After update: ERROR: ServerIPv6 Environment variable (fd01::XXXX:XXXX:XXXX:XXXX) doesn't appear to be a valid IPv6 address

[tomut]

I just updated my Pi-hole docker container and noticed that it didn't start back up. The logs show this over and over again:

pihole    | [s6-init] making user provided files available at /var/run/s6/etc...exited 0.
pihole    | [s6-init] ensuring user provided files have correct perms...exited 0.
pihole    | [fix-attrs.d] applying ownership & permissions fixes...
pihole    | [fix-attrs.d] 01-resolver-resolv: applying... 
pihole    | [fix-attrs.d] 01-resolver-resolv: exited 0.
pihole    | [fix-attrs.d] done.
pihole    | [cont-init.d] executing container initialization scripts...
pihole    | [cont-init.d] 20-start.sh: executing... 
pihole    |  ::: Starting docker specific checks & setup for docker pihole/pihole
pihole    | RTNETLINK answers: Network is unreachable
pihole    | ERROR: ServerIPv6 Environment variable (fd01::XXXX:XXXX:XXXX:XXXX) doesn't appear to be a valid IPv6 address
pihole    |   TIP: If your server is not IPv6 enabled just remove '-e ServerIPv6' from your docker container
pihole    | [cont-init.d] 20-start.sh: exited 1.
pihole    | [cont-finish.d] executing container finish scripts...
pihole    | [cont-finish.d] done.
pihole    | [s6-finish] waiting for services.
pihole    | [s6-finish] sending all processes the TERM signal.
pihole    | [s6-finish] sending all processes the KILL signal and exiting.

I'm not sure why it doesn't like this IPv6 address. It had worked just fine for a long, long time, across many updates. I checked the ethernet interface and it definitely has this IPv6 address. I tried expanding the "::" to 0s but it still fails. Only way to get it working was to uncomment the ServerIPv6, but I need IPv6 enabled.

Since this has worked just fine I suspect there's a glitch with this latest release. Short of reverting back to an older image, does anyone know if there's a way to fix this?

[Bucking_Horn]

Please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:

pihole -d

or do it through the Web interface:

Tools > Generate Debug Log

[tomut]

https://tricorder.pi-hole.net/N33CQYR6/

[Bucking_Horn]

You are running Pi-hole in a Docker container.
Note that by default, Docker is IPv4 only, so a message about IPv6 network issues is somewhat expected at Docker startup (see also this similar topic back from 2018).

Your debug log suggests that Pi-hole is handling DNS requests from IPv4 clients as expected, so I am not sure what your issue would be.

Apart from those log messages, do you observe any DNS related irregularities?

[tomut]

Yes I am using docker. Ok, it looks like I don't actually need ipv6 on those vlans anymore. I was just thrown off because I still hand out the fd01: ipv6 addresses and this had been seemingly working until I updated the container recently. So I'm guessing it was never actually working and setting the ServerIPv6 variable was just silently ignored then? Anyway, thanks for explaining, I wasn't aware that docker doesn't enable ipv6 by default.