DNS resolution for Docker containers

[dbgokuu]

Hi, I've noticed something strange starting last Friday. My Plex installation all of a sudden stopped working, without me having changed any configuration whatsoever.

 

After some debugging, I came to the conclusion that the Plex container was not resolving plex.tv to the same IP address as the Unraid host:

 

On the host:

root@HomeServer:~# nslookup plex.tv
Server:         192.168.2.1
Address:        192.168.2.1#53

Non-authoritative answer:
Name:   plex.tv
Address: 34.243.94.189
Name:   plex.tv
Address: 34.241.88.179

 

On the containers (not using Plex container because it doesn't have nslookup, instead using a container with a similar network config):

root@ffebaaa320e3:/# nslookup plex.tv
Server:         127.0.0.11
Address:        127.0.0.11:53

Non-authoritative answer:
Name:   plex.tv
Address: 52.18.133.120
Name:   plex.tv
Address: 52.18.140.61

 

This is enough for Plex to get a certificate name error. 

Even though I worked around this by changing the container to use the host network (which made the name resolution work correctly), it is something I'd prefer to avoid. I'm also worrying that other containers may now be having other issues that stem from the same cause...

 

Any idea if/how it is possible to have the docker engine use the host's DNS resolution?