ironic/doc/source/deploy/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, 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. (Prior to Mitaka, this option was named 'clean_nodes'.):

[conductor]
automated_clean=true

This will enable the default set of cleaning steps, based on your hardware and ironic drivers. If you're using an agent* driver, 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 drivers, the following resolution order is used: Power, Management, Deploy, 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.

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 driver'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 ironic CLI

Manual cleaning is supported in the ironic node-set-provision-state command, starting with python-ironicclient 1.2.

The target/verb is 'clean' and 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.

Keep in mind that manual cleaning is only supported in API version 1.15 and higher.

Examples of doing this with a JSON string:

ironic --ironic-api-version 1.15 node-set-provision-state \
clean --clean-steps '[{"interface": "deploy", "step": "erase_devices_metadata"}]'

ironic --ironic-api-version 1.15 node-set-provision-state \
clean --clean-steps '[{"interface": "deploy", "step": "erase_devices"}]'

Or with a file:

ironic --ironic-api-version 1.15 node-set-provision-state \
clean --clean-steps my-clean-steps.txt

Or with stdin:

cat my-clean-steps.txt | ironic --ironic-api-version 1.15 \
node-set-provision-state clean --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 the Bare Metal service for 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 driver. Currently, all the drivers using ironic-python-agent ramdisk support in-band cleaning. By default, ironic-python-agent ships with a minimal cleaning configuration, only erasing disks. However, with this ramdisk, 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 driver. Which steps are performed depends on the driver and hardware.

For Out-of-Band cleaning operations supported by iLO drivers, 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 drivers, the following resolution order is used: Power, Management, Deploy, and RAID interfaces.

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 agent_ilo driver, use the following configuration option:

[ilo]
clean_priority_erase_devices=0

The generic hardware manager first tries to perform ATA disk erase by using hdparm utility. If ATA disk erase is not supported, it performs software based disk erase using 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

What cleaning step is running?

To check what cleaning step the node is performing or attempted to perform and failed, either query the node endpoint for the node or run ironic node-show $node_ident and look in the driver_internal_info field. 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 disks with support for cryptographic ATA Security Erase, as typically the erase_devices step in the deploy driver 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.

Troubleshooting

If cleaning fails on a node, the node will be put into clean failed state and placed in maintenance mode, to prevent ironic from taking actions on the node.

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: ironic node-set-provision-state manage. 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
ironic node-set-maintenance $node_ident false

# Now, make the node available for scheduling by nova
ironic node-set-provision-state $node_ident provide

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