f6ef197473
As of now, the glossary defined in our documentation reflects the current state of the codebase. In order to avoid any discrepancy between the codebase and each definition, the objective here is to gather both in a single place and link it into the rst documentation via a custom directive. Also re-aligned the requirements with liberty for doc. Change-Id: I3089fd9f948b948115672f10937b1500b96ce180 Partial-Bug: #1526671
120 lines
4.9 KiB
Python
120 lines
4.9 KiB
Python
# -*- encoding: utf-8 -*-
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# Copyright (c) 2015 b<>com
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#
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# Authors: Jean-Emile DARTOIS <jean-emile.dartois@b-com.com>
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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"""
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A :ref:`Cluster Data Model <cluster_data_model_definition>` is a logical
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representation of the current state and topology of the
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:ref:`Cluster <cluster_definition>`
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:ref:`Managed resources <managed_resource_definition>`.
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It is represented as a set of
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:ref:`Managed resources <managed_resource_definition>`
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(which may be a simple tree or a flat list of key-value pairs)
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which enables Watcher :ref:`Strategies <strategy_definition>` to know the
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current relationships between the different
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:ref:`resources <managed_resource_definition>`) of the
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:ref:`Cluster <cluster_definition>` during an :ref:`Audit <audit_definition>`
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and enables the :ref:`Strategy <strategy_definition>` to request information
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such as:
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- What compute nodes are in a given
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:ref:`Availability Zone <availability_zone_definition>`
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or a given :ref:`Host Aggregate <host_aggregates_definition>` ?
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- What :ref:`Instances <instance_definition>` are hosted on a given compute
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node ?
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- What is the current load of a compute node ?
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- What is the current free memory of a compute node ?
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- What is the network link between two compute nodes ?
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- What is the available bandwidth on a given network link ?
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- What is the current space available on a given virtual disk of a given
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:ref:`Instance <instance_definition>` ?
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- What is the current state of a given :ref:`Instance <instance_definition>`?
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- ...
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In a word, this data model enables the :ref:`Strategy <strategy_definition>`
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to know:
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- the current topology of the :ref:`Cluster <cluster_definition>`
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- the current capacity for each
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:ref:`Managed resource <managed_resource_definition>`
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- the current amount of used/free space for each
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:ref:`Managed resource <managed_resource_definition>`
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- the current state of each
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:ref:`Managed resources <managed_resource_definition>`
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In the Watcher project, we aim at providing a generic and very basic
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:ref:`Cluster Data Model <cluster_data_model_definition>` for each
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:ref:`Goal <goal_definition>`, usable in the associated
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:ref:`Strategies <strategy_definition>` through some helper classes in order
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to:
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- simplify the development of a new
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:ref:`Strategy <strategy_definition>` for a given
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:ref:`Goal <goal_definition>` when there already are some existing
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:ref:`Strategies <strategy_definition>` associated to the same
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:ref:`Goal <goal_definition>`
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- avoid duplicating the same code in several
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:ref:`Strategies <strategy_definition>` associated to the same
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:ref:`Goal <goal_definition>`
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- have a better consistency between the different
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:ref:`Strategies <strategy_definition>` for a given
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:ref:`Goal <goal_definition>`
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- avoid any strong coupling with any external
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:ref:`Cluster Data Model <cluster_data_model_definition>`
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(the proposed data model acts as a pivot data model)
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There may be various
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:ref:`generic and basic Cluster Data Models <cluster_data_model_definition>`
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proposed in Watcher helpers, each of them being adapted to achieving a given
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:ref:`Goal <goal_definition>`:
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- For example, for a
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:ref:`Goal <goal_definition>` which aims at optimizing the network
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:ref:`resources <managed_resource_definition>` the
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:ref:`Strategy <strategy_definition>` may need to know which
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:ref:`resources <managed_resource_definition>` are communicating together.
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- Whereas for a :ref:`Goal <goal_definition>` which aims at optimizing thermal
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and power conditions, the :ref:`Strategy <strategy_definition>` may need to
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know the location of each compute node in the racks and the location of each
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rack in the room.
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Note however that a developer can use his/her own
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:ref:`Cluster Data Model <cluster_data_model_definition>` if the proposed data
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model does not fit his/her needs as long as the
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:ref:`Strategy <strategy_definition>` is able to produce a
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:ref:`Solution <solution_definition>` for the requested
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:ref:`Goal <goal_definition>`.
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For example, a developer could rely on the Nova Data Model to optimize some
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compute resources.
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The :ref:`Cluster Data Model <cluster_data_model_definition>` may be persisted
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in any appropriate storage system (SQL database, NoSQL database, JSON file,
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XML File, In Memory Database, ...).
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"""
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import abc
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import six
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@six.add_metaclass(abc.ABCMeta)
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class BaseClusterModelCollector(object):
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@abc.abstractmethod
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def get_latest_cluster_data_model(self):
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raise NotImplementedError()
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