[ClusterLabs] Coming in Pacemaker 2.1.6: node attribute enhancements

[Ken Gaillot]

Hi all,

Node attributes will receive several enhacements in the Pacemaker 2.1.6
release, expected in late May. They are available now in the main
branch.

A longstanding request to support transient utilization attributes has
been implemented. Utilization attributes are used to assign resources
to nodes based on local metrics such as CPU cores, RAM size, etc.
Previously, these metrics could only be specified as permanent node
attributes. As of 2.1.6, they can be set as transient node attributes
as well (which last only until the cluster is restarted on the node).

Separately, attrd_updater will now support the -P/--pattern option to
modify all attributes whose name matches a given pattern. Previously,
only crm_attribute had the option.

attrd_updater and crm_attribute also both get a new -W/--wait option
that can be set to "no", "local", or "cluster" when changing an
attribute value.

With --wait=no (the default), the current behavior is preserved: the
command returns as soon as the request has been submitted to the
attribute manager.

With --wait=local, the tool will not return until the new value has
been set locally. That is, a query run on the same node would return
the new value.

With --wait=cluster, the tool will not return until the new value has
been set on all nodes. That is, a query on any node would return the
new value.

The --wait option will benefit scripts and resource agents that need
specific guarantees. The feature set can be compared against 3.17.4 to
determine support.
-- 
Ken Gaillot <kgaillot at redhat.com>