Gracefully shutdown all servers on OS shutdown

[JasonHorkles]

When shutting down the OS, it would be cool if Pelican gracefully ran the shutdown action on all running servers before allowing the OS to continue

[Nazgile94]

but set timelimit to like 60 seconds, so if some container hangs it forces shutdown after XX seconds / minutes or let admin choose how long to wait for gracefully shutdown

[lancepioch]

The servers are running as docker containers. When you turn off your node, it sends the appropriate signals to each container. So this is already handled!