grizzly: add scheduler hint for VM groups

[Tom Fifield]

https://review.openstack.org/#/c/21070/ introduced a new feature in nova: Support for scheduler hints for VM groups

A new scheduler filter is added:
   94 * |GroupAntiAffinityFilter| - ensures that each instance in group is on a
   95 different host.

   167
   168 |GroupAntiAffinityFilter| its method `host_passes` returns `True` if host to
   169 place the instance on is not in a group of hosts. The group of hosts is
   170 maintained by a group name. The scheduler hint contains the group name.

    The patch set adds group support for multi-VM deployment. This is achieved
    as follows:
    1. A new hint is added: group. This will contain the name and type for the
       group. At the moment only anti-affinity is supported. In the future
       we will add network proximity. It will be extended to <name>:<type>
    2. In order to ensure that group policy will be honored for future VM
       deployments, the group is stored as system_metadata.
    3. The anti affinity is implemented by a new filter called
       GroupAntiAffinityFilter.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/22166

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/22166
Committed: http://github.com/openstack/openstack-manuals/commit/ecac0687dd33ee1c27517b53ad0e466f62040230
Submitter: Jenkins
Branch: master

commit ecac0687dd33ee1c27517b53ad0e466f62040230
Author: Tom Fifield <email address hidden>
Date: Mon Feb 18 15:57:45 2013 +1100

    Add documentation for GroupAntiAffinityFilter

    fixes bug 1128587

    With Grizzly comes the GroupAntiAffinityFilter, which ensures that
    instances in a group don't end up on the same hosts.

    This patch explains the filter and its scheduler hint

    Change-Id: I9395f07d8fdbfa9d6c705a4769c775c8e9f15ad5

[Gary Kotton (garyk)]

Hi,
Thanks for fixing this. There are a few minor comments that I would like to add:
1. Only one group ID is required. For example:
nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 --hint group=a0cf03a5-d921-4877-bb5c-86d26cf818e1 s1
The hint scheduler to find the hosts of all VM's that have group a0cf03a5-d921-4877-bb5c-86d26cf818e1 and then select a different host.
2. At the moment the group name is controlled by the user. In the futre this will be done internally (we hope).
Thanks again for documenting
Gary

[Tom Fifield (fifieldt)]

Thanks Gary! I will fix that dodgy copy/paste job ASAP.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/22294

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/22294
Committed: http://github.com/openstack/openstack-manuals/commit/432837f9765c78b36fa65a9f347ee737832f7f5b
Submitter: Jenkins
Branch: master

commit 432837f9765c78b36fa65a9f347ee737832f7f5b
Author: Tom Fifield <email address hidden>
Date: Tue Feb 19 23:33:08 2013 +1100

    Tweak GroupAntiAffinityFilter doc

    fixes bug 1128587

    Gary Kotton noted in the bug that multiple hints were being
    specified in the commandline example for the GroupAntiAffinityFilter

    This patch fixes this and adds a descriptive line about what the hint
    is used for.

    patch2 encloses group and server1 in the description in literal tags

    patch3 fixes one of the literal tags

    Change-Id: Ie15ea3deebd44e0caaf5a01d45cb90d5ed0a9d9e