Feature/diskless boot

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @stackhpc/openstack

.github/workflows/tag-and-release.yml

@@ -0,0 +1,12 @@
+---
+name: Tag & Release
+'on':
+  push:
+    branches:
+      - stackhpc/2025.1
+permissions:
+  actions: read
+  contents: write
+jobs:
+  tag-and-release:
+    uses: stackhpc/.github/.github/workflows/tag-and-release.yml@main

.github/workflows/tox.yml

@@ -0,0 +1,7 @@
+---
+name: Tox Continuous Integration
+'on':
+  pull_request:
+jobs:
+  tox:
+    uses: stackhpc/.github/.github/workflows/tox.yml@main

doc/source/admin/interfaces/deploy.rst

@@ -121,6 +121,66 @@ To disable the conductor-side conversion completely, set
    [DEFAULT]
    force_raw_images = False
 
+Autodetect support
+------------------
+
+The ``direct`` deploy interface supports being auto-detected by the
+``autodetect`` deploy interface (see :ref:`autodetect-deploy` for details).
+The ``direct`` interface will always claim to support switching to it for
+deployment regardless of the supplied node information. This makes it
+appropriate to use as the last fallback value in the
+``autodetect_deploy_interfaces`` configuration option.
+
+.. _autodetect-deploy:
+
+Autodetect deploy
+=================
+
+The ``autodetect`` deploy interface automatically selects the most appropriate
+concrete deploy interface based on image metadata and node configuration. This
+simplifies node configuration by eliminating the need to manually specify
+different deploy interfaces for different image types.
+
+When a deployment begins, the autodetect interface inspects the image and node
+configuration, then switches to the most appropriate deploy interface from the
+configured list. The detection logic checks interfaces in priority order using
+each interface's ``supports_deploy()`` method. The first interface that
+returns ``True`` is selected. If no interfaces are detected as supported, the
+last interface in the configured list is used as a fallback.
+
+You can specify this deploy interface when creating or updating a node::
+
+    baremetal node create --driver ipmi --deploy-interface autodetect
+    baremetal node set <NODE> --deploy-interface autodetect
+
+Configuration
+-------------
+
+The autodetect interface uses the ``autodetect_deploy_interfaces``
+configuration option to control which interfaces can be auto-selected and
+their priority order. The default configuration is:
+
+.. code-block:: ini
+
+   [DEFAULT]
+   autodetect_deploy_interfaces = ramdisk,bootc,direct
+
+This example configuration checks :doc:`Ramdisk deploy </admin/ramdisk-boot>` first
+(for nodes with ``kernel``/``ramdisk`` or ``boot_iso`` in ``instance_info``),
+then :ref:`Bootc deploy <bootc-deploy>` (for OCI container images), and falls
+back to :ref:`Direct deploy <direct-deploy>` for standard disk images.
+
+.. note::
+   The order of interfaces in the configuration list matters. Interfaces are
+   checked in the order listed, and the first supported interface is selected.
+   The last interface in the list serves as the fallback if no other interface
+   is detected as supported.
+
+.. note::
+   After deployment teardown, the node's deploy interface is automatically
+   restored to ``autodetect`` from whatever concrete interface was used during
+   deployment.
+
 .. _ansible-deploy:
 
 Ansible deploy
@@ -178,6 +238,16 @@ The ramdisk interface is intended to provide a mechanism to "deploy" an
 instance where the item to be deployed is in reality a ramdisk. It is
 documented separately, see :doc:`/admin/ramdisk-boot`.
 
+Autodetect support
+------------------
+
+The ``ramdisk`` deploy interface supports being auto-detected by the
+``autodetect`` deploy interface (see :ref:`autodetect-deploy` for details).
+It checks whether the node's ``instance_info`` contains ``kernel`` and
+``ramdisk`` (without an ``image_source``), or whether ``boot_iso`` is set.
+When either condition is met, autodetect will select the ``ramdisk`` deploy
+interface.
+
 .. _custom-agent-deploy:
 
 Custom agent deploy
@@ -254,6 +324,16 @@ to enable download from the remote image registry, which is part of the
 support for retrieval of artifacts from OCI Container registires.
 This parameter is ``image_pull_secret``.
 
+Autodetect support
+------------------
+
+The ``bootc`` deploy interface supports being auto-detected by the
+``autodetect`` deploy interface (see :ref:`autodetect-deploy` for details). It
+checks whether the image source URL is an OCI container image (``oci://``
+URL), then introspects the image registry to confirm the artifact is a
+container image (OCI artifacts are handled by the ``direct`` deploy
+interface).
+
 Caveats
 -------
 

doc/source/admin/ramdisk-boot.rst

@@ -40,6 +40,13 @@ or update an existing node:
 You can also use it with :ref:`redfish virtual media
 <redfish-virtual-media-ramdisk>` instead of iPXE.
 
