Add new boot interface in Ironic
This commit proposes to add new boot interface in Ironic and refactor the current upstream deploy drivers to follow this logic. Change-Id: Ie7321b925397e3185dde654b21660a63eed0fd9f
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Ramakrishnan G
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specs/liberty/new-boot-interface.rst
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specs/liberty/new-boot-interface.rst
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..
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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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Boot Interface in Ironic
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========================
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https://blueprints.launchpad.net/ironic/+spec/new-boot-interface
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This spec talks about refactoring the boot logic out of the current Ironic
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"deploy" drivers into a new boot interface.
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Problem description
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===================
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Current we have a DeployInterface in Ironic. All the current implementations
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of this interface are responsible for two things:
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* Booting the bare metal node - both deploy ramdisk and the deployed instance.
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* Actual deployment of an image on a bare metal node.
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These are two separate functions and therefore should be abstracted
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separately. This makes it easy to mix and match various boot mechanisms (like
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PXE, iPXE, virtual media) with various deploy mechanisms (iscsi deploy, agent
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deploy and various other deploy mechanisms which may be possible like
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deploying with torrent, multicast, etc in which discussions have been
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initiated) without duplicating code.
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Proposed change
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===============
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* A new ``BootInterface`` needs to be added. The interface will recommend the
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following methods for the implementor::
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@six.add_metaclass(abc.ABCMeta)
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class BootInterface(object):
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"""Interface for inspection-related actions."""
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@abc.abstractmethod
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def get_properties(self):
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"""Return the properties of the interface.
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:returns: dictionary of <property name>:<property description>
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"""
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@abc.abstractmethod
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def validate(self, task):
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"""Validate the driver-specific info for booting.
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This method validates the driver-specific info for booting a ramdisk
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and an instance on the node. If invalid, raises an exception;
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otherwise returns None.
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:param task: a task from TaskManager.
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:raises: InvalidParameterValue
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:raises: MissingParameterValue
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"""
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@abc.abstractmethod
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def prepare_ramdisk(self, task, ramdisk_params):
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"""Prepares the boot of Ironic ramdisk.
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This method prepares the boot of the deploy ramdisk after reading
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relevant information from the node's database.
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:param task: a task from TaskManager.
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:param ramdisk_params: the options to be passed to the ironic ramdisk.
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Different interfaces might want to boot the ramdisk in different
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ways by passing parameters to them. For example,
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* When DIB ramdisk is booted to deploy a node, it takes the
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parameters iscsi_target_iqn, deployment_id, ironic_api_url, etc.
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* When Agent ramdisk is booted to deploy a node, it takes the
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parameters ipa-driver-name, ipa-api-url, root_device, etc.
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Other interfaces can make use of ramdisk_params to pass such
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information. Different implementations of boot interface will
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have different ways of passing parameters to the ramdisk.
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"""
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@abc.abstractmethod
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def clean_up_ramdisk(self, task):
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"""Tears down the boot of Ironic ramdisk.
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This method tears down the boot of the deploy ramdisk after reading
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relevant information from the node's database.
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:param task: a task from TaskManager.
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"""
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@abc.abstractmethod
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def prepare_instance(self, task):
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"""Prepares the boot of instance.
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This method prepares the boot of the instance after reading
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relevant information from the node's database.
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:param task: a task from TaskManager.
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"""
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@abc.abstractmethod
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def clean_up_instance(self, task):
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"""Tears down the boot of instance.
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This method tears down the boot of the instance after reading
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relevant information from the node's database.
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:param task: a task from TaskManager.
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"""
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* The following new implementations of ``BootInterface`` will be created.
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+ ``pxe.PXEBoot`` - Booting a bare metal node using PXE
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+ ``ipxe.IPXEBoot`` - Booting a bare metal node using iPXE
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+ ``ilo.boot.IloVirtualMediaBoot`` - Booting a bare metal node using iLO
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Virtual Media.
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.. note::
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Even though IPXEBoot and PXEBoot are in same deploy driver currently, the
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steps for preparing a bare metal to boot from PXE and iPXE are different
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(even though they share some common code). We will refactor both of them
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as separate boot interfaces. The Kilo behaviour of using only either of
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PXE or iPXE at same time will be retained - drivers will instantiate
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pxe.PXEBoot or ipxe.IPXEBoot depending on CONF.pxe.ipxe_enabled.
