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masakari-specs
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vm evacuations for host recovery

https://blueprints.launchpad.net/masakari/+spec/vm-evacuations-for-host-recovery

Problem description

If one compute node failed, Masakari will evacuate the instances from the failed host.

Generally, the resources of computing nodes are gradually reduced. If a large number of hosts fail at the same time and there are not enough computing node resources, the operator needs to set the priority of instance evacuation in advance to ensure that the evacuation can be carried out in the order of priority.

When the failed compute node recovers, in order to make full use of the computing node resources and due to some instances needing to run on a specific computing node, the operator wants to migrate the instance back to the original node.

Proposed change

This spec is mainly to record instance evacuation information in the database, provide two interfaces to support obtaining all evacuation information lists and specific evacuation information details, and prepare relevant information for supporting the migration of the instances back to previously failed hosts.

  • Record instance evacuation information in the database, mainly including instance_id, notification_id, source_host, dest_host, status. The status is pending.
  • User can get evacuation information about a specific masakari notification by GET /notifications/<notification_id>/evacuations API.
  • User can get detailed information about a specific evacuation record of a particular masakari notification by GET /notifications/<notification_id>/evacuations/<evacuation_id> API.

Alternatives

None

Data model impact

The table evacuation will be added into the Masakari database.

  • created_at: Datetime.
  • updated_at: Datetime.
  • deleted_at: Datetime.
  • deleted: Boolean.
  • uuid: UUID. uuid of evacuation record.
  • notification_uuid: UUID. uuid of notification.
  • instance_uuid: UUID. uuid of instance.
  • source_host_name: String. The source compute node before the instance evacuated.
  • dest_host_name: String. The destination compute node after the instance is evacuated.
  • status: String. Represents possible statuses for notifications, such as pending, ongoing, ignored, failed and succeeded.
  • status_details: String. Store the details reason of evacuate failed/ignored.
  • priority: Numeric. Set the evacuation priority and support the evacuation of instances in order. The default value is 1.

REST API impact

Following changes will be introduced in a new API micro-version.

  • GET /notifications/<notification_id>/evacuations

    response example:

    {
    "evacuations": [
        {
            "uuid": "239f95ca-fd46-44d2-8ff8-35e8a9c94f69",
            "instance_uuid": "33826ebd-af0f-445d-833f-e06340f7ae1c",
            "notification_uuid": "c0fa1a39-c150-4b86-ae97-8fae31700c67",
            "source_host_name": "node01",
            "dest_host_name": "node02",
            "status": "pending",
            "status_details": "",
            "priority": "1"
        }
    ]
}

  • GET /notifications/<notification_id>/evacuations/<evacuation_id>

    response example:

    {
     "evacuation":
         {
             "uuid": "239f95ca-fd46-44d2-8ff8-35e8a9c94f69",
             "instance_uuid": "33826ebd-af0f-445d-833f-e06340f7ae1c",
             "notification_uuid": "c0fa1a39-c150-4b86-ae97-8fae31700c67",
             "source_host_name": "node01",
             "dest_host_name": "node02",
             "status": "pending",
             "status_details": "",
             "priority": "1"
         }
 }

Security impact

None

Notifications impact

None

Other end user impact

The python-masakariclient, masakari-dashboard and openstacksdk will be updated to support instance evacuations for host recovery in a new micro-version.

Performance Impact

None

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Primary assignee:

Historical assignee (pre-Yoga):

Work Items

  • Create the object definition, database schema, updating engine to handle this.
  • Create a new API microversion to get information for all evacuations and get detailed information about a particular evacuation.
  • Update docs for instance evacuations for host recovery
  • Update python-masakariclient, masakari-dashboard and openstacksdk to manage instance evacuations for host recovery.
  • Add unit and functional tests.

Dependencies

None

Testing

Unit and functional test is neccessary.

Add required unit and functional tests which will run in gate.

Documentation Impact

Update Masakari API reference documentation.

References

None

History

Revisions
Release Name Description
Xena Introduced
Yoga Re-proposed