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Hi folks.

Recently I got several requests to implement API aborting introspection 
in discoverd. This is useful mostly when debugging, when you know that 
introspection has failed, and you want to stop it right now. I've put a 
blueprint 
https://blueprints.launchpad.net/ironic-discoverd/+spec/abort-introspection 
to track it.

Such API would cause discoverd to set error state for the node 
immediately and issue a power off request for it. The technical side is 
not a big deal.

What I'm worried about is whether we want to introduce such a feature at 
all. Some Ironic processes (deploy, in-band cleaning) are async as well, 
they also may hang, and IIUC we don't have means of aborting them. Does 
debugging justify introducing new API?

This looks somewhat similar to our discussion about breaking locks in 
Ironic: it might be useful, but it's an API which we'll support and 
which can be easily misused.

But with introspection the only case where lack of this feature can't be 
easily worked around is when people want to recreate a node. I've been 
arguing for some time that recreating a node is not a good way to solve 
problems. In other cases one can just power off the node via Ironic API 
and restart the introspection again afterwards.

What do you think?

Cheers,
Dmitry