This could be done using a system cron job which runs clace app update-metadata conf --promote container.idle_shutdown_secs=180 /myapp at every 6pm and then

This could be done using a system cron job which runs clace app update-metadata conf --promote container.idle_shutdown_secs=180 /myapp at every 6pm and then runs clace app update-metadata conf --promote container.idle_shutdown_secs=0 /myapp at 8am. idle_shutdown_secs being zero disables the shutdown. Using all as the last arg will update for all apps.