Discover node properties with node-set-provision-state

Blueprint URL: https://blueprints.launchpad.net/ironic/+spec/ironic-node-properties-discovery

This proposal adds the ability to perform out-of-band node inspection and automatically update node properties using node-set-provision-state (new target ‘inspect’) process. The same set of APIs can be used by in-band properties discovery too.

Problem description

Today, Ironic is unable to automatically detect node properties which are required for scheduling or for deploy (ports creation).

The properties required by scheduler/deploy:

  • memory size
  • Disk Size
  • CPU count
  • CPU Arch
  • NIC(s) MAC address

Proposed change

The spec proposes to add these abilities:

  1. Discover the hardware properties and update the node.properties. It update all the properties with the new set values, even if the values were already set.
  2. Create ports for the NIC MAC addresses discovered. This will be done automatically after the NICS are discovered with above step. If a port already exists, it will not create a new port for that MAC address. It will take care of adding as well as deleting of the ports for the NIC changes. The ports no longer associated with the node at the time of discovery will be auto deleted. Ideally the ports shall be created for PXE enabled mac addresses, however it is each driver responsibility to get list of pxe enabled mac addresses from the hardware.

Following would be done to achieve properties inspection:

  • A new target ‘inspect’ would be added to the end point provision /v1/nodes/<uuid>/states/provision

  • When inspection is finished, puts node.provision_state as MANAGED and node.target_provision_state as None.

  • The possible new states are: INSPECTING, INSPECTFAIL, MANAGED, INSPECTED.

    Refer to [1] for more details on each state.

    Initial state : node.provision_state = INSPECTING node.target_provision_state = INSPECTED

    On Success: Final State : node.provision_state = MANAGED node.target_provision_state = None

    On Failure: Final State: node.provision_state = INSPECTFAIL node.target_provision_state = None And the error is updated at the last error.

    The provision state will be marked as INSPECTFAIL if any of the properties (scheduler required properties) could not be inspected. In this case, no properties will be updated. So its either all or none.

    A node must be in MANAGED state before initiating inspection.

  • The properties values will be overwritten with every invocation of discovery APIs. It is done so because there may be addition/deletions in the hardware between two invocations of the discovery CLI/APIs.

  • Implement timeouts for inspection. There should be a periodic task in the conductor, checking that every mapped node is not in INSPECTING state for more then inspect_timeout. This will be added as a config option in /etc/ironic/ironic.conf.

The Node.properties introspected properties will be updated whenever introspection is executed.

Hardware properties to be discovered:

The following properties would be discovered :

  • NICs mac addresses
  • cpus
  • cpu_arch
  • local_gb
  • memory_mb

The NICs data would be used to auto-create the ports. The other properties are mandatory properties for the scheduler, hence will be updated in Node.properties field.

Alternatives

The discovery can be initiated by node-create with single request to the API as below:

POST /v1/nodes/?discover=true :

In this, it requires the Nodes.post to be completely asynchronous. This would be a compatibility break for node-create as it requires a node object to be returned back. On the other hand, if discovery is done synchronously then Nodes.post will become slow. In this if Nodes.post still returns the node object without properties updated to the CLI and still do discovery in the background then Nodes.post becomes half synchronous and half asynchronous, then it will be wrong for REST API structure as the REST API shall be either synchronous or asynchronous. Hence, here node-create becomes partly synchronous and partly asynchronous. Given above reasons, this approach is not chosen.

The auto-discovery can also be used for discovering node properties but it also doesn’t provide the ability to discover properties at node-create and node-set-provision-state.

Data model impact

The discovered properties will be stored as part of the ‘properties’ field of the node. It will add two fields to the nodes table:

  1. last_inspected: It will be updated with time (when last inspection finished).
  2. inspection_started_at: It will store the start time of invocation of inspection. This will be required to calculate the inspection_timeout. It shall be cleared out after inspection finishes or timeout.

Ironic CLI impact

The node-set-provision-state target ‘inspect’ need to be defined. The synopsis will look like:

usage: ironic node-set-provision-state <UUID> inspect

REST API impact

The endpoint ‘provision’ will be enhanced with a new target:

  • PUT /v1/nodes/<uuid>/states/provision {“target”: “inspect”}
    • Changes provision_state as INSPECTING.
    • Changes target_provision_state as INSPECTED.
    • Method type: PUT
    • Normal response code: 202
    • Expected errors:
      • 404 if the node with <uuid> does not exist.
      • 400 if a conductor for the node’s driver cannot be found.
      • 409 CONFLICT, if the node cannot be transitioned to INSPECTING state.
    • URL: /v1/nodes/<uuid>/states/provision {“target”: “inspect”}
    • URL parameters: None.
    • Response body is empty if successful.
    • When inspection is finished, puts node.provision_state as MANAGED and node.target_provision_state as None.

RPC API impact

  • A new rpcapi method inspect_hardware() will be added. It will be synchronous call to the conductor and will spawn a worker thread to perform discovery. This will allow the API service to receive the acknowledgement from the conductor that the inspecting has been initiated and returns status 202 to the client.

Driver API impact

It will add new interface InspectInterface with the method inspect_hardware():

def inspect_hardware(self, task):
    """Inspect hardware.

    :param task: a task from TaskManager.

    """

A driver may choose to implement the InspectInterface.

Since InspectInterface is a standard interface, following methods will also be added:

  • validate()
  • get_properties()

Nova driver impact

None.

Security impact

None.

Other end user impact

This feature will improve user experience as users no longer need to manually update the node properties info.

Scalability impact

None.

Performance Impact

None.

Other deployer impact

The inspect_timeout is introduced in the ironic.conf under conductor. The default value for same shall be 1800 secs as required by in-band implementations.

Developer impact

The drivers who need to implement base.InspectInterface(), may decide to implement/define the abstract methods added by this proposal.

Implementation

Assignee(s)

Primary assignee:
Nisha Agarwal (launchpad ID: agarwalnisha1980, IRC login ID: Nisha)
Other Contributors:
Wan-Yen Hsu (launchpad ID : wan-yen-hsu, IRC login ID: wanyen)

Work Items

  • A new rpcapi method inspect_hardware() is added which will invoke the InspectInterface for discovering, updating node properties and creating/updating ports.
  • Add a new interface as InspectInterface to ironic driver.
  • Adding new method inspect_hardware to class InspectInterface.
  • Add new elements last_inspected and inspection_started_at to the nodes table. Ironic cli will be changed to show these fields while running ironic node-show.
  • The node.last_inspected will be updated with the last discovered time.
  • The node.inspection_started_at will be updated with the time when inspection was initiated. This will help to check the timeout for inspection. The periodic task needs to be created for the same.
  • The reference implementation will be done for iLO drivers.
  • Add a new target ‘inspect’ to node-set-provision-state for updating the hardware properties for already registered node.(ironic-client changes)

Dependencies

Requires implementation of http://specs.openstack.org/openstack/ironic-specs/specs/kilo/new-ironic-state-machine.html for the states MANAGED, INSPECTED, INSPECTING and INSPECTFAIL.

Testing

Unit tests will be added conforming to ironic testing requirements. The test suites for tempest can be written for specific implementations.

Upgrades and Backwards Compatibility

No impact.

Documentation Impact

It needs to be documented properly.