I have put up a review <https://reviews.apache.org/r/26391/> which removes the special casing and handling of the ‘rack’ constraint. This is a breaking change because Aurora will no longer inject a rack constraint of 1 if a job omits a rack constraint value. However this means that Aurora will be able to schedule jobs on to slaves which don’t have the ‘rack’ attribute and slaves that want to accept tasks from Aurora don’t need to have the ‘rack’ attribute set.
Before the next release of Aurora (0.6.0) you should check if you are relying on the injected value for scheduling decisions and if so explicitly encode a rack limit of 1 in the job's aurora config. -- Zameer Manji
