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

[Raphaël Badin]

[...]
>> (Aside: once a node has been deployed, MAAS can no longer have a desired
>> power state to converge on. The node belongs to the user at that point,
>> and he/she has the freedom to turn it off and on as needed, and he/she
>> can do that by mechanisms other than by MAAS.)
>
> Massively disagree.
>
> We need to make a stand here and insist that MAAS controls all aspects of the
> Node, including its power.  MAAS must always know what state the node needs to
> be in, unless it is broken.
>
> J
>

I think there is a middle ground here: it's true that MAAS should 
consider it is in control of the nodes; controlling (and monitoring) the 
power state is certainly part of it.  But as Gavin pointed out, once a 
node is deployed, it's out of the question to consider it an *error* (as 
in, something so bad MAAS will transition a node to an error state) if 
the actual power state is different from the expected power state.

That's precisely why the "error state" attached to deployed ("needs 
attention") in [1] it not a new state but a flag.

[1] 
https://docs.google.com/a/canonical.com/drawings/d/1cyxOShj5knaHwqtR45id9paIBF_j3NhgLpJVnx5KeEM/edit