Domain with invalid DT

[buzztroll]

When a user launches a domain with a DT name that is not in DTRS, no error is ever reported to the user.

[priteau]

This is not the fault of the DTRS itself: when a non-existing DT is looked up, an exception is triggered. This exception is caught by the provisioner which marks the launch as failed. The error is documented in the state_desc field of the instance object:

state: 900-FAILED
state_desc: 'DTRS_LOOKUP_FAILED Unknown deployable type name: sleepers'

I don't know how we should fix this bug. The provision() call is asynchronous, which means EPUM would have to check the status of a launch for this kind of error.

Also, provisioning happens when the decision engine runs, asynchronously from add_domain/reconfigure_domain.

What method should we use to return an error to the user?