IPv6 in docker container and localhost problem

Twinsen · July 16, 2019, 10:09pm

Hello,

Docker is running on my Raspberry Pi. I have a problem with two environment variables ServerIPv6 and localhost dns.

Here is my Docker compose file:

version: "3"

More info at GitHub - pi-hole/docker-pi-hole: Pi-hole in a docker container and https://docs.pi-h$

services:
pihole:
container_name: pihole
image: pihole/pihole:latest
ports:
- "53:53/tcp"
- "53:53/udp"
- "67:67/udp"
- "80:80/tcp"
- "443:443/tcp"
environment:
ServerIP: 192.168.0.26
TZ: 'Europe/Berlin'
# WEBPASSWORD: 'set a secure password here or it will be random'
# Volumes store your data between container upgrades
volumes:
- '/home/pi/docker/pihole/etc-pihole/:/etc/pihole/'
- '/home/pi/docker/pihole/etc-dnsmasq.d/:/etc/dnsmasq.d/'
dns:
- 127.0.0.1
- 1.1.1.1
# Recommended but not required (DHCP needs NET_ADMIN)
# GitHub - pi-hole/docker-pi-hole: Pi-hole in a docker container
cap_add:
- NET_ADMIN
restart: unless-stopped

At first I run the compose file without the IPv6 ServerIP. After docker-compose up I got the following errors:

pihole | WARNING Misconfigured DNS in /etc/resolv.conf: Two DNS servers are recommended, 127.0.0.1 and any backup server
pihole | WARNING Misconfigured DNS in /etc/resolv.conf: Primary DNS should be 127.0.0.1 (found 127.0.0.11)
pihole |
pihole | nameserver 127.0.0.11

I do not understand where the IP address 127.0.0.11 comes from, but I could fix the problem by editing the resolve.conf file in the container.

sudo docker exec -i -t c4b0b6b8bf38 /bin/bash #by ID
sudo nano /etc/resolv.conf
pihole -g

With the instructions on the following internet page I have also enabled IPv6.

https://adminforge.de/dns/pi-hole-ipv6-und-die-fritzbox/

Upstream-DNS-Servers

My problem is that unfortunately all changes are gone after a restart and if I add the IPv6 server to my Docker compose file then I get a lot of error messages. If needed I can reproduce the error message. Please help me to fix the problem.

Best regards
Twinsen

mhoam · September 6, 2023, 10:48am

Hi, I have just come across your post when searching to resolve my own problems with IPv6 on Pihole in a Docker container.
These three posts may help you create an IPv6 enabled Docker Container for Pihole

github.com/moby/moby

Support IPv6

opened 03:28PM - 04 Feb 23 UTC

WilliamDEdwards

status/0-triage kind/feature area/networking area/networking/ipv6

### Description Maybe Docker/Moby should start supporting IPv6. And by 'supp…orting' I don't mean having to skim through GitHub comments and the Docker forum for hours to enable basic functionality. I tried to enable IPv6 for user-defined bridge networks. 1. To enable user-defined bridge networks, `default-address-pools` must be set. I set `default-address-pools`, causing Docker to not start anymore. There's [this months old issue](https://github.com/moby/moby/issues/44220#issuecomment-1379529812) that says an IPv4 address address pool should be before placed before an IPv6 address pool. Aside from the code smell that this bug brings, this requires me to set an IPv4 address pool. Why? 2. I attempted to remove `fixed-cidr-v6`, as I will only be using user-created networks, which caused Docker not to start anymore. I found [this forum post](https://forums.docker.com/t/assigning-default-ipv6-addresses/128665), which says: > The subnet specified in fixed-cidr-v6 defines what the docker0 network on the machine should look like. No more, no less. I still think this is poorly documented. And indeed, the documentation says that IPv6 cannot be disabled for the default bridge. However, nowhere does the [documentation](https://docs.docker.com/config/daemon/ipv6/) say that `fixed-cidr-v6` is the subnet used for the `docker0` bridge. 3. To add the IPv4 address pool (which should not be needed), I need to know what the IPv4 address pool is. This is not documented anywhere. I found [this almost 4 year old issue](https://github.com/docker/docs/issues/8663#issuecomment-956438889) requesting for this to be documented. 4. Finally having gotten Docker to stop complaining about missing or misordered settings, Docker crashed immediately on startup because it used all available RAM. I found [this almost 4 year old issue](https://github.com/moby/moby/issues/40275), which says that at least an /80 should be used. Makes sense, but why does Docker crash because of this 4! years after the bug report?!

These are not related to PiHole specifically but I have managed to get a PiHole container running with a IPv6 address. Still more work to do but these posts may help
cheers