Spec: Use OpenStack SDK in Nova
This is a proposal to get rid of Nova's use of python-${service}client
for $service in glance, ironic, neutron, cinder, etc and replace them
with the OpenStack SDK.
Change-Id: I9aadc5e653e9f5af0d47028ffe74eaf439658950
Implements: blueprint openstacksdk-in-nova
This commit is contained in:
Dustin Cowles
278
specs/train/approved/openstacksdk-in-nova.rst
Normal file
278
specs/train/approved/openstacksdk-in-nova.rst
Normal file
@@ -0,0 +1,278 @@
|
||||
..
|
||||
This work is licensed under a Creative Commons Attribution 3.0 Unported
|
||||
License.
|
||||
|
||||
http://creativecommons.org/licenses/by/3.0/legalcode
|
||||
|
||||
|
||||
==========================================
|
||||
Use OpenStack SDK in Nova
|
||||
==========================================
|
||||
|
||||
https://blueprints.launchpad.net/nova/+spec/openstacksdk-in-nova
|
||||
|
||||
We would like to use the OpenStack SDK to interact with other core OpenStack
|
||||
services.
|
||||
|
||||
|
||||
Problem description
|
||||
===================
|
||||
|
||||
Nova is using both ``python-${service}client`` and keystoneauth1 adapters to
|
||||
interact with other core services. Currently changes or fixes to a ``$service``
|
||||
that Nova depends on may require changes to ``python-${service}client`` before
|
||||
Nova can be brought into parity. This also requires the OpenStack SDK to be
|
||||
brought into parity as it is used for the CLI.
|
||||
|
||||
Maintenance of ``python-${service}client`` can be burdensome due to high
|
||||
technical debt in the clients. By consuming the OpenStack SDK directly, we can
|
||||
eliminate the additional dependency on the ``python-${service}client`` and
|
||||
streamline the process.
|
||||
|
||||
Use Cases
|
||||
---------
|
||||
|
||||
As a developer on OpenStack, I would like to reduce the number of areas where
|
||||
maintenance must be performed when making changes related to the use of core
|
||||
OpenStack services.
|
||||
|
||||
As a core OpenStack project, Nova should make use of other projects in reliable
|
||||
and maintainable ways. To this end, we should use the OpenStack SDK for service
|
||||
to service interaction in place of direct API or ``python-${service}client``
|
||||
implementations.
|
||||
|
||||
|
||||
Proposed change
|
||||
===============
|
||||
|
||||
This spec proposes to use the OpenStack SDK in place of
|
||||
``python-${service}client`` and other methods across Nova in three phases for
|
||||
each of the target services.
|
||||
|
||||
Target Services:
|
||||
* Ironic (python-ironicclient -> Baremetal SDK)
|
||||
* Cinder (python-cinderclient -> Block Storage SDK)
|
||||
* Glance (python-glanceclient -> Image v2 SDK)
|
||||
* Neutron (python-neutronclient -> Network SDK)
|
||||
* Placement (keystoneauth1 adapter -> OpenStack SDK Proxy)
|
||||
|
||||
The **initial phase** will consist of adding plumbing to construct an
|
||||
openstack.connection.Connection object to Nova components that interact with
|
||||
other services using a ``python-${service}client``. The service proxy from this
|
||||
connection can then be used in place of existing keystoneauth1 adapter to
|
||||
retrieve the endpoint to configure the client. This is in progress at
|
||||
[[#sdk_in_nova]_].
|
||||
|
||||
The **main phase** will be to iterate through calls to the
|
||||
``python-${service}client`` and replace them with calls into the OpenStack SDK
|
||||
until the client is no longer needed. During this phase, we will close
|
||||
feature deficiencies identified in the OpenStack SDK as necessary. See
|
||||
`OpenStack SDK Changes`_ for a list of identified deficiencies. This process is
|
||||
in progress for ``python-ironicclient`` at [[#sdk_for_ironic]_].
|
||||
|
||||
For Placement, replace the keystoneauth1 adapter returned by
|
||||
``nova.utils.get_ksa_adapter('placement')`` with the SDK's placement proxy.
|
||||
This is transparent other than a small number of changes to mocks in tests.
|
||||
This is in progress at [[#sdk_for_placement]_]. Eventually, the SDK may
|
||||
implement more support for placement. With the framework being in place, we can
|
||||
consider integrating such changes as they become available.
|
||||
|
||||
The **final phase** will simply be to remove the now-unused clients and clean
|
||||
up any remaining helpers and fixtures.
|
||||
|
||||
OpenStack SDK Changes
|
||||
---------------------
|
||||
|
||||
The OpenStack SDK includes a more complete selection of helpers for some
|
||||
services than others, but at worst provides the same primitives as a
|
||||
keystoneauth1 adapter. Development has started with Ironic, which has robust
|
||||
support within the OpenStack SDK. Other services will require additional work
|
||||
in the OpenStack SDK, or may need to be implemented using the API primitives
|
||||
provided by openstack.Proxy. It is more desirable to focus on expanding
|
||||
OpenStack SDK support for these projects rather than implementing them in Nova.
|
||||
Since there is not a spec repo for OpenStack SDK, we will try to outline the
|
||||
missing helpers by service here.
