[Maas-devel] RFC: "Serialising" power actions

[Mark Shuttleworth]

In response to this thread:

 * dropping and interpolating are both fraught with problems

Therefor:

 * please implement a queue
 * please ensure that there is an externally imposed timeout on every
action (so the queue never gets fully blocked even if one gets stuck)
 * think carefully about how to handle a failure - does that invalidate
the node, or do we initiate an attempt to reset the BMC and re-establish
control
 * provide feedback on the queue on commands, e.g.

   $ maas power-off node1
   Queue of power actions on node1:
   * reboot (for admin) in progress
   * reboot (for admin)
   * pxe-boot (for fred)
   then will power-off for you.


   $ maas power-off node2
   Powering off node2 for you now.
 

While that may seem pedantic, it's most understandable to the user
because they don't have to know what MAAS is doing or why; MAAS is just
doing what it has been told, and they can talk to the user in question
if it's been told something silly.

Mark

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