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* The code for the above implementations of ``BootInterface`` will be taken
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from ``pxe.PXEDeploy``, ``agent.AgentDeploy``,
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``ilo.IloVirtualMediaIscsiDeploy`` and ``ilo.IloVirtualMediaAgentDeploy``.
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These implementations of ``DeployInterface`` will be freed of any logic
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dealing with booting of bare metal node.
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* ``pxe.PXEDeploy`` will be refactored into ``pxe.PXEBoot`` and
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``iscsi_deploy.ISCSIDeploy``.
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* Each driver will mention what is the ``BootInterface`` implementation that it
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wishes to instantiate. For example, the ``pxe_ipmitool`` driver will look
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like the following::
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class PXEAndIPMIToolDriver(base.BaseDriver):
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"""PXE + IPMITool driver"""
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def __init__(self):
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self.power = ipmitool.IPMIPower()
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self.console = ipmitool.IPMIShellinaboxConsole()
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self.boot = pxe.PXEBoot()
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self.deploy = iscsi_deploy.ISCSIDeploy()
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self.management = ipmitool.IPMIManagement()
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self.vendor = pxe.VendorPassthru()
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self.inspect = discoverd.DiscoverdInspect.create_if_enabled(
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'PXEAndIPMIToolDriver')
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.. note::
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It might make sense to rename the drivers to include the boot interface as
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well as deploy interface after this is implemented. As such, this requires
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a better thought out process to rename the drivers, address issues of
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backward compatibility, etc. Hence it is out of scope of this spec. That
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can be addressed later after this is implemented.
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Alternatives
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------------
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We can continue to keep the boot and deploy logic together but this will
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lead to code duplications and unnecessary refactorings when additional deploy
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mechanisms and boot mechanisms are added in the future.
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Data model impact
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-----------------
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None.
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State Machine 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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RPC API impact
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--------------
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None.
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Client (CLI) impact
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-------------------
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None.
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Driver API impact
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-----------------
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This adds the a new ``BootInterface`` (as described above) which driver
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writers may use with the deploy drivers. ``BootInterface`` is not a
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mandatory interface.
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Nova driver 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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Other end user impact
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---------------------
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None.
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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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New driver developers adding new deploy mechanisms in Ironic will be
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encouraged to separate boot and deploy logic so that it can reused easily.
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Implementation
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==============
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Assignee(s)
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-----------
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rameshg87
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Work Items
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----------
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* Add new boot interface
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* Create ``pxe.PXEBoot``, ``ipxe.IPXEBoot`` and refactor ``pxe.PXEDeploy``
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into ``iscsi_deploy.ISCSIDeploy`` to make use of these boot interfaces.
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* Refactor ``agent.AgentDeploy`` to use new ``pxe.PXEBoot`` and
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``ipxe.IPXEBoot`` (Yes, we are adding iPXE support for agent deploy).
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* Create ``ilo.boot.IloVirtualMediaBoot``, and refactor
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``IloVirtualMediaIscsiDriver``, ``IloVirtualMediaAgentDriver`` to make
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use of the new boot interface.
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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 will be updated for the new interfaces. Since this change doesn't
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add any new functionality, the current upstream CI testing should be enough.
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Upgrades and Backwards Compatibility
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====================================
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This doesn't break out-of-tree deploy drivers. Still it will be possible
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to implement deploy drivers for provisioning bare metal nodes without a boot
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interface- i.e without separate boot and deploy interfaces. This is because
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the conductor will still be using all the published interfaces of
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``DeployInterface`` for deploying a bare metal node.
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This change proposes the addition of new optional boot interface which can be
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used as a helper for ``DeployInterface`` and refactors all upstream deploy
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drivers to follow this logic.
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Documentation Impact
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====================
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Changes to the existing interface will be documented. Also, new developer
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documentation will be updated to encourage splitting deploy logic into separate
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boot and deploy interfaces.
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References
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==========
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Not according to this spec, but a POC how it will look like:
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* https://review.openstack.org/#/c/166512/
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* https://review.openstack.org/#/c/166513/
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* https://review.openstack.org/#/c/166521/
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