graceful nginx shutdown prehook (#3373)
graceful nginx shutdown prehook (#3373)

https://pracucci.com/graceful-shutdown-of-kubernetes-pods.html
zooniverse/Panoptes,camallen/Panoptes,zooniverse/Panoptes,camallen/Panoptes,zooniverse/Panoptes,camallen/Panoptes,zooniverse/Panoptes,camallen/Panoptes