4a4fa7c184
Wrap neutron client calls used by nova to hide details of translation between arguments and JSON requests and replies and exceptions. Change-Id: I2b36bfd243e7d56950d5a7e4bbf919eb098f83c0 Blueprint: nova-neutron-refactor
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4.3 KiB
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185 lines
4.3 KiB
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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==========================================
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Wrap the Python NeutronClient
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==========================================
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https://blueprints.launchpad.net/nova/+spec/nova-neutron-refactor
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The Neutron client module used by the Neutron implementation of the
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Openstack Network API is a basic, thin wrapper around the Neutron API.
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Direct use of the module's functionality has resulted in pervasive adaptive
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code throughout the API adapter implementation. The repetitive and
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occasionally opaque nature of this code makes the implementation difficult
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to debug and maintain. Providing higher level, Nova oriented abstractions
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by wrapping the existing client:
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* Makes it easier to implement readable implementations of the networking
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API implementation.
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* Allows knowledge of the functioning of the Neutron API to be captured in
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code for reuse by all developers, independent of their Neutron API
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expertise. This is maintainable, extensible and testable in itself.
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* Provides a natural boundary to hide neutron specific details such as:
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* thrown exceptions
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* JSON request and response translation
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Problem description
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===================
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Direct use of the neutronclient module is pervasive throughout the
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implementation of the Neutron Network API adapter. This has the following
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consequences:
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* Construction of JSON requests and parsing of replies is repeated
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throughout the code.
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* Neutron specific exceptions are allowed to permeate the API boundary to
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the caller.
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* How well the Neutron client is used varies depending on the expertise of
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the respective authors. There is no mechanism for capturing best
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practices that is immediately available to developers.
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* Changes to the Neutron client can require pervasive changes to the
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adapter implementation.
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* Certain API features are only accessible through contexts with administrative
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credentials, requiring maintainers to understand which operations are
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constrained or otherwise affected by administrative credentials.
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Use Cases
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----------
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* Nova developers should not need to have direct knowledge of Neutron client
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or API specific details to perform rudimentary code changes.
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* Developers with Neutron expertise need a mechanism to capture best
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practices in an accessible and immediately useful way for themselves and
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other developers.
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* Special handling of remote call behavior can be introduced in a manageable
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and consistent fashion.
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Project Priority
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-----------------
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This refactoring addresses an issue of significant technical debt and
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is a step towards deprecating nova-network.
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Proposed change
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===============
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Provide higher level abstractions of the Neutron client calls used by Nova
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through a class (or family of classes if required). The classes hide
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construction of JSON requests, translation of replies to Nova objects and
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Neutron exceptions to Nova exceptions.
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Alternatives
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------------
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Continue to directly use the Neutron client "in-place", possibly mitigating
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code repetition through helper methods and performing ad-hoc exception
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translation through alternate means such as decorators.
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Data model impact
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-----------------
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None
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REST API impact
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---------------
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None
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Security impact
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---------------
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None.
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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None
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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None
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Developer impact
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----------------
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The results of this effort are to be consumed in the refactoring of the
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adapter so only has impact to developers working on this effort.
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignee: Brent Eagles (beagles@redhat.com)
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One or more sponsors from the core teams should have direct involvement
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in an, at minimum, advisory capacity. Particularly:
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* Dan Smith for Nova objects
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* Matt Riedemann
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* Maru Newby (Neutron)
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Primary assignee:
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* Brent Eagles beagles@redhat.com
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Work Items
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----------
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1. Create a class that provides higher level methods for neutron client.
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2. Create tempest tests to exercise wrapper.
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Dependencies
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============
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None
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Testing
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=======
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The changes will be exercised through the existing CI.
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Documentation Impact
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====================
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None
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References
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==========
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