cinder/doc/source/devref/user_messages.rst

User Messages

User messages are a way to inform users about the state of asynchronous operations. One example would be notifying the user of why a volume provisioning request failed. These messages can be requested via the /messages API. All user visible messages must be defined in the permitted messages module in order to prevent sharing sensitive information with users.

Example message generation:

from cinder import context
from cinder.message import api as message_api
from cinder.message import defined_messages
from cinder.message import resource_types

self.message_api = message_api.API()

context = context.RequestContext()
project_id = '6c430ede-9476-4128-8838-8d3929ced223'
volume_id = 'f292cc0c-54a7-4b3b-8174-d2ff82d87008'

self.message_api.create(
    context,
    defined_messages.UNABLE_TO_ALLOCATE,
    project_id,
    resource_type=resource_types.VOLUME,
    resource_uuid=volume_id)

Will produce the following:

GET /v3/6c430ede-9476-4128-8838-8d3929ced223/messages
{
  "messages": [
    {
     "id": "5429fffa-5c76-4d68-a671-37a8e24f37cf",
     "event_id": "000002",
     "user_message": "No storage could be allocated for this volume request.",
     "message_level": "ERROR",
     "resource_type": "VOLUME",
     "resource_uuid": "f292cc0c-54a7-4b3b-8174-d2ff82d87008",
     "created_at": 2015-08-27T09:49:58-05:00,
     "guaranteed_until": 2015-09-27T09:49:58-05:00,
     "request_id": "req-936666d2-4c8f-4e41-9ac9-237b43f8b848",
    }
  ]
}

The Message API Module

cinder.message.api

The Resource Types Module

cinder.message.resource_types

The Permitted Messages Module

cinder.message.defined_messages