Node Deployment¶
Overview¶
Node deployment is performed by the Bare Metal service to prepare a node for use by a workload. The exact work flow used depends on a number of factors, including the hardware type and interfaces assigned to a node.
Deploy Steps¶
The Bare Metal service implements deployment by collecting a list of deploy
steps to perform on a node from the Power, Deploy, Management, BIOS, and RAID
interfaces of the driver assigned to the node. These steps are then ordered by
priority and executed on the node when the node is moved to the deploying
state.
Nodes move to the deploying
state when attempting to move to the active
state (when the hardware is prepared for use by a workload). For a full
understanding of all state transitions into deployment, please see
Ironic’s State Machine.
The Bare Metal service added support for deploy steps in the Rocky release.
Order of execution¶
Deploy steps are ordered from higher to lower priority, where a larger integer is a higher priority. If the same priority is used by deploy steps on different interfaces, the following resolution order is used: Power, Management, Deploy, BIOS, and RAID interfaces.
Agent steps¶
All deploy interfaces based on ironic-python-agent (i.e. direct
, iscsi
and ansible
and any derivatives) expose the following deploy steps:
deploy.deploy
(priority 100)In this step the node is booted using a provisioning image.
deploy.write_image
(priority 80)An out-of-band (
iscsi
,ansible
) or in-band (direct
) step that downloads and writes the image to the node.deploy.tear_down_agent
(priority 40)In this step the provisioning image is shut down.
deploy.switch_to_tenant_network
(priority 30)In this step networking for the node is switched from provisioning to tenant networks.
deploy.boot_instance
(priority 20)In this step the node is booted into the user image.
Additionally, the iscsi
and direct
deploy interfaces have:
deploy.prepare_instance_boot
(priority 60)In this step the boot device is configured and the bootloader is installed.
Note
For the
ansible
deploy interface these steps are done indeploy.write_image
.
Accordingly, the following priority ranges can be used for custom deploy steps:
- > 100
Out-of-band steps to run before deployment.
- 81 to 99
In-band deploy steps to run before the image is written.
- 61 to 79
In-band deploy steps to run after the image is written but before the bootloader is installed.
- 41 to 59
In-band steps to run after the image is written the bootloader is installed.
- 21 to 39
Out-of-band steps to run after the provisioning image is shut down.
- 1 to 19
Any steps that are run when the user instance is already running.
In-band steps¶
More deploy steps can be provided by the ramdisk, see IPA hardware managers documentation for a listing.
Requesting steps¶
Starting with Bare Metal API version 1.69 user can optionally supply deploy steps for node deployment when invoking deployment or rebuilding. Overlapping steps will take precedence over Agent steps and Deploy Templates steps.
Using “baremetal” client deploy steps can be passed via --deploy-steps
argument. The argument --deploy-steps
is one of:
a JSON string
path to a JSON file whose contents are passed to the API
‘-‘, to read from stdin. This allows piping in the deploy steps.
An example by passing a JSON string:
baremetal node deploy <node> \
--deloy-steps '[{"interface": "bios", "step": "apply_configuration", "args": {"settings": [{"name": "LogicalProc", "value": "Enabled"}]}, "priority": 150}]'
Format of JSON for deploy steps argument is described in Deploy step format section.
Writing a Deploy Step¶
Please refer to Developing a new Deploy Step.
FAQ¶
What deploy step is running?¶
To check what deploy step the node is performing or attempted to perform and
failed, run the following command; it will return the value in the node’s
driver_internal_info
field:
baremetal node show <node> -f value -c driver_internal_info
The deploy_steps
field will contain a list of all remaining steps with
their priorities, and the first one listed is the step currently in progress or
that the node failed before going into deploy failed
state.
Troubleshooting¶
If deployment fails on a node, the node will be put into the deploy failed
state until the node is deprovisioned. A deprovisioned node is moved to the
available
state after the cleaning process has been performed successfully.
Strategies for determining why a deploy step failed include checking the ironic conductor logs, checking logs from the ironic-python-agent that have been stored on the ironic conductor, or performing general hardware troubleshooting on the node.
Deploy Templates¶
Starting with the Stein release, with Bare Metal API version 1.55, deploy templates offer a way to define a set of one or more deploy steps to be executed with particular sets of arguments and priorities.
Each deploy template has a name, which must be a valid trait. Traits can be either standard or custom. Standard traits are listed in the os_traits library. Custom traits must meet the following requirements:
prefixed with
CUSTOM_
contain only upper case characters A to Z, digits 0 to 9, or underscores
no longer than 255 characters in length
Deploy step format¶
An invocation of a deploy step is defined in a deploy template as follows:
{
"interface": "<name of the driver interface>",
"step": "<name of the step>",
"args": {
"<arg1>": "<value1>",
"<arg2>": "<value2>"
},
"priority": <priority of the step>
}
A deploy template contains a list of one or more such steps. Each combination of interface and step may only be specified once in a deploy template.
