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Taikun OCP Guide

Table of Contents

Node adoption

Overview

As part of hardware inventory lifecycle management, it is not an
unreasonable need to have the capability to be able to add hardware that
should be considered “in-use” by the Bare Metal service, that may have
been deployed by another Bare Metal service installation or deployed via
other means.

As such, the node adoption feature allows a user to define a node as
active while skipping the available and
deploying states, which will prevent the node from being
seen by the Compute service as ready for use.

This feature is leveraged as part of the state machine workflow,
where a node in manageable can be moved to
active state via the provision_state verb
adopt. To view the state transition capabilities, please
see states.

Note

For deployments using Ironic in conjunction with Nova, Ironic’s node
adoption feature is not suitable. If you need to adopt production nodes
into Ironic and Nova, you can find a high-level recipe
in adoption_with_nova.

How it works

A node initially enrolled begins in the enroll state. An
operator must then move the node to manageable state, which
causes the node’s power interface to be validated. Once in
manageable state, an operator can then explicitly choose to
adopt a node.

Adoption of a node results in the validation of its boot
interface, and upon success the process leverages what is referred to as
the “takeover” logic. The takeover process is intended for conductors to
take over the management of nodes for a conductor that has failed.

The takeover process involves the deploy interface’s
prepare and take_over methods being called.
These steps take specific actions such as downloading and staging the
deployment kernel and ramdisk, ISO image, any required boot image, or
boot ISO image and then places any PXE or virtual media configuration
necessary for the node should it be required.

The adoption process makes no changes to the physical node, with the
exception of operator supplied configurations where virtual media is
used to boot the node under normal circumstances. An operator should
ensure that any supplied configuration defining the node is sufficient
for the continued operation of the node moving forward.

Possible Risk

The main risk with this feature is that supplied configuration may
ultimately be incorrect or invalid which could result in potential
operational issues:

  • rebuild verb – Rebuild is intended to allow a user
    to re-deploy the node to a fresh state. The risk with adoption is that
    the image defined when an operator adopts the node may not be the valid
    image for the pre-existing configuration.

    If this feature is utilized for a migration from one deployment to
    another, and pristine original images are loaded and provided, then
    ultimately the risk is the same with any normal use of the
    rebuild feature, the server is effectively wiped.

  • When deleting a node, the deletion or cleaning processes may fail
    if the incorrect deployment image is supplied in the configuration as
    the node may NOT have been deployed with the supplied image and driver
    or compatibility issues may exist as a result.

    Operators will need to be cognizant of that possibility and should
    plan accordingly to ensure that deployment images are known to be
    compatible with the hardware in their environment.

  • Networking – Adoption will assert no new networking configuration
    to the newly adopted node as that would be considered modifying the
    node.

    Operators will need to plan accordingly and have network
    configuration such that the nodes will be able to network boot.

How to use

Note

The power state that the ironic-conductor observes upon the first
successful power state check, as part of the transition to the
manageable state will be enforced with a node that has been
adopted. This means a node that is in power off state will,
by default, have the power state enforced as power off
moving forward, unless an administrator actively changes the power state
using the Bare Metal service.

Requirements

Requirements for use are essentially the same as to deploy a
node:

  • Sufficient driver information to allow for a successful power
    management validation.
  • Sufficient instance_info to pass deploy interface preparation.

Each driver may have additional requirements dependent upon the
configuration that is supplied. An example of this would be defining a
node to always boot from the network, which will cause the conductor to
attempt to retrieve the pertinent files. Inability to do so will result
in the adoption failing, and the node being placed in the
adopt failed state.

Example

This is an example to create a new node, named testnode,
with sufficient information to pass basic validation in order to be
taken from the manageable state to active
state:

# Explicitly set the client API version environment variable to
# 1.17, which introduces the adoption capability.
export OS_BAREMETAL_API_VERSION=1.17

baremetal node create --name testnode \
    --driver ipmi \
    --driver-info ipmi_address=<ip_address> \
    --driver-info ipmi_username=<username> \
    --driver-info ipmi_password=<password> \
    --driver-info deploy_kernel=<deploy_kernel_id_or_url> \
    --driver-info deploy_ramdisk=<deploy_ramdisk_id_or_url>

baremetal port create <node_mac_address> --node <node_uuid>

baremetal node set testnode \
    --instance-info image_source="http://localhost:8080/blankimage"

baremetal node manage testnode --wait

baremetal node adopt testnode --wait

Note

In the above example, the image_source setting must reference a valid
image or file, however that image or file can ultimately be empty.

Note

The above example utilizes a capability that defines the boot
operation to be local. It is recommended to define the node as such
unless network booting is desired.

Note

The above example will fail a re-deployment as a fake image is
defined and no instance_info/image_checksum value is defined. As such
any actual attempt to write the image out will fail as the
image_checksum value is only validated at time of an actual deployment
operation.

Note

A user may wish to assign an instance_uuid to a node, which could be
used to match an instance in the Compute service. Doing so is not
required for the proper operation of the Bare Metal service.

baremetal node set <node name or uuid> –instance-uuid
<uuid>

Note

In Newton, coupled with API version 1.20, the concept of a
network_interface was introduced. A user of this feature may wish to add
new nodes with a network_interface of noop and then change
the interface at a later point and time.

Troubleshooting

Should an adoption operation fail for a node, the error that caused
the failure will be logged in the node’s last_error field
when viewing the node. This error, in the case of node adoption, will
largely be due to failure of a validation step. Validation steps are
dependent upon what driver is selected for the node.

Any node that is in the adopt failed state can have the
adopt verb re-attempted. Example:

baremetal node adopt <node name or uuid>

If a user wishes to abort their attempt at adopting, they can then
move the node back to manageable from
adopt failed state by issuing the manage verb.
Example:

baremetal node manage <node name or uuid>

If all else fails the hardware node can be removed from the Bare
Metal service. The node delete command, which is
not the same as setting the provision state to
deleted, can be used while the node is in
adopt failed state. This will delete the node without
cleaning occurring to preserve the node’s current state. Example:

baremetal node delete <node name or uuid>

Adoption with Nova

Since there is no mechanism to create bare metal instances in Nova
when nodes are adopted into Ironic, the node adoption feature described
above cannot be used to add in production nodes to deployments which use
Ironic together with Nova.

One option to add in production nodes to an Ironic/Nova deployment is
to use the fake drivers. The overall idea is that for Nova the nodes are
instantiated normally to ensure the instances are properly created in
the compute project while Ironic does not touch them.

Here are some high level steps to be used as a guideline:

  • create a bare metal flavor and a hosting project for the
    instances
  • enroll the nodes into Ironic, create the ports, move them to
    manageable
  • change the hardware type and the interfaces to fake drivers
  • provide the nodes to make them available
  • one by one, add the nodes to the placement aggregate and create
    instances
  • change the hardware type and the interfaces back to the real
    ones

Make sure you change the drivers to the fake ones
before providing the nodes as cleaning will otherwise
wipe your production servers!

The reason to make all nodes available and manage access via the
aggregate is that this is much faster than providing nodes one by one
and relying on the resource tracker to find them. Enabling them one by
one is required to make sure the instance name and the (pre-adoption)
name of the server match.

The above recipe does not cover Neutron which, depending on your
deployment, may need to be handled in addition.

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