Update docker-compose.yml

[thexavier666]

Removed DNS settings which pointed to 1.1.1.1, since direct connections to 1.1.1.1 bypasses DoH.
Queries should instead go through cloudflared only, which is 172.20.0.3 in this example.
I've tested it in my system using https://dnsleaktest.com.

[ilopmar]

Without this line I see the following errors when pihole container starts:

...
pihole         |   Checking if custom gravity.db is set in /etc/pihole/pihole-FTL.conf
pihole         |   Skipping Gravity Database Update.
pihole         | 
pihole         | s6-rc: info: service legacy-services successfully started
pihole         | fatal: unable to access 'https://github.com/pi-hole/pi-hole/': Could not resolve host: github.com
pihole         | fatal: unable to access 'https://github.com/pi-hole/AdminLTE/': Could not resolve host: github.com
pihole         | fatal: unable to access 'https://github.com/pi-hole/FTL/': Could not resolve host: github.com
pihole         |   Pi-hole version is v5.15.3 (Latest: null)
pihole         |   AdminLTE version is v5.18.3 (Latest: null)
pihole         |   FTL version is v5.20.1 (Latest: null)
pihole         |   Container tag is: 2023.01.10

Then if I docker exec into the pihole container a ping command fails to resolve the name:

$ docker exec -it pihole bash
root@pihole:/# ping google.com
ping: google.com: Temporary failure in name resolution

Adding back that 1.1.1.1 dns entry the startup looks good:

...
pihole         | s6-rc: info: service legacy-services: starting
pihole         |   Checking if custom gravity.db is set in /etc/pihole/pihole-FTL.conf
pihole         |   Skipping Gravity Database Update.
pihole         | 
pihole         | s6-rc: info: service legacy-services successfully started
pihole         |   Pi-hole version is v5.15.3 (Latest: null)
pihole         |   AdminLTE version is v5.18.3 (Latest: null)
pihole         |   FTL version is v5.20.1 (Latest: null)
pihole         |   Container tag is: 2023.01.10

Now the ping works:

$ docker exec -it pihole bash
root@pihole:/# ping google.com
PING google.com (142.250.200.78) 56(84) bytes of data.
64 bytes from mad07s24-in-f14.1e100.net (142.250.200.78): icmp_seq=1 ttl=249 time=3.66 ms
64 bytes from mad07s24-in-f14.1e100.net (142.250.200.78): icmp_seq=2 ttl=249 time=4.13 ms
...