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      Copyright 2013 IBM Corp.

      Licensed under the Apache License, Version 2.0 (the "License"); you may
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============================
Keystone Event Notifications
============================

Keystone provides notifications about usage data so that 3rd party applications
can use the data for billing, monitoring, or quota purposes.  This document
describes the current inclusions and exclusions for Keystone usage
notifications.

Notifications for Create/Update/Delete Events
=============================================

A notification is sent when a resource is successfully ``created``,
``updated``, or ``deleted``. The following resource types (where a
``<resource type>`` is always a singular noun) produce notifications. For
resource types that are immutable, like trusts, notifications are only sent
on creation and deletion of that resource. Resource types that should be
immutable from a Keystone perspective will not support update operations:

- ``group``
- ``project`` (i.e. "tenant")
- ``role``
- ``user``
- ``trust`` (immutable resource - no ``updated`` notification)

The following message template is used to form a message when an operation on a
resource completes successfully::

    {
        "event_type": "identity.<resource type>.<operation>",
        "message_id": "<message ID>",
        "payload": {
            "resource_info": "<resource ID>"
        },
        "priority": "INFO",
        "publisher_id": "identity.<hostname>",
        "timestamp": "<timestamp>"
    }

Notifications for create, update and delete events are all similar to each
other, where either ``created``, ``updated`` or ``deleted`` is inserted as the
``<operation>`` in the above notification's ``event_type``.

The ``priority`` of the notification being sent is not configurable through
the Keystone configuration file. This value is defaulted to INFO for all
notifications sent in Keystone's case.

If the operation fails, the notification won't be sent, and no special error
notification will be sent.  Information about the error is handled through
normal exception paths.

Notification Example
^^^^^^^^^^^^^^^^^^^^

This is an example of a notification sent for a newly created user::

    {
        "event_type": "identity.user.created",
        "message_id": "0156ee79-b35f-4cef-ac37-d4a85f231c69",
        "payload": {
            "resource_info": "671da331c47d4e29bb6ea1d270154ec3"
        },
        "priority": "INFO",
        "publisher_id": "identity.host1234",
        "timestamp": "2013-08-29 19:03:45.960280"
    }
