Wait after restarting FTL before trying to check version

[DL6ER]

What does this implement/fix?

Prevent errors like seen in #5608 (comment) when Pi-hole uses itself as nameserver:

 Please note that changing branches severely alters your Pi-hole subsystems
  Features that work on the master branch, may not on a development branch
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  [✓] Branch fix/ede_neterr exists
  [i] Switching to branch: "fix/ede_neterr" from "fix/ede_neterr"
  [✓] Downloading and Installing FTL
  [✓] Restarting pihole-FTL service...
  [✓] Enabling pihole-FTL service to start on reboot...
fatal: unable to access 'https://github.com/pi-hole/pi-hole/': Could not resolve host: github.com
fatal: unable to access 'https://github.com/pi-hole/web/': Could not resolve host: github.com
fatal: unable to access 'https://github.com/pi-hole/FTL/': Could not resolve host: github.com

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Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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[yubiuser]

I agree with rdwebdesign. We should be not have an infinite loop that depends on outside conditions (network availability). I think we should have a counter and exit the loop after e.g. 10 seconds and ask users to manually run the update command afterwards.

[PromoFaux]

I am not sure where my mind was when I first responded to RD's comment. Reading over the code again, actually it probably is a fair shout that we timeout after x seconds (the user could always ctrl+c, but that is not overly friendly

[DL6ER]

The script is constantly adding . to the output to show it's still alive. Waiting "forever" seems fine to me as the updater has no way to finish properly when there in no way to contact GitHub.

The suggested alternative is erroring out with no option for the user to wait longer if 10 seconds isn't enough to restart FTL on their RPi Zero with 100,000 queries to import from the database. Sure, the timeout could be 60 seconds but my opinion is that waiting "forever" and constantly showing that the script is still alive is the proper way to do this

[yubiuser]

I know we had this before, but maybe the answer changed in-between: do we have any signal that would signal FTL's readiness to accept DNS queries (e.g. a second pid file)?

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This PR is not about FTL only. The cat might have unplugged the cable just at the right moment - FTL might be ready for a long time, but there would be no network connectivity.

[DL6ER]

We could dig pi.hole or whatever always resolves without being forwarded.

I hear you and you are right, it's about more than FTL alone. However, without connectivity, there is no (simple) way the updater can exit gracefully.

[yubiuser]

dig pi.hole @localhost could work. But this tells us only that FTL is ready, but has no meaning for systems that don't use FTL for their host's DNS resolution.

[rdwebdesign]

Sure, the timeout could be 60 seconds but my opinion is that waiting "forever" and constantly showing that the script is still alive is the proper way to do this

Should we add here a text explaining FTL can take some time to restart and the process can loop forever without a connection? ("this can take several seconds")

Should we add "Press CTRL+C to exit"?
Or something like a simplified version of this spinner?