Docker cannot resolve DNS on private network [closed]

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Docker populates /etc/resolv.conf by copying the host’s /etc/resolv.conf, and filtering out any local nameservers such as 127.0.1.1. If there are no nameservers left after that, Docker will add Google’s public DNS servers (8.8.8.8 and 8.8.4.4).

According to the Docker documentation:

Note: If you need access to a host’s localhost resolver, you must modify your DNS service on the host to listen on a non-localhost address that is reachable from within the container.

The DNS service on the host is dnsmasq, so if you make dnsmasq listen on your docker IP and add that to resolv.conf, docker will configure the containers to use that as the nameserver.

1 . Create/edit /etc/dnsmasq.conf† and add these lines:

interface=lo
interface=docker0

2 . Find your docker IP (in this case, 172.17.0.1):

root@host:~# ifconfig | grep -A2 docker0
docker0   Link encap:Ethernet  HWaddr 02:42:bb:b4:4a:50  
          inet addr:172.17.0.1  Bcast:0.0.0.0  Mask:255.255.0.0

3 . Create/edit /etc/resolvconf/resolv.conf.d/tail and add this line:

nameserver 172.17.0.1

4 . Restart networking, update resolv.conf, restart docker:

sudo service network-manager restart
sudo resolvconf -u
sudo service docker restart

Your containers will now be able to resolve DNS from whatever DNS servers the host machine is using.

† The path may be /etc/dnsmasq.conf, /etc/dnsmasq.conf.d/docker.conf, /etc/NetworkManager/dnsmasq.conf, or /etc/NetworkManager/dnsmasq.d/docker.conf depending on your system and personal preferences.

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