ironic/doc/source/admin/cleaning.rst

Node cleaning

Overview

Ironic provides two modes for node cleaning: automated and manual.

Automated cleaning is automatically performed before the first workload has been assigned to a node and when hardware is recycled from one workload to another.

Manual cleaning must be invoked by the operator.

Automated cleaning

When hardware is recycled from one workload to another, ironic performs automated cleaning on the node to ensure it's ready for another workload. This ensures the tenant will get a consistent bare metal node deployed every time.

Ironic implements automated cleaning by collecting a list of cleaning 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 cleaning state, if automated cleaning is enabled.

With automated cleaning, nodes move to cleaning state when moving from active -> available state (when the hardware is recycled from one workload to another). Nodes also traverse cleaning when going from manageable -> available state (before the first workload is assigned to the nodes). For a full understanding of all state transitions into cleaning, please see states.

Ironic added support for automated cleaning in the Kilo release.

Enabling automated cleaning

To enable automated cleaning, ensure that your ironic.conf is set as follows:

[conductor]
automated_clean=true

This will enable the default set of cleaning steps, based on your hardware and ironic hardware types used for nodes. This includes, by default, erasing all of the previous tenant's data.

You may also need to configure a Cleaning Network.

Cleaning steps

Cleaning steps used for automated cleaning are ordered from higher to lower priority, where a larger integer is a higher priority. In case of a conflict between priorities across interfaces, the following resolution order is used: Power, Management, Deploy, BIOS, and RAID interfaces.

You can skip a cleaning step by setting the priority for that cleaning step to zero or 'None'.

You can reorder the cleaning steps by modifying the integer priorities of the cleaning steps.

See How do I change the priority of a cleaning step? for more information.

Storage cleaning options

Clean steps specific to storage are erase_devices, erase_devices_metadata and (added in Yoga) erase_devices_express.

erase_devices aims to ensure that the data is removed in the most secure way available. On devices that support hardware assisted secure erasure (many NVMe and some ATA drives) this is the preferred option. If hardware-assisted secure erasure is not available and if [deploy]/continue_if_disk_secure_erase_fails is set to True, cleaning will fall back to using shred to overwrite the contents of the device. Otherwise cleaning will fail. It is important to note that erase_devices may take a very long time (hours or even days) to complete, unless fast, hardware assisted data erasure is supported by all the devices in a system. Generally, it is very difficult (if possible at all) to recover data after performing cleaning with erase_devices.

erase_devices_metadata clean step doesn't provide as strong assurance of irreversible destruction of data as erase_devices. However, it has the advantage of a reasonably quick runtime (seconds to minutes). It operates by destroying metadata of the storage device without erasing every bit of the data itself. Attempts of restoring data after running erase_devices_metadata may be successful but would certainly require relevant expertise and specialized tools.

Lastly, erase_devices_express combines some of the perks of both erase_devices and erase_devices_metadata. It attempts to utilize hardware assisted data erasure features if available (currently only NVMe devices are supported). In case hardware-asssisted data erasure is not available, it falls back to metadata erasure for the device (which is identical to erase_devices_metadata). It can be considered a time optimized mode of storage cleaning, aiming to perform as thorough data erasure as it is possible within a short period of time. This clean step is particularly well suited for environments with hybrid NVMe-HDD storage configuration as it allows fast and secure erasure of data stored on NVMes combined with equally fast but more basic metadata-based erasure of data on HDDs. erase_devices_express is disabled by default. In order to use it, the following configuration is recommended.

[deploy]/erase_devices_priority=0
[deploy]/erase_devices_metadata_priority=0
[conductor]/clean_step_priority_override=deploy.erase_devices_express:5

This ensures that erase_devices and erase_devices_metadata are disabled so that storage is not cleaned twice and then assigns a non-zero priority to erase_devices_express, hence enabling it. Any non-zero priority specified in the priority override will work.

Also [deploy]/enable_nvme_secure_erase should not be disabled (it is on by default).

Manual cleaning

Manual cleaning is typically used to handle long running, manual, or destructive tasks that an operator wishes to perform either before the first workload has been assigned to a node or between workloads. When initiating a manual clean, the operator specifies the cleaning steps to be performed. Manual cleaning can only be performed when a node is in the manageable state. Once the manual cleaning is finished, the node will be put in the manageable state again.

Ironic added support for manual cleaning in the 4.4 (Mitaka series) release.

Setup

In order for manual cleaning to work, you may need to configure a Cleaning Network.

Starting manual cleaning via API

Manual cleaning can only be performed when a node is in the manageable state. The REST API request to initiate it is available in API version 1.15 and higher:

PUT /v1/nodes/<node_ident>/states/provision

(Additional information is available here.)

