Introduce ImagePropertiesFilter scheduler filter

Commit d39137fa added functionality to the ComputeFilter to filter on
architecture, hypervisor_type, and vm_mode. The existing ArchFilter
already filtered on architecture. This patch merges the ComputeFilter
functionality introduced in d39137fa with the ArchFilter to create the
ImagePropertiesFilter.  The ImagePropertiesFilter uses image properties
specified in the request_spec to filter hosts.

This patch also adds the ImagePropertiesFilter to the list of default
filters specified by the scheduler_default_filters FLAG.

Fixes LP Bug #1037339

DocImpact

Change-Id: Ifa6fccf2db266b0fe3457d58fc81fdb50ffcbc0f

1 files changed, 18 insertions, 9 deletions

diff --git a/doc/source/devref/filter_scheduler.rst b/doc/source/devref/filter_scheduler.rst
index d6ceb08ef..807fdceec 100644
--- a/doc/source/devref/filter_scheduler.rst
+++ b/doc/source/devref/filter_scheduler.rst
@@ -27,8 +27,9 @@ There are some standard filter classes to use (:mod:`nova.scheduler.filters`):
 
 * |AllHostsFilter| - frankly speaking, this filter does no operation. It
   passes all the available hosts.
-* |ArchFilter| - filters hosts based on architecture.  It passes hosts
-  that can support the architecture specified in the instance properties.
+* |ImagePropertiesFilter| - filters hosts based on properties defined
+  on the instance's image.  It passes hosts that can support the specified
+  image properties contained in the instance.
 * |AvailabilityZoneFilter| - filters hosts by availability zone. It passes
   hosts matching the availability zone specfied in the instance properties.
 * |ComputeCapabilityFilter| - checks that the capabilities provided by the
@@ -86,10 +87,17 @@ scheduler with availability zones support and can configure availability zones
 on each compute host. This classes method `host_passes` returns `True` if
 availability zone mentioned in request is the same on the current compute host.
 
-The |ArchFilter| filters hosts based on the architecture specified in the
-instance properties.  E.g., an instance might require a host that supports
-the arm architecture.  The |ArchFilter| will only pass hosts that can
-support the architecture requested by the instance.
+The |ImagePropertiesFilter| filters hosts based on the architecture,
+hypervisor type, and virtual machine mode specified in the
+instance.  E.g., an instance might require a host that supports the arm
+architecture on a qemu compute host.  The |ImagePropertiesFilter| will only
+pass hosts that can statisfy this request.  These instance
+properties are populated from properties define on the instance's image.
+E.g. an image can be decorated with these properties using
+`glance image-update img-uuid --property architecture=arm --property
+hypervisor_type=qemu`
+Only hosts that statify these requirements will pass the
+|ImagePropertiesFilter|.
 
 |ComputeCapabilitesFilter| checks if the host satisfies any 'extra specs'
 specfied on the instance type.  The 'extra specs' can contain key/value pairs,
@@ -160,11 +168,12 @@ The default values for these settings in nova.conf are:
 ::
 
     --scheduler_available_filters=nova.scheduler.filters.standard_filters
-    --scheduler_default_filters=RamFilter,ComputeFilter,AvailabilityZoneFilter,ComputeCapabilityFilter
+    --scheduler_default_filters=RamFilter,ComputeFilter,AvailabilityZoneFilter,ComputeCapabilityFilter,ImagePropertiesFilter
 
 With this configuration, all filters in `nova.scheduler.filters`
 would be available, and by default the |RamFilter|, |ComputeFilter|,
-|AvailabilityZoneFilter|, and |ComputeCapabilityFilter| would be used.
+|AvailabilityZoneFilter|, |ComputeCapabilityFilter|, and
+|ImagePropertiesFilter| would be used.
 
 If you want to create **your own filter** you just need to inherit from
 |BaseHostFilter| and implement one method:
@@ -278,7 +287,7 @@ P.S.: you can find more examples of using Filter Scheduler and standard filters
 in :mod:`nova.tests.scheduler`.
 
 .. |AllHostsFilter| replace:: :class:`AllHostsFilter <nova.scheduler.filters.all_hosts_filter.AllHostsFilter>`
-.. |ArchFilter| replace:: :class:`ArchFilter <nova.scheduler.filters.arch_filter.ArchFilter>`
+.. |ImagePropertiesFilter| replace:: :class:`ImagePropertiesFilter <nova.scheduler.filters.image_props_filter.ImagePropertiesFilter>`
 .. |AvailabilityZoneFilter| replace:: :class:`AvailabilityZoneFilter <nova.scheduler.filters.availability_zone_filter.AvailabilityZoneFilter>`
 .. |BaseHostFilter| replace:: :class:`BaseHostFilter <nova.scheduler.filters.BaseHostFilter>`
 .. |ComputeCapabilitiesFilter| replace:: :class:`ComputeCapabilitiesFilter <nova.scheduler.filters.compute_capabilities_filter.ComputeCapabilitiesFilter>`