Traceback (most recent call last):\n', '  File
> "/usr/lib/python2.6/site-packages/nova/openstack/common/importutils.py",
> line 31, in import_class\n    return getattr(sys.modules[mod_str],
> class_str)\n', "AttributeError: 'module' object has no attribute
> 'AntiAffinityWeigher'\n"])
> Traceback (most recent call last):
>   File "/usr/bin/nova-scheduler", line 10, in <module>
>     sys.exit(main())
>   File "/usr/lib/python2.6/site-packages/nova/cmd/scheduler.py", line 39,
> in main
>     topic=CONF.scheduler_topic)
>   File "/usr/lib/python2.6/site-packages/nova/service.py", line 257, in
> create
>     db_allowed=db_allowed)
>   File "/usr/lib/python2.6/site-packages/nova/service.py", line 139, in
> __init__
>     self.manager = manager_class(host=self.host, *args, **kwargs)
>   File "/usr/lib/python2.6/site-packages/nova/scheduler/manager.py", line
> 65, in __init__
>     self.driver = importutils.import_object(scheduler_driver)
>   File
> "/usr/lib/python2.6/site-packages/nova/openstack/common/importutils.py",
> line 40, in import_object
>     return import_class(import_str)(*args, **kwargs)
>   File
> "/usr/lib/python2.6/site-packages/nova/scheduler/filter_scheduler.py", line
> 59, in __init__
>     super(FilterScheduler, self).__init__(*args, **kwargs)
>   File "/usr/lib/python2.6/site-packages/nova/scheduler/driver.py", line
> 103, in __init__
>     CONF.scheduler_host_manager)
>   File
> "/usr/lib/python2.6/site-packages/nova/openstack/common/importutils.py",
> line 40, in import_object
>     return import_class(import_str)(*args, **kwargs)
>   File "/usr/lib/python2.6/site-packages/nova/scheduler/host_manager.py",
> line 297, in __init__
>     CONF.scheduler_weight_classes)
>   File "/usr/lib/python2.6/site-packages/nova/loadables.py", line 105, in
> get_matching_classes
>     obj = importutils.import_class(cls_name)
>   File
> "/usr/lib/python2.6/site-packages/nova/openstack/common/importutils.py",
> line 35, in import_class
>     traceback.format_exception(*sys.exc_info())))
> ImportError: Class AntiAffinityWeigher cannot be found (['Traceback (most
> recent call last):\n', '  File
> "/usr/lib/python2.6/site-packages/nova/openstack/common/importutils.py",
> line 31, in import_class\n    return getattr(sys.modules[mod_str],
> class_str)\n', "AttributeError: 'module' object has no attribute
> 'AntiAffinityWeigher'\n"])
>
>
>   I have also tried a few different naming conventions such as
> "AntiAffinityWeigher.AntiAffinityWeigher" and
> "myWeigher.AntiAffinityWeigher" to no avail.
>
> Any help would be greatly appreciated.
>
> Thanks,
> Danny
>
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