This API will allow operators to put a node directly into cleaning provision state from manageable state via 'target': 'clean'. The PUT will also require the argument 'clean_steps' to be specified. This is an ordered list of cleaning steps. A cleaning step is represented by a dictionary (JSON), in the form:

{
    "interface": "<interface>",
    "step": "<name of cleaning step>",
    "args": {"<arg1>": "<value1>", ..., "<argn>": <valuen>}
}

The 'interface' and 'step' keys are required for all steps. If a cleaning step method takes keyword arguments, the 'args' key may be specified. It is a dictionary of keyword variable arguments, with each keyword-argument entry being <name>: <value>.

If any step is missing a required keyword argument, manual cleaning will not be performed and the node will be put in clean failed provision state with an appropriate error message.

If, during the cleaning process, a cleaning step determines that it has incorrect keyword arguments, all earlier steps will be performed and then the node will be put in clean failed provision state with an appropriate error message.

An example of the request body for this API:

{
  "target":"clean",
  "clean_steps": [{
    "interface": "raid",
    "step": "create_configuration",
    "args": {"create_nonroot_volumes": false}
  },
  {
    "interface": "deploy",
    "step": "erase_devices"
  }]
}

In the above example, the node's RAID interface would configure hardware RAID without non-root volumes, and then all devices would be erased (in that order).

Starting manual cleaning via "openstack metal" CLI

Manual cleaning is available via the baremetal node clean command, starting with Bare Metal API version 1.15.

The argument --clean-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 clean steps. Using '-' to signify stdin is common in Unix utilities.

The following examples assume that the Bare Metal API version was set via the OS_BAREMETAL_API_VERSION environment variable. (The alternative is to add --os-baremetal-api-version 1.15 to the command.):

export OS_BAREMETAL_API_VERSION=1.15

Examples of doing this with a JSON string:

baremetal node clean <node> \
    --clean-steps '[{"interface": "deploy", "step": "erase_devices_metadata"}]'

baremetal node clean <node> \
    --clean-steps '[{"interface": "deploy", "step": "erase_devices"}]'

Or with a file:

baremetal node clean <node> \
    --clean-steps my-clean-steps.txt

Or with stdin:

cat my-clean-steps.txt | baremetal node clean <node> \
    --clean-steps -

Cleaning Network

If you are using the Neutron DHCP provider (the default) you will also need to ensure you have configured a cleaning network. This network will be used to boot the ramdisk for in-band cleaning. You can use the same network as your tenant network. For steps to set up the cleaning network, please see configure-cleaning.

In-band vs out-of-band

Ironic uses two main methods to perform actions on a node: in-band and out-of-band. Ironic supports using both methods to clean a node.

In-band

In-band steps are performed by ironic making API calls to a ramdisk running on the node using a deploy interface. Currently, all the deploy interfaces support in-band cleaning. By default, ironic-python-agent ships with a minimal cleaning configuration, only erasing disks. However, you can add your own cleaning steps and/or override default cleaning steps with a custom Hardware Manager.

Out-of-band

Out-of-band are actions performed by your management controller, such as IPMI, iLO, or DRAC. Out-of-band steps will be performed by ironic using a power or management interface. Which steps are performed depends on the hardware type and hardware itself.

For Out-of-Band cleaning operations supported by iLO hardware types, refer to ilo_node_cleaning.

FAQ

How are cleaning steps ordered?

For automated cleaning, cleaning steps are ordered by integer priority, where a larger integer is a higher priority. In case of a conflict between priorities across hardware interfaces, the following resolution order is used:

1. Power interface
2. Management interface
3. Deploy interface
4. BIOS interface
5. RAID interface

For manual cleaning, the cleaning steps should be specified in the desired order.

How do I skip a cleaning step?

For automated cleaning, cleaning steps with a priority of 0 or None are skipped.

How do I change the priority of a cleaning step?

For manual cleaning, specify the cleaning steps in the desired order.

For automated cleaning, it depends on whether the cleaning steps are out-of-band or in-band.

Most out-of-band cleaning steps have an explicit configuration option for priority.

Changing the priority of an in-band (ironic-python-agent) cleaning step requires use of a custom HardwareManager. The only exception is erase_devices, which can have its priority set in ironic.conf. For instance, to disable erase_devices, you'd set the following configuration option:

[deploy]
erase_devices_priority=0

To enable/disable the in-band disk erase using ilo hardware type, use the following configuration option:

[ilo]
clean_priority_erase_devices=0

The generic hardware manager first identifies whether a device is an NVMe drive or an ATA drive so that it can attempt a platform-specific secure erase method. In case of NVMe drives, it tries to perform a secure format operation by using the nvme-cli utility. This behavior can be controlled using the following configuration option (by default it is set to True):

[deploy]
enable_nvme_secure_erase=True

In case of ATA drives, it tries to perform ATA disk erase by using the hdparm utility.

