OpenStack Essex Design Summit

We've found a number of cases where the current handling of VM state makes some failure modes difficult to debug and confusing to the customers. For example a VM which takes a long time in building can be terminated, go to shutdown, and then jump back into life when the build completes. There are also a number of cases where the API allows calls that are inconsistent with the current state - which leads to non-deterministic behavior. We propose to better define and control the allowed state transitions, and introduce some specific failure states to make some failure mode more explicit.