Allow foreground execution for s6 style service

[diginc]

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Simple request: since backgrounding/daemonizing is the default of pihole-FTL, please provide a -f argument to run it in the foreground to provide some more versatility with other supervisor style service managers like s6.

I just converted the pi-hole docker image to use s6-overlay, all my other services for the docker-pi-hole container have a option to run them int he foreground so that s6-supervisor can properly watch the long running process (also intake logs) and restart it if something goes wrong.

More details on s6 services: http://www.skarnet.org/software/s6/servicedir.html see the bullet points, the 5th in particular:

execute into the long-lived process that is to be supervised by s6-supervise, i.e. the real foo daemon. That process must not "background itself": being run by a supervision tree already makes it a "background" task.

s6 will just restart a service over and over when the process goes into background mode (learned this with php-fpm) since it is a supervisor style service manager, the exit of the run script means the service stopped in s6's mind and it triggers another run unless it was just told to stop the service.

I can work around this for now with something silly like while pgrep pihole-FTL ; do sleep 5 ; done at the end of my s6 service run script, so no rush.

[dschaper]

So you need a no-daemon mode to get things working correctly? I could see this helping out with debugging and possibly with some of the test in the Travis build matrix to smoke test builds in the x86 platform.

[technicalpyro]

starting FTL with the command pihole-FTL debug should prevent it from going into daemon mode

EDIT taken from https://github.com/pi-hole/FTL#command-line-arguments

[diginc]

ah yup pihole-FTL debug is what I need, thanks. Next time I'll RTFM. I tried pihole-FTL -h but there was no help there :(

[DL6ER]

Although you have been able to achieve what you need using debug this also enabled the ultra-verbose mode (your log file will grow quickly). I'll reopen this issue to remind myself to implement

• a no-daemon, -f, and
• a help, -h flag