mogan-specs/specs/pike/approved/server-group-api-extension.rst
Zhenguo Niu 95bb712a76 Add server group support
This spec introduces server group concept to Mogan.

Partially Implements: bp server-group-api-extension
Change-Id: Iab90dcb0a5d080f204c8f923e4bc4bd0675d9ebe
2017-08-25 10:25:59 +08:00

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============
Server Group
============
https://blueprints.launchpad.net/mogan/+spec/server-group-api-extension
This spec proposes adding server group support to mogan. It's quite like
nova's server groups, but nova only support *host* based affinity or
anti-affinity, which is not fit for bare metals.
Problem description
===================
Currently, it is not possible to schedule some servers to the same or
different location or group like what nova server group does for virtual
machines.
Use Cases
---------
* As a tenant, I would like to schedule servers on the same group of bare metal
nodes.
* As a tenant, I would like to schedule servers on the different group of bare
metal nodes.
Proposed change
===============
We proposes to add a special aggregate metadata key *affinity_zone*. You may
define it as failure domains(e.g., by power circuit, rack, room, etc), or
whatever you want to make affinity and anity-affinity happen in such groups.
All bare metals nodes are in a same affinity zone by default.
* A new mogan.objects.ServerGroup object would be added to the object model.
* Add a set of APIs to allow tenants manage the server groups, including
create, delete, show and list APIs.
* Allow users to specify server group when claiming servers.
* Add logic to scheduler to check the server group plicy and members affinity
relationship to filter nodes.
Alternatives
------------
None
Data model impact
-----------------
The proposed change will be adding the following fields to the server group
object with their data type and default value for migrations.
+-----------------------+--------------+-----------------+
| Field Name | Field Type | Default Value |
+=======================+==============+=================+
| id | Integer | None |
+-----------------------+--------------+-----------------+
| uuid | UUID | None |
+-----------------------+--------------+-----------------+
| user_id | UUID | None |
+-----------------------+--------------+-----------------+
| project_id | UUID | None |
+-----------------------+--------------+-----------------+
| name | String | None |
+-----------------------+--------------+-----------------+
| policies | ListOfString | None |
+-----------------------+--------------+-----------------+
| members | ListOfString | None |
+-----------------------+--------------+-----------------+
REST API impact
---------------
REST API will be changed as part of this change.
- To create a new server group, a user will::
POST /v1/server_groups
With a body containing the JSON description of the server group.
JSON Schema::
{
"type": "object",
"properties": {
'name': {'type': 'string', 'minLength': 1, 'maxLength': 255},
'policies': {
'type': 'array',
'items': [{
'type': 'string',
'enum': ['anti-affinity', 'affinity']}],
'uniqueItems': True,
'additionalItems': False,
},
},
'required': ['name', 'policies'],
'additionalProperties': False,
}
- To list server groups, a user will::
GET /v1/server_groups
- To show server group details, a user will::
GET /v1/server_groups/{servergroup_id}
- To delete a server group, a user will::
DELETE /v1/server_groups/{servergroup_id}
Security impact
---------------
None
Notifications impact
--------------------
None
Other end user impact
---------------------
None
Performance Impact
------------------
None
Other deployer impact
---------------------
None
Developer impact
----------------
None
Implementation
==============
Assignee(s)
-----------
Primary assignee:
liusheng
Other contributors:
zhenguo
Work Items
----------
* Add server group object with the proposed fields.
* Add REST API to support server group management.
* Change scheduler to consider the specified server group.
* Allow users to specify server group when claiming servers.
* Change CLI to support server group management.
* Add UT and docs.
Dependencies
============
None
Testing
=======
Unit Testing will be added.
Documentation Impact
====================
Docs about server groups will be added.
References
==========
None