Update glance documentation for trait support

Required traits on the image allow specifying a server to be
built only on compute nodes which express those traits. The
Nova Scheduler has been updated to look at the image trait
properties when selecting compute nodes.

Updating the documentation for glance to explain the same.

Documentation is similar to flavor required traits documentation available
here: https://docs.openstack.org/nova/latest/user/flavors.html#extra-specs

Change-Id: I716821abf44238eecc9c4a1d198d8a31b87dedce
Implements: blueprint glance-image-traits
This commit is contained in:
Arvind Nadendla 2018-07-11 17:29:31 -07:00
parent f3496591ae
commit b30ed486ae
1 changed files with 26 additions and 0 deletions

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@ -230,6 +230,32 @@ Here is a list of useful image properties and the values they expect.
- The ID of image stored in the Image service that should be used as the
ramdisk when booting an AMI-style image.
- Valid image ID.
* - All
- ``trait:<trait_name>``
- Added in the Rocky release. Functionality is similar to traits specified
in `flavor extra specs <https://docs.openstack.org/nova/latest/user/flavors.html#extra-specs>`_.
Traits allow specifying a server to build on a compute node with the set
of traits specified in the image. The traits are associated with the
resource provider that represents the compute node in the Placement API.
The syntax of specifying traits is **trait:<trait_name>=value**, for
example:
* trait:HW_CPU_X86_AVX2=required
* trait:STORAGE_DISK_SSD=required
The nova scheduler will pass required traits specified on the image to
the Placement API to include only resource providers that can satisfy
the required traits. Traits for the resource providers can be managed
using the `osc-placement plugin. <https://docs.openstack.org/osc-placement/latest/index.html>`_
Image traits are used by the nova scheduler even in cases of volume
backed instances, if the volume source is an image with traits.
- Only valid value is ``required``, any other value is invalid.
* ``required`` - <trait_name> is required on the resource provider that
represents the compute node on which the image is launched.
* - All
- ``vm_mode``
- The virtual machine mode. This represents the host/guest ABI