openstack
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glance
Code Issues Proposed changes

Clarify the Glance/metadefs relationship 

I've answered a few questions recently for people who assumed that
since the metadefs service lives on the Glance endpoint, metadefs
have some kind of special relationship to images.  I think the
metadefs section of the api-ref makes it clear that this is not the
case (though it's not mentioned at all on the Images part of the
api-ref).  So here's an attempt to clarify issue (without being too
intrusive) right at the top of the Glance docs landing page.

Change-Id: I3dfbb09862acedb265a5a4557749bf52f6add5f4
This commit is contained in:
Brian Rosmaita 2018-10-08 16:47:55 -04:00
parent e5e1cc439c
commit eceb4f54c6
1 changed files with 25 additions and 1 deletions
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26
doc/source/index.rst
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@ -23,7 +23,10 @@ About Glance
The Image service (glance) project provides a service where users can upload
and discover data assets that are meant to be used with other services.
This currently includes images and metadata definitions.
This currently includes *images* and *metadata definitions*.
Images
------
Glance image services include discovering, registering, and
retrieving virtual machine (VM) images. Glance has a RESTful API that allows
@ -35,6 +38,27 @@ VM images made available through Glance can be stored in a variety of
locations from simple filesystems to object-storage systems like the
OpenStack Swift project.
Metadata Definitions
--------------------
Glance hosts a *metadefs* catalog. This provides the OpenStack community
with a way to programmatically determine various metadata key names and
valid values that can be applied to OpenStack resources.
Note that what we're talking about here is simply a *catalog*; the keys and
values don't actually do anything unless they are applied to individual
OpenStack resources using the APIs or client tools provided by the services
responsible for those resources.
It's also worth noting that there is no special relationship between the
Image Service and the Metadefs Service. If you want to apply the keys and
values defined in the Metadefs Service to images, you must use the Image
Service API or client tools just as you would for any other OpenStack
service.
Design Principles
-----------------
Glance, as with all OpenStack projects, is written with the following design
guidelines in mind: