SOFTWARE-5448: Exit the supervisord init process if squid exits

[mwestphall]

A closed issue in supervisord recommends sending a SIGINT to supervisord at the end of a supervised process as a potential approach for exiting on the exit of the service: Supervisor/supervisor#712 Since supervisord is the init process of this container, the whole container will exit if the waited-on squid process ends in start-frontier-squid.sh

[matyasselmeci]

OK, interesting. Note that if squid (or $STARTSTOPSCRIPT) fails then this means supervisord won't restart it -- but we already throw away the exit code with the wait trick so I guess it would happen anyway.

[mwestphall]

OK, interesting. Note that if squid (or $STARTSTOPSCRIPT) fails then this means supervisord won't restart it -- but we already throw away the exit code with the wait trick so I guess it would happen anyway.

That might be an item to discuss - The ticket that suggests this change is somewhat ambiguous about when supervisord should shut down. Does it make sense for the whole container to exit if squid exits a single time (as in this change), or only after supervisord fails to recover the process?