+Alternatively, if the node uses the ``autodetect`` deploy interface, the
+ramdisk interface is selected automatically when ``kernel`` and ``ramdisk``
+are set in ``instance_info`` (without an ``image_source``), or when
+``boot_iso`` is set. To enable this, add ``ramdisk`` to the
+``autodetect_deploy_interfaces`` configuration option. See
+:ref:`autodetect-deploy` for details.
+
 Creating a ramdisk
 ------------------
 
@@ -125,6 +132,98 @@ ISO images are also cached across deployments, similarly to how it is done for
 normal instance images. The URL together with the last modified response header
 are used to determine if an image needs updating.
 
+Using with Nova (Glance images)
+-------------------------------
+
+When deploying ramdisk nodes through Nova, the user creates a Glance image with
+``kernel_id`` and ``ramdisk_id`` properties — the same AMI-style pattern used
+for partition images. Nova sets ``image_source`` in the node's ``instance_info``
+and Ironic resolves the kernel and ramdisk from Glance automatically.
+
+#. Upload the kernel to Glance:
+
+   .. code-block:: shell
+
+      openstack image create my-ramdisk-kernel --public \
+        --disk-format raw --container-format bare \
+        --file my-ramdisk.kernel
+
+   Store the image UUID as ``MY_KERNEL_UUID``.
+
+#. Upload the ramdisk (initramfs) to Glance:
+
+   .. code-block:: shell
+
+      openstack image create my-ramdisk-initrd --public \
+        --disk-format raw --container-format bare \
+        --file my-ramdisk.initramfs
+
+   Store the image UUID as ``MY_RAMDISK_UUID``.
+
+#. Create the Glance image with ``kernel_id`` and ``ramdisk_id`` properties.
+   Since the ramdisk deploy interface does not write to disk, the disk image
+   file is not used — an empty placeholder file is sufficient.
+
+   Include ``ironic_ramdisk_deploy=True`` so that the deploy interface
+   autodetect mechanism can distinguish this image from a partition image
+   (which also carries ``kernel_id`` / ``ramdisk_id``):
+
+   .. code-block:: shell
+
+      touch /tmp/placeholder
+      openstack image create my-ramdisk-image --public \
+        --disk-format raw --container-format bare \
+        --property kernel_id=$MY_KERNEL_UUID \
+        --property ramdisk_id=$MY_RAMDISK_UUID \
+        --property ironic_ramdisk_deploy=True \
+        --file /tmp/placeholder
+
+#. Boot a Nova instance using this image:
+
+   .. code-block:: shell
+
+      openstack server create --image my-ramdisk-image \
+        --flavor my-baremetal-flavor my-ramdisk-instance
+
+Alternative: Using a boot ISO in Glance
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Instead of separate kernel and ramdisk images, you can reference a single boot
+ISO stored in Glance via the ``boot_iso_id`` property:
+
+#. Upload the boot ISO to Glance:
+
+   .. code-block:: shell
+
+      openstack image create my-ramdisk-boot-iso --public \
+        --disk-format iso --container-format bare \
+        --file my-ramdisk.iso
+
+   Store the image UUID as ``MY_BOOT_ISO_UUID``.
+
+#. Create the Glance image with the ``boot_iso_id`` property:
+
+   .. code-block:: shell
+
+      touch /tmp/placeholder
+      openstack image create my-ramdisk-image --public \
+        --disk-format raw --container-format bare \
+        --property boot_iso_id=$MY_BOOT_ISO_UUID \
+        --file /tmp/placeholder
+
+#. Boot a Nova instance as above:
+
+   .. code-block:: shell
+
+      openstack server create --image my-ramdisk-image \
+        --flavor my-baremetal-flavor my-ramdisk-instance
+
+.. note::
+   The disk image file attached to the Glance image is **not** used by the
+   ramdisk deploy interface. Only the kernel and ramdisk referenced by
+   ``kernel_id`` / ``ramdisk_id``, or the ISO referenced by ``boot_iso_id``,
+   are booted.
+
 Limitations
 -----------
 

doc/source/install/configure-glance-images.rst

@@ -84,6 +84,12 @@ the Image service for each one as it is generated.
        kernel_id=$MY_VMLINUZ_UUID --property \
        ramdisk_id=$MY_INITRD_UUID --file my-image.qcow2
 
