ironic/doc/source/contributor/states.rst
Sam Betts 3940e8cf21 Add documentation describing each Ironic state
During a recent doc rework it was highighted that we should stop
linking to the ironic spec for the state machine and instead move that
information into the real documentation. This patch moves the
description about each state from that document into the states
documentation alongside the state machine.

Change-Id: If0cba97f7d7f6e3b7c4f4009ca61c7bcdec470e0
2017-09-25 13:44:31 +01:00

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7.2 KiB
ReStructuredText

.. _states:
======================
Ironic's State Machine
======================
State Machine Diagram
=====================
The diagram below shows the provisioning states that an Ironic node goes
through during the lifetime of a node. The diagram also depicts the events
that transition the node to different states.
Stable states are highlighted with a thicker border. All transitions from
stable states are initiated by API requests. There are a few other
API-initiated-transitions that are possible from non-stable states.
The events for these API-initiated transitions are indicated with '(via API)'.
Internally, the conductor initiates the other transitions (depicted in gray).
.. figure:: ../images/states.svg
:width: 660px
:align: left
:alt: Ironic state transitions
State Descriptions
==================
enroll (stable state)
This is the state that all nodes start off in when created using API version
1.11 or newer. When a node is in the ``enroll`` state, the only thing ironic
knows about it is that it exists, and ironic cannot take any further action
by itself. Once a node has its driver/interfaces and their required
information set in ``node.driver_info``, the node can be transitioned to the
``verifying`` state by setting the node's provision state using the
``manage`` verb.
verifying
ironic will validate that it can manage the node using the information given
in ``node.driver_info`` and with either the driver/hardware type and
interfaces it has been assigned. This involves going out and confirming that
the credentials work to access whatever node control mechanism they talk to.
manageable (stable state)
Once ironic has verified that it can manage the node using the
driver/interfaces and credentials passed in at node create time, the node
will be transitioned to the ``manageable`` state. From ``manageable``, nodes
can transition to:
* ``manageable`` (through ``cleaning``) by setting the node's provision state
using the ``clean`` verb.
* ``manageable`` (through ``inspecting``) by setting the node's provision
state using the ``inspect`` verb.
* ``available`` (through ``cleaning`` if automatic cleaning is enabled) by
setting the node's provision state using the ``provide`` verb.
* ``active`` (through ``adopting``) by setting the node's provision state
using the ``adopt`` verb.
``manageable`` is the state that a node should be moved into when any updates
need to be made to it such as changes to fields in driver_info and updates to
networking information on ironic ports assigned to the node.
``manageable`` is also the only stable state that can be transitioned to,
from these failure states:
* ``adopt failed``
* ``clean failed``
* ``inspect failed``
inspecting
``inspecting`` will utilize node introspection to update hardware-derived
node properties to reflect the current state of the hardware. If
introspection fails, the node will transition to ``inspect failed``.
inspect failed
This is the state a node will move into when inspection of the node fails. From
here the node can transitioned to:
* ``inspecting`` by setting the node's provision state using the ``inspect``
verb.
* ``manageable`` by setting the node's provision state using the ``manage``
verb
cleaning
Nodes in the ``cleaning`` state are being scrubbed and reprogrammed into a
known configuration.
When a node is in the ``cleaning`` state it means that the conductor is
executing the clean step (for out-of-band clean steps) or preparing the
environment (building PXE configuration files, configuring the DHCP, etc)
to boot the ramdisk for running in-band clean steps.
clean wait
Just like the ``cleaning`` state, the nodes in the ``clean wait`` state are
being scrubbed and reprogrammed. The difference is that in the ``clean wait``
state the conductor is waiting for the ramdisk to boot or the clean step
which is running in-band to finish.
The cleaning process of a node in the ``clean wait`` state can be interrupted
by setting the node's provision state using the ``abort`` verb if the task
that is running allows it.
available (stable state)
After nodes have been successfully preconfigured and cleaned, they are moved
into the ``available`` state and are ready to be provisioned. From
``available``, nodes can transition to:
* ``active`` (through ``deploying``) by setting the node's provision state
using the ``active`` verb.
* ``manageable`` by setting the node's provision state using the ``manage``
verb
deploying
Nodes in ``deploying`` are being prepared to run a workload on them. This
consists of running a series of tasks, such as:
* Setting appropriate BIOS configurations
* Partitioning drives and laying down file systems.
* Creating any additional resources (node-specific network config, a config
drive partition, etc.) that may be required by additional subsystems.
wait call-back
Just like the ``deploying`` state, the nodes in ``wait call-back`` are being
deployed. The difference is that in ``wait call-back`` the conductor is
waiting for the ramdisk to boot or execute parts of the deployment which
need to run in-band on the node (for example, installing the bootloader, or
writing the image to the disk).
The deployment of a node in ``wait call-back`` can be interrupted by setting
the node's provision state using the ``deleted`` verb.
deploy failed
This is the state a node will move into when a deployment fails, for example
a timeout waiting for the ramdisk to PXE boot. From here the node can be
transitioned to:
* ``active`` (through ``deploying``) by setting the node's provision state
using either the ``active`` or ``rebuild`` verbs.
* ``available`` (through ``deleting`` and ``cleaning``) by setting the
node's provision state using the ``deleted`` verb.
active (stable state)
Nodes in ``active`` have a workload running on them. ironic may collect
out-of-band sensor information (including power state) on a regular basis.
Nodes in ``active`` can transition to:
* ``available`` (through ``deleting`` and ``cleaning``) by setting the node's
provision state using the ``deleted`` verb.
* ``active`` (through ``deploying``) by setting the node's provision state
using the ``rebuild`` verb.
deleting
Nodes in ``deleting`` state are being torn down from running an active
workload. In ``deleting``, ironic tears down and removes any configuration and
resources it added in ``deploying``.
error (stable state)
This is the state a node will move into when deleting an active deployment
fails. From ``error``, nodes can transition to:
* ``available`` (through ``deleting`` and ``cleaning``) by setting the node's
provision state using the ``deleted`` verb.
adopting
This state allows ironic to take over management of a baremetal node with an
existing workload on it. Ordinarily when a baremetal node is enrolled and
managed by ironic, it must transition through ``cleaning`` and ``deploying``
to reach ``active`` state. However, those baremetal nodes that have an
existing workload on them, do not need to be deployed or cleaned again, so
this transition allows these nodes to move directly from ``manageable`` to
``active``.