This service plugin synchronizes ML2 mechanism driver agents' resource
information to Placement. To use this service an agent must add
'resource_provider_bandwidths' to the 'configurations' field of its
RPC heartbeat. It also may add 'resource_provider_inventory_defaults'
to fine tune Placement inventory parameters. Again to use this service a
mechanism driver must implement get_standrd_device_mappings() and allocate
a UUID as mechanism driver property 'resource_provider_uuid5_namespace'.
The synchronization is triggered by:
* any new agent object in the DB
* restart of an agent (via 'start_flag' in the RPC heartbeat)
* if an agent's 'resources_synced' attribute is not True (None/False)
The latter should autoheal transient errors of the synchronization
process. That is if a sync attemp fails then we store
resources_synced=False which triggers a sync retry at each new heartbeat
message until a sync attempt finally succeeds and we can set
resources_synced=True.
Since this code functionally depends on ML2 we can also consider making
it part of ML2, but at the moment it is a service plugin for better
decoupling. Even if you load the service plugin the logic gracefully
degrades for heartbeat messages not containing resource provider info.
If needed the sync can be forced in multiple ways. First, if you restart
an agent then the RPs belonging to that agent will be re-synced. You may
also delete the agent by 'openstack network agent delete' and let the
next heartbeat message re-create the agent object. On re-creation the
RPs belonging to that agent will be re-synced. On the other hand a
neutron-server restart does not trigger a re-sync in any way. Depending
on the trade-off between the admin's needs to force re-syncs and the
performance of (not absolutely necessary) Placement updates re-sync
conditions may be further fine tuned.
Example config for neutron-server:
neutron.conf:
[DEFAULT]
service_plugins = placement
Change-Id: Ia1ff6f7559ab77913ddb9c3b134420a401b8eb43
Co-Authored-By: Lajos Katona <lajos.katona@ericsson.com>
Depends-On: https://review.openstack.org/586567
Partial-Bug: #1578989
See-Also: https://review.openstack.org/502306 (nova spec)
See-Also: https://review.openstack.org/508149 (neutron spec)
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