During the implementation of blueprint request-filter-image-types,
I left a FIXME to follow-up and add an ability for an operator to
configure compute nodes to not expose image formats that they *can*
support, for situations where they may not be desired. Consider a
remote compute node which *can* support raw images, but for which
you want to require that the user use qcow2 for transfer efficiency.
This adds a new compute-level config option which allows excluding
image types, which will be filtered out of the traits list in a
general way, to avoid having to honor the list in each driver.
Change-Id: Iabe6246dba212b1a287a82cc0cf16e2e8c8a24b8
cf0e519a0e