Docker developer DNS
This DNS purpose is to allow for developers to run their development
environments without the need to update their
/etc/hosts file. The additional
goal is to allow us to run a debug environment locally on the same domainname
as the 'live' environment. For now this DNS will be aimed at Linux users, over
time the goal is to provide a consistent platform for more operating systems.
This DNS will not try to create DNS entries for all running containers. You
must define what containers you want to be available in the DNS by using
To run this DNS server we need access to the docker socket so the DNS entries can be added dynamically.
$ docker run --name developer-dns \ -v /var/run/docker.sock:/var/run/docker.sock \ -p 127.0.0.1:53:53/udp \ blackikeeagle/developer-dns
You can find the basic systemd service file in contrib/systemd.
[Unit] Description=developer-dns After=network-online.target docker.service [Service] TimeoutStartSec=0 ExecStartPre=-/usr/bin/docker rm developer-dns ExecStart=/usr/bin/docker run --rm --name developer-dns \ -v /var/run/docker.sock:/var/run/docker.sock \ -p 127.0.0.1:53:53/udp \ -p 127.0.0.1:53:53 \ blackikeeagle/developer-dns ExecStartPost=-/usr/bin/docker pull blackikeeagle/developer-dns ExecStop=/usr/bin/docker stop developer-dns [Install] WantedBy=multi-user.target
To add support for changing networks you can add your dhcp received resolv.conf
to the container. To achieve this you must install openresolv and make use of
the resolvconf.conf file. In some
distributions you get a default configuration that stores files in tmp space
which can lead to some issues. So it's better to use a target location within
/etc as used in the file in contrib.
Add resolv.conf to the container:
Let a container have a DNS entry
You can use both
DOMAIN_NAME environment variables to get
an entry or comma seperated to add entries to the developer-dns.
single dns entry:
$ docker run --env VIRTUAL_HOST=test.dev nginx $ docker run --env DOMAIN_NAME=memcached.test.dev memcached
When dealing with webservers you might want to add more:
$ docker run --env VIRTUAL_HOST=mysite.dev,nl.mysite.dev,fr.mysite.dev,de.mysite.dev nginx $ docker run