Node servicing

Overview

In order to better enable operators to modify existing nodes, Ironic has introduced the model of Node Servicing, where you can take a node in active state, modify it using steps similar to Deploy Steps or manual cleaning through the Cleaning subsystem.

For more information on cleaning, please see Node cleaning.

Major differences

Service steps do not contain an automatic execution model, which is intrinisc to the standard deployment and “automated” cleaning workflows. This may change at some point in the future.

This also means that while a priority value can be supplied, it is not presently utilized.

Similarities to Cleaning and Deployment

Similar to Clean and Deploy steps, when invoked an operator can validate the current running steps by viewing the driver_internal_info field looking for a service_steps field. The current step being executed can be viewed using the baremetal node service_step field, which is a top level field.

Service steps are internally decorated on driver interface methods utilizing decorator. This means service steps do not automatically expose clean and deploy steps to be executed at any time. The Ironic development team took a cautious and intentional approach behind methods which are decorated. Besides, some clean and deployment steps are geared explicitly for operating in that mode, and would not be suitable to be triggered outside of the original workflow it was designed for use in.

Available Steps

Executing Service Steps

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

Starting manual cleaning via API

Servicing can only be performed when a node is in the active provision state. The REST API request to initiate it is available in API version 1.87 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 servicing provision state from active provision state via ‘target’: ‘service’. The PUT will also require the argument ‘service_steps’ to be specified. This is an ordered list of steps. A step is represented by a dictionary (JSON), in the form:

{
    "interface": "<interface>",
    "step": "<name of 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, servicing will not be performed and the node will be put in service failed provision state with an appropriate error message.

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

An example of the request body for this API:

{
  "target":"service",
  "sevice_steps": [{
    "interface": "raid",
    "step": "apply_configuration",
    "args": {"create_nonroot_volumes": True}
  },
  {
    "interface": "vendor",
    "step": "send_raw"
    "args": {"raw_bytes": "0x00 0x00 0x00 0x00"}
  }]
}

In the above example, the node’s RAID interface would apply the set RAID configuration, and then the vendor interface’s send_raw step would be called to send a raw command to the BMC. Please note, send_raw is only available for the ipmi hardware type.

Starting servicing via “openstack baremetal” CLI

Servicing is available via the baremetal node service command, starting with Bare Metal API version 1.87.

The argument --service-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.

Examples of doing this with a JSON string:

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

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

Or with a file:

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

Or with stdin:

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

Available Steps in Ironic

ipmi hardware type

vendor.send_raw

This step is covered in the IPMI driver documentation and is usable as a service step in addition to a deploy step.

redfish hardware type

bios.apply_configuration

This is covered in the BIOS Configuration configuration documentation as it started as a cleaning step. It is a standardized cross-interface name.

management.update_firmware

This step is covered in the Redfish driver and is intended to facilitate firmware updates via the BMC.

raid.apply_configuration

This step is covered in the Redfish driver and is intended to facilitate applying raid configuration.

raid.delete_configuration

This step is covered in the Redfish driver and is intended to delete configuration.

Agent

raid.apply_configuration

This is the standardized RAID passthrough interface for the agent, and can be leveraged like other RAID interfaces.

Available steps in Ironic-Python-Agent

Note

Steps available from the agent will be populated once support has merged in the agent to expose the steps to the ironic deployment.

Servicing Network

If you are using the Neutron DHCP provider (the default) you will also need to ensure you have configured a servicing network. This network will be used to boot the ramdisk for in-band service operations. This setting is configured utilizing the [neutron]servicing_network configuration parameter.