If neither method is supported, it performs software based disk erase using the shred utility. By default, the number of iterations performed by shred for software based disk erase is 1. To configure the number of iterations, use the following configuration option:

[deploy]
erase_devices_iterations=1

Overriding step priority

[conductor]clean_step_priority_override is a new configuration option which allows specifying priority of each step using multiple configuration values:

[conductor]
clean_step_priority_override=deploy.erase_devices_metadata:123
clean_step_priority_override=management.reset_bios_to_default:234
clean_step_priority_override=management.clean_priority_reset_ilo:345

This parameter can be specified as many times as required to define priorities for several cleaning steps - the values will be combined.

What cleaning step is running?

To check what cleaning 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_ident -f value -c driver_internal_info

The clean_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 clean failed state.

Should I disable automated cleaning?

Automated cleaning is recommended for ironic deployments, however, there are some tradeoffs to having it enabled. For instance, ironic cannot deploy a new instance to a node that is currently cleaning, and cleaning can be a time consuming process. To mitigate this, we suggest using NVMe drives with support for NVMe Secure Erase (based on nvme-cli format command) or ATA drives with support for cryptographic ATA Security Erase, as typically the erase_devices step in the deploy interface takes the longest time to complete of all cleaning steps.

Why can't I power on/off a node while it's cleaning?

During cleaning, nodes may be performing actions that shouldn't be interrupted, such as BIOS or Firmware updates. As a result, operators are forbidden from changing power state via the ironic API while a node is cleaning.

Advanced topics

Parent Nodes

The concept of a parent_node is where a node is configured to have a "parent", and allows for actions upon the parent, to in some cases take into account child nodes. Mainly, the concept of executing clean steps in relation to child nodes.

In this context, a child node is primarily intended to be an embedded device with it's own management controller. For example "SmartNIC's" or Data Processing Units (DPUs) which may have their own management controller and power control.

The relationship between a parent node and a child node is established on the child node. Example:

baremetal node set --parent-node <parent_node_uuid> <child_node_uuid>

Child Node Clean Step Execution

You can execute steps which perform actions on child nodes. For example, turn them on (via step power_on), off (via step power_off), or to signal a BMC controlled reboot (via step reboot).

For example, if you need to explicitly power off child node power, before performing another step, you can articulate it with a step such as:

[{
  "interface": "power",
  "step": "power_off",
  "execute_on_child_nodes": True,
  "limit_child_node_execution": ['f96c8601-0a62-4e99-97d6-1e0d8daf6dce']
},
{
  "interface": "deploy",
  "step": "erase_devices"
}]

As one would imagine, this step will power off a singular child node, as a limit has been expressed to a singular known node, and that child node's power will be turned off via the management interface. Afterwards, the erase_devices step will be executed on the parent node.

Note

While the deployment step framework also supports the execute_on_child_nodes and limit_child_node_execution parameters, all of the step frameworks have a fundamental limitation in that child node step execution is intended for synchronous actions which do not rely upon the ironic-python-agent running on any child nodes. This constraint may be changed in the future.

Troubleshooting

If cleaning fails on a node, the node will be put into clean failed state. If the failure happens while running a clean step, the node is also placed in maintenance mode to prevent ironic from taking actions on the node. The operator should validate that no permanent damage has been done to the node and no processes are still running on it before removing the maintenance mode.

Note

Older versions of ironic may put the node to maintenance even when no clean step has been running.

Nodes in clean failed will not be powered off, as the node might be in a state such that powering it off could damage the node or remove useful information about the nature of the cleaning failure.

A clean failed node can be moved to manageable state, where it cannot be scheduled by nova and you can safely attempt to fix the node. To move a node from clean failed to manageable:

baremetal node manage $node_ident

You can now take actions on the node, such as replacing a bad disk drive.

Strategies for determining why a cleaning step failed include checking the ironic conductor logs, viewing logs on the still-running ironic-python-agent (if an in-band step failed), or performing general hardware troubleshooting on the node.

When the node is repaired, you can move the node back to available state, to allow it to be scheduled by nova.

# First, move it out of maintenance mode
baremetal node maintenance unset $node_ident

# Now, make the node available for scheduling by nova
baremetal node provide $node_ident

The node will begin automated cleaning from the start, and move to available state when complete.