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

[Julian Edwards]

On Wednesday 17 Sep 2014 09:12:19 Raphaël Badin wrote:
> [...]
> 
> >> (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.

No, I disagree.  It's an error because MAAS is in control and expects it to  
be in a particular state.

You cannot have a half way house, either MAAS is managing it or it is not.  
MAAS owns the network.

> 
> 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/1cyxOShj5knaHwqtR45id9paI
> BF_j3NhgLpJVnx5KeEM/edit