|
||||
|
||||
| **Ironic**
|
||||
| node.get_console
|
||||
| node.inject_nmi
|
||||
| node.list_volume_connectors
|
||||
| node.list_volume_targets
|
||||
| node.set_console_mode (available via ``patch_node``)
|
||||
| volume_target.create
|
||||
| volume_target.delete
|
||||
|
|
||||
| **Cinder**
|
||||
| attachments.complete
|
||||
| attachments.delete
|
||||
| attachments.update
|
||||
| volumes.attach
|
||||
| volumes.begin_detaching
|
||||
| volumes.detach
|
||||
| volumes.initialize_connection
|
||||
| volumes.migrate_volume_completion
|
||||
| volumes.reserve
|
||||
| volumes.roll_detaching
|
||||
| volumes.terminate_connection
|
||||
| volumes.unreserve
|
||||
|
|
||||
| **Glance**
|
||||
| image.add_location
|
||||
|
|
||||
| **Neutron**
|
||||
| None
|
||||
|
||||
Alternatives
|
||||
------------
|
||||
|
||||
One possibility that was considered was to replace calls into
|
||||
``python-${service}client`` with methods that invoke the ``$service`` APIs
|
||||
directly through the keystoneauth1 adapter's ``get/put/etc`` primitives. This
|
||||
would entail effectively porting the ``python-${service}client`` code into
|
||||
nova. While this would give us the opportunity to clean things up, it would
|
||||
involve a lot of low-level work like version discovery/negotiation, input
|
||||
payload construction and validation, and output processing.
|
||||
|
||||
Data model impact
|
||||
-----------------
|
||||
|
||||
None
|
||||
|
||||
REST API impact
|
||||
---------------
|
||||
|
||||
None
|
||||
|
||||
Security impact
|
||||
---------------
|
||||
|
||||
None
|
||||
|
||||
Notifications impact
|
||||
--------------------
|
||||
|
||||
None
|
||||
|
||||
Other end user impact
|
||||
---------------------
|
||||
|
||||
None
|
||||
|
||||
Performance Impact
|
||||
------------------
|
||||
|
||||
The initial phase will have minimal impact as the only change is the
|
||||
construction of the keystoneauth1 adapter by the OpenStack SDK rather than
|
||||
directly. The main phase will not likely have any difference in performance and
|
||||
the final phase should approximately offset any impact from the initial phase.
|
||||
|
||||
Other deployer impact
|
||||
---------------------
|
||||
|
||||
None
|
||||
|
||||
Developer impact
|
||||
----------------
|
||||
|
||||
By using the OpenStack SDK as the single method of contact with other services,
|
||||
the maintenance footprint can be reduced. This also moves us towards a more
|
||||
stable OpenStack SDK as more consumers generally mean more chances to find and
|
||||
resolve bugs.
|
||||
|
||||
In addition, as new methods and services are supported by the OpenStack SDK,
|
||||
introducing them to Nova should be simpler and more reliable than the current
|
||||
methods.
|
||||
|
||||
Upgrade impact
|
||||
--------------
|
||||
|
||||
None
|
||||
|
||||
|
||||
Implementation
|
||||
==============
|
||||
|
||||
Assignee(s)
|
||||
-----------
|
||||
|
||||
Primary assignee:
|
||||
dustinc <dustin.cowles@intel.com>, efried <openstack@fried.cc>
|
||||
|
||||
Other contributors:
|
||||
mordred <mordred@inaugust.com>, dtantsur <dtantsur@protonmail.com>
|
||||
|
||||
Work Items
|
||||
----------
|
||||
|
||||
1. Introduce package requirements to Nova.
|
||||
|
||||
2. Introduce plumbing for the construction of an
|
||||
openstack.connection.Connection object for each ``$service``.
|
||||
|
||||
3. For each target ``$service`` (excluding Placement), close
|
||||
deficiencies in OpenStack SDK while replace invocations into
|
||||
``python-${service}client`` one at a time, with calls into the SDK's
|
||||
``$service`` proxy.
|
||||
|
||||
* For Placement, replace the keystoneauth1 adapter with the
|
||||
SDK's placement proxy.
|
||||
|
||||
4. Remove the now-unused ``python-${service}client``, test fixtures, and other
|
||||
helpers and utils.
|
||||
|
||||
|
||||
Dependencies
|
||||
============
|
||||
|
||||
* Nova support for using keystoneauth1 config options for Cinder.
|
||||
|
||||
* https://review.opendev.org/#/c/655985/
|
||||
|
||||
|
||||
Testing
|
||||
=======
|
||||
|
||||
Existing unit tests will need to be updated to assert calls to the SDK instead
|
||||
of the client. In cases where the client call was mocked, this should be a
|
||||
matter of swapping out that mock and its assertions. No significant additional
|
||||
unit testing should be required.
|
||||
|
||||
Existing functional test cases should be adequate. Changes may be required in
|
||||
fixtures and other framework.
|
||||
|
||||
Existing integration tests should continue to function seamlessly. This will be
|
||||
the litmus test of success.
|
||||
|
||||
|
||||
Documentation Impact
|
||||
====================
|
||||
|
||||
None
|
||||
|
||||
|
||||
References
|
||||
==========
|
||||
|
||||
.. [#sdk_in_nova] https://review.opendev.org/#/c/643664/
|
||||
|
||||
.. [#sdk_for_ironic] https://review.opendev.org/#/c/642899/
|
||||
|
||||
.. [#sdk_for_placement] https://review.opendev.org/#/c/656023/
|
||||
|
||||
.. [#] http://lists.openstack.org/pipermail/openstack-discuss/2019-May/005810.html
|
||||
|
||||
.. [#] https://docs.openstack.org/openstacksdk/latest/user/config/configuration.html
|
||||
|
||||
.. [#] http://eavesdrop.openstack.org/irclogs/%23openstack-sdks/%23openstack-sdks.2019-05-20.log.html#t2019-05-20T13:48:07
|
||||
|
||||
|
||||
History
|
||||
=======
|
||||
|
||||
.. list-table:: Revisions
|
||||
:header-rows: 1
|
||||
|
||||
* - Release Name
|
||||
- Description
|
||||
* - Train
|
||||
- Introduced
|
||||
Reference in New Issue
Block a user