+- For images used with the *ramdisk deploy interface* (e.g. when deploying
+  ramdisk nodes through Nova), you can use either ``kernel_id`` /
+  ``ramdisk_id`` properties (with ``ironic_ramdisk_deploy=True`` to
+  distinguish from partition images) or a single ``boot_iso_id`` property
+  pointing to an ISO in Glance. See :doc:`/admin/ramdisk-boot` for details.
+
 Deploy ramdisk images
 ~~~~~~~~~~~~~~~~~~~~~
 

ironic/conductor/cleaning.py

@@ -50,6 +50,9 @@ def do_node_clean(task, clean_steps=None, disable_ramdisk=False):
         node.clean_step = None
         node.save()
 
+        # Switch back to original interface, if necessary
+        task.driver.deploy.restore_interface(task)
+
         task.process_event('done')
         how = ('API' if node.automated_clean is False else 'configuration')
         LOG.info('Automated cleaning is disabled via %(how)s, node %(node)s '

ironic/conductor/deployments.py

@@ -161,6 +161,8 @@ def start_deploy(task, manager, configdrive=None, event='deploy',
             instance_info = node.instance_info
             instance_info.pop('kernel', None)
             instance_info.pop('ramdisk', None)
+            instance_info.pop('boot_iso', None)
+            instance_info.pop('original_image_source', None)
             node.instance_info = instance_info
     else:
         # NOTE(JayF): Don't apply lessee when rebuilding
@@ -173,6 +175,9 @@ def start_deploy(task, manager, configdrive=None, event='deploy',
         node.save()
 
     try:
+        # Give the deploy interface the opportunity to switch interfaces
+        task.driver.deploy.switch_interface(task)
+
         task.driver.power.validate(task)
         task.driver.deploy.validate(task)
         utils.validate_instance_info_traits(task.node)

ironic/conductor/utils.py

@@ -600,6 +600,9 @@ def cleaning_error_handler(task, logmsg, errmsg=None, traceback=False,
 
     node.save()
 
+    # Switch back to original interface, if necessary
+    task.driver.deploy.restore_interface(task)
+
     if set_fail_state and node.provision_state != states.CLEANFAIL:
         target_state = states.MANAGEABLE if manual_clean else None
         task.process_event('fail', target_state=target_state)

ironic/conf/default.py

@@ -129,10 +129,23 @@
     cfg.StrOpt('default_console_interface',
                help=_DEFAULT_IFACE_HELP.format('console')),
     cfg.ListOpt('enabled_deploy_interfaces',
-                default=['direct', 'ramdisk'],
+                default=['autodetect', 'direct', 'ramdisk'],
                 help=_ENABLED_IFACE_HELP.format('deploy')),
     cfg.StrOpt('default_deploy_interface',
                help=_DEFAULT_IFACE_HELP.format('deploy')),
+    cfg.ListOpt('autodetect_deploy_interfaces',
+                default=['ramdisk', 'direct'],
+                help=_('List of deploy interfaces that the '
+                       'autodetect deploy interface is allowed to '
+                       'switch to. The order of interfaces in the list '
+                       'indicates the order support will be checked for,'
+                       'with the first interface having the highest '
+                       'priority. The last interface in the list will be '
+                       'chosen if no interfaces are detected as supported. '
+                       '"ramdisk" and "bootc" have detection support '
+                       'and "direct" is an appropriate fallback for '
+                       'most cases. All interfaces listed here must '
+                       'also be in "enabled_deploy_interfaces".')),
     cfg.ListOpt('enabled_firmware_interfaces',
                 default=['no-firmware'],
                 help=_ENABLED_IFACE_HELP.format('firmware')),

ironic/drivers/base.py

@@ -621,6 +621,40 @@ def prepare_service(self, task):
         """
         pass
 
+    def switch_interface(self, task):
+        """Optionally switch the interface to use for deployment.
+
+        This method is called at the beginning of deployment before validation
+        to accommodate interfaces which auto-detect another interface to use
+        for deployment.
+
+        :param task: A TaskManager instance containing the node to act on.
+        :raises: InvalidParameterValue if the interface is not enabled.
+        """
+        pass
+
+    def restore_interface(self, task):
+        """Restore the original deploy interface for the node.
+
+        This restores the deploy interface to the original interface
+        in case it was changed by switch_interface.
+
+        :param task: a TaskManager instance containing the node to act on.
+        """
+        pass
+
+    def supports_deploy(self, task):
+        """Check if deploy is supported for the given node by this interface.
+
+        By default interfaces will claim to support deploy. Interfaces
+        which can infer actual support using (for example) node instance_info
+        should override this method.
+
+        :param task: A TaskManager instance containing the node to act on.
+        :returns: boolean, whether deploy is supported.
+        """
+        return True
+
 
 class BootInterface(BaseInterface):
     """Interface for boot-related actions."""

ironic/drivers/generic.py

@@ -20,6 +20,7 @@
 from ironic.drivers.modules import agent
 from ironic.drivers.modules import agent_power
 from ironic.drivers.modules.ansible import deploy as ansible_deploy
+from ironic.drivers.modules import autodetect
 from ironic.drivers.modules import fake
 from ironic.drivers.modules import inspector
 from ironic.drivers.modules import ipxe
@@ -49,9 +50,10 @@ def supported_boot_interfaces(self):
     @property
     def supported_deploy_interfaces(self):
         """List of supported deploy interfaces."""
-        return [agent.AgentDeploy, ansible_deploy.AnsibleDeploy,
-                ramdisk.RamdiskDeploy, pxe.PXEAnacondaDeploy,
-                agent.BootcAgentDeploy, agent.CustomAgentDeploy]
+        return [autodetect.AutodetectDeploy, agent.AgentDeploy,
+                ansible_deploy.AnsibleDeploy, ramdisk.RamdiskDeploy,
+                pxe.PXEAnacondaDeploy, agent.BootcAgentDeploy,
+                agent.CustomAgentDeploy]
 
     @property
     def supported_inspect_interfaces(self):