Notification Support for Metadata Definitions

We are proposing to support notifications for events on the
Metadata Definitions Catalog.

Implements: blueprint metadefs-notifications

Change-Id: I73a0921b8cf66cbaeffed285fcbc04a9aaee3c43
Co-Authored-By: Lakshmi N Sampath <>
Co-Authored-By: Kamil Rykowski <>
Travis Tripp 2015-01-22 22:24:42 -07:00
parent 0e24c9c8b5
commit b81a9e5f0d
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This work is licensed under a Creative Commons Attribution 3.0 Unported
Notification Support for Metadata Definitions
This blueprint adds metadata definition notification support.
The implemented juno spec for metadata notifications is here for reference:
Problem description
Metadata definition resources - namespaces, objects, properties,
tags, and resource types - don't provide any notification events when
certain operations are performed on them. This doesn't allow for any
intelligent caching of the data, meaning that the only opportunity for
catalog users to be aware of changes is to continually poll. Polling is not
performant for catalog users and puts extra load on the API and database.
Proposed change
We are proposing to support notifications for events on the
Metadata Definitions Catalog.
This implementation will include the following events that will be
triggered when necessary:
* metadef_namespace.create - namespace has been created
* metadef_namespace.update - namespace has been updated
* metadef_namespace.delete - namespace has been deleted
* metadef_object.create - object has been created
* metadef_object.update - object has been updated
* metadef_object.delete - object has been deleted
* metadef_property.create - property has been created
* metadef_property.update - property has been updated
* metadef_property.delete - property has been deleted
* metadef_tag.create - tag has been created
* metadef_tag.update - tag has been updated
* metadef_tag.delete - tag has been deleted
* metadef_resource_type.create - resource type has been added to namespace
* metadef_resource_type.delete - resource type has been removed from namespace
In addition we will add a new configuration option to allow for disabling
individual notifications. It will be a comma separated list with the
following syntax::
disabled_notifications = <type>.<action>
For example, the following would disable all tag notification and property
disabled_notifications = metadef_tag,metadef_property.delete
The notifier will read this configuration and ignore notifications that are
in the disabled list.
The reason for this proposed addition is that we aren't sure whether or not
tag notifications could get too chatty for some reason. Therefore,
we'd like to give an option for deployers to disable it.
No notification support could be added. In this event,
constant polling for changes could be done. The constant polling would lead
to both latency in getting updates and extra load on the API and database.
Data model impact
REST API impact
No external API impacts will be visible. The API itself will have a notifier
added as part of the call.
Security impact
Notifications impact
A notifier will be added to the REST API calls. The notifications listed
above will be added. A new configuration option will be added to disable
specific notifications.
Other end user impact
Performance Impact
Additional notifications will be generated, but the amount of changes to
metadata definitions are not anticipated to be enough to impact performance.
However we want to add the new disabled_notifications configuration option to
allow operators to disable the notifications if they determine that are too
Other deployer impact
Deployers will have to setup listeners to received notification on metadefs
if they desire them.
Developer impact
Primary assignee:
Other contributors:
Core reviewer(s):
Other reviewer(s):
Work Items
Changes would be made to:
#. Glance v2 metadef APIs to add notifiers
#. notifer
#. gateway
Need to sync openstack/common from oslo-incubator for service module.
Unit tests will be added for all possible code with a goal of being able to
isolate functionality as much as possible.
Tempest tests will be added wherever possible.
Documentation Impact
Docs needed for new notification usage
`Current glance metadata definition catalog documentation.