How to restart a specific openstack-service installed using devstack?
When ./stack.sh completes, openstack is ostensibly running.
as your stack user, you can then issue this command:
screen -dr
this should open up a screen session with windows for each of the services. the services are running from those screen terminal sessions or ptys.
you can simply kill the process and restart it from those ptys.
of course standard logical order of operations apply. if mysql is dead, nova-api won't start up very well. same goes for keystone being off. so, pay attention to dependencies.
if you are unsure of how to execute the services in the terminals, first do a ps auxww | grep service or something to that affect. That should provide some insight on how to run the binaries again.
Good luck.