ae35f97b43
There are many references to review.openstack.org, and while the redirect should work, we can also go ahead and fix them. Change-Id: Ic82bde84617c461aba1e4a02b3fc562a90c99a6e
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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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Introduce Driver Capabilities
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==========================================
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This spec introduces inspectable (via Ironic API) capabilities for Ironic
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drivers.
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https://blueprints.launchpad.net/ironic/+spec/driver-capabilities
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Problem description
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===================
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Capabilities are required for at least these use cases:
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* Scheduling on a node with a proper driver.
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E.g. with time we start implementing variants of deployment that are not
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supported by all drivers, including:
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* Whole-disk vs partition deployment [1].
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* Using configdrive for deployment [2].
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* Using ephemeral partitions.
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We need to take all these differences into account when scheduling. Failure
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to do so will lead to errors on the late stage of deployment or even (as with
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whole-disk) to the wrong deployment.
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Ironic should be able to aggregate driver capabilities into node
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capabilities to expose them to the scheduler. (Not addressed by this spec.)
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* Examining driver features.
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As we are introducing more vendor-specific things, we need some way to find
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out, if one is supported by a given driver. Driver capabilities would
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enable 3rd-party tools to inspect support of particular feature
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by particular driver.
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Proposed change
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===============
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* Introduce get_capabilities() call to all driver interfaces, return value
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being set of strings.
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* Introduce get_capabilities() call to ``BaseDriver``, defaulting to union
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of capabilities of all interfaces.
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* Publish capabilities as ``/v1/drivers/{name}/capabilities`` REST endpoint.
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With the above changes, a developer could use the Ironic API to go through the
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list of drivers and inspect their capabilities.
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Alternatives
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------------
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* Obviously the best solution would be to have all drivers implement the same
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set of capabilities. Unfortunately, it's not realistic. E.g. some drivers
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(like IPMI) are more generic than the other (like ILO and DRAC), but we
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don't want to artificialy limit what more specific drivers can expose.
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Data model impact
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-----------------
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None. For now we expect driver capabilities to be a hardcoded constant.
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REST API impact
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---------------
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* ``/v1/drivers/{name}/capabilities``
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* Get driver capabilities.
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* Method type GET.
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* Normal http response code(s): 200
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* Expected error http response code(s)
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* 404 - driver not found.
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* Parameter: ``name`` - driver name
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* Body: None
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* Response: JSON list of strings.
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* A corresponding change in the client library and CLI is necessary, e.g.
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::
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$ ironic driver-get-capabilities pxe_ipmitool
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RPC API impact
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--------------
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* New synchronous RPC method ``get_driver_capabilities``, taking
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``driver_name``, returning list of capabilities.
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Driver API impact
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-----------------
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* New method ``get_capabilities`` added to all interfaces, defaulting to
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returning an empty set.
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* New method ``get_capabilities`` added to the ``BaseDriver``, defaulting to
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returning a union of ``get_capabilities`` results for all interfaces.
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Change is backward-compatible.
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Nova driver impact
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------------------
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None for now. This spec is a starting point to implement hardware capabilities
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for nodes [3], which will affect Nova driver.
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Security 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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* New CLI command: ``ironic driver-get-capabilities <driver name>``
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Scalability 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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* Driver developers can override ``get_capabilities`` to provide information
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about additional capabilities.
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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:
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None
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Work Items
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----------
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* Add ``get_capabilities`` to all interfaces.
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* Add ``get_capabilities`` to the ``BaseDriver``.
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* Add ``get_driver_capabilities`` to the RPC API.
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* Add new REST API.
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* Research whether to add capabilities to existing drivers.
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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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Unit tests
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Upgrades and Backwards Compatibility
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====================================
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No upgrade impact
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Documentation Impact
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====================
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* New API should be documented.
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* Driver documentation should mention the new method.
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References
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==========
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* [1] https://review.opendev.org/97150
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* [2] https://review.opendev.org/99235
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* [3] https://review.opendev.org/131272
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