Matching deploy templates¶
During deployment, if any of the traits in a node’s instance_info.traits
field match the name of a deploy template, then the steps from that deploy
template will be added to the list of steps to be executed by the node.
When using the Compute service, any traits in the instance’s flavor properties
or image properties are stored in instance_info.traits
during deployment.
See Scheduling based on traits for further information on how traits are used for
scheduling when the Bare Metal service is used with the Compute service.
Note that there is no ongoing relationship between a node and any templates that are matched during deployment. The set of matching deploy templates is checked at deployment time. Any subsequent updates to or deletion of those templates will not be reflected in the node’s configuration unless it is redeployed or rebuilt. Similarly, if a node is rebuilt and the set of matching deploy templates has changed since the initial deployment, then the resulting configuration of the node may be different from the initial deployment.
Overriding default deploy steps¶
A deploy step is enabled by default if it has a non-zero default priority. A default deploy step may be overridden in a deploy template. If the step’s priority is a positive integer it will be executed with the specified priority and arguments. If the step’s priority is zero, the step will not be executed.
If a core deploy step is included in a deploy template, it can only be assigned a priority of zero to disable it.
Creating a deploy template via API¶
A deploy template can be created using the Bare Metal API:
POST /v1/deploy_templates
Here is an example of the body of a request to create a deploy template with a single step:
{
"name": "CUSTOM_HYPERTHREADING_ON",
"steps": [
{
"interface": "bios",
"step": "apply_configuration",
"args": {
"settings": [
{
"name": "LogicalProc",
"value": "Enabled"
}
]
},
"priority": 150
}
]
}
Further information on this API is available here.
Creating a deploy template via “baremetal” client¶
A deploy template can be created via the baremetal deploy template
create
command, starting with python-ironicclient
2.7.0.
The argument --steps
must be specified. Its value is one of:
a JSON string
path to a JSON file whose contents are passed to the API
‘-‘, to read from stdin. This allows piping in the deploy steps.
Example of creating a deploy template with a single step using a JSON string:
baremetal deploy template create \
CUSTOM_HYPERTHREADING_ON \
--steps '[{"interface": "bios", "step": "apply_configuration", "args": {"settings": [{"name": "LogicalProc", "value": "Enabled"}]}, "priority": 150}]'
Or with a file:
baremetal deploy template create \
CUSTOM_HYPERTHREADING_ON \
---steps my-deploy-steps.txt
Or with stdin:
cat my-deploy-steps.txt | baremetal deploy template create \
CUSTOM_HYPERTHREADING_ON \
--steps -
Example of use with the Compute service¶
Note
The deploy steps used in this example are for example purposes only.
In the following example, we first add the trait CUSTOM_HYPERTHREADING_ON
to the node represented by <node>
:
baremetal node add trait <node> CUSTOM_HYPERTHREADING_ON
We also update the flavor bm-hyperthreading-on
in the Compute
service with the following property:
openstack flavor set --property trait:CUSTOM_HYPERTHREADING_ON=required bm-hyperthreading-on
Creating a Compute instance with this flavor will ensure that the instance is
scheduled only to Bare Metal nodes with the CUSTOM_HYPERTHREADING_ON
trait.
We could then create a Bare Metal deploy template with the name
CUSTOM_HYPERTHREADING_ON
and a deploy step that enables Hyperthreading:
{
"name": "CUSTOM_HYPERTHREADING_ON",
"steps": [
{
"interface": "bios",
"step": "apply_configuration",
"args": {
"settings": [
{
"name": "LogicalProc",
"value": "Enabled"
}
]
},
"priority": 150
}
]
}
When an instance is created using the bm-hyperthreading-on
flavor, then the
deploy steps of deploy template CUSTOM_HYPERTHREADING_ON
will be executed
during the deployment of the scheduled node, causing Hyperthreading to be
enabled in the node’s BIOS configuration.
To make this example more dynamic, let’s add a second trait
CUSTOM_HYPERTHREADING_OFF
to the node:
baremetal node add trait <node> CUSTOM_HYPERTHREADING_OFF
We could also update a second flavor, bm-hyperthreading-off
, with the
following property:
openstack flavor set --property trait:CUSTOM_HYPERTHREADING_OFF=required bm-hyperthreading-off
Finally, we create a deploy template with the name
CUSTOM_HYPERTHREADING_OFF
and a deploy step that disables Hyperthreading:
{
"name": "CUSTOM_HYPERTHREADING_OFF",
"steps": [
{
"interface": "bios",
"step": "apply_configuration",
"args": {
"settings": [
{
"name": "LogicalProc",
"value": "Disabled"
}
]
},
"priority": 150
}
]
}
Creating a Compute instance with the bm-hyperthreading-off
instance will
cause the scheduled node to have Hyperthreading disabled in the BIOS during
deployment.
We now have a way to create Compute instances with different configurations, by choosing between different Compute flavors, supported by a single Bare Metal node that is dynamically configured during deployment.