Overview

Retiring nodes is a natural part of a server’s life cycle, for
instance when the end of the warranty is reached and the physical space
is needed for new deliveries to install replacement capacity.

However, depending on the type of the deployment, removing nodes from
service can be a full workflow by itself as it may include steps like
moving applications to other hosts, cleaning sensitive data from disks
or the BMC, or tracking the dismantling of servers from their racks.

Ironic provides some means to support such workflows by allowing to
tag nodes as retired which will prevent any further
scheduling of instances, but will still allow for other operations, such
as cleaning, to happen (this marks an important difference to nodes
which have the maintenance flag set).

How to use

When it is known that a node shall be retired, set the
retired flag on the node with:

baremetal node set --retired node-001

This can be done irrespective of the state the node is in, so in
particular while the node is active.

Optionally, a reason can be specified when a node is retired,
e.g.:

baremetal node set --retired node-001 \
  --retired-reason "End of warranty for delivery abc123"

Upon instance deletion, an active node with the
retired flag set will not move to available,
but to manageable. The node will hence not be eligible for
scheduling of new instances.

Equally, nodes with retired set to True cannot move from
manageable to available: the
provide verb is blocked. This is to prevent accidental
re-use of nodes tagged for removal from the fleet. In order to move
these nodes to available none the less, the
retired field needs to be removed first. This can be done
via:

baremetal node unset --retired node-001

In order to facilitate the identification of nodes marked for
retirement, e.g. by other teams, ironic also allows to list all nodes
which have the retired flag set:

baremetal node list --retired