Pagination for hypervisor spec

Proposal to support pagination for hypervisor.

APIImapct

Change-Id: I72b18b38cad98a415eced49fababfcc280d39f3b
Blueprint: pagination-for-hypervisor

specs/newton/approved/pagination-for-hypervisor.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+=========================
+Pagination for hypervisor
+=========================
+
+https://blueprints.launchpad.net/nova/+spec/pagination-for-hypervisor
+
+This spec is proposed to support pagination for hypervisor.
+
+Problem description
+===================
+
+When there are thousands of compute nodes, it would be slow to get the
+whole hypervisor list, and it is bad for user experience to display
+thousands of items in a table in horizon.
+
+Use Cases
+----------
+
+* Get paginated compute nodes list when there are too many items.
+
+Proposed change
+===============
+
+Changes are going to be in the following places:
+
+* New DB api `compute_node_get_all_by_filters` will be added with
+  params filters, limit and marker, so other filter
+  methods(compute_node_search_by_hypervisor, etc) also can be refactored
+  to use this new db method.
+
+* New compute node object `get_by_filters` method will be added which calls
+  the new db api `compute_node_get_all_by_filters`.
+
+* Compute api `compute_node_get_all` will be refactored.
+
+* REST API microversion will be added for hypervisors list to accept
+  pagination request.
+
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+New Hypervisors list API to support pagination:
+
+  request::
+
+      GET /v2.1/{tenant_id}/os-hypervisors?marker=2&limit=1
+
+  reponse::
+
+      {
+        "hypervisors": [
+          {
+            "hypervisor_hostname": "fake-mini",
+            "id": 3,
+            "state": "up",
+            "status": "enabled"
+          }
+        ]
+      }
+
+Security impact
+---------------
+
+None.
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+
+Performance Impact
+------------------
+
+Reduce load on horizon with help of pagination of retrieving hypervisors from
+Nova side.
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  liyingjun
+
+Work Items
+----------
+
+1. Change db api to support pagination params.
+
+2. Add compute node object method and refactor compute api.
+
+3. Add REST API microversion.
+
+Dependencies
+============
+
+None
+
+
+Testing
+=======
+
+The changes will be exercised through unit tests.
+
+Documentation Impact
+====================
+
+New REST API microversion will be added.
+
+References
+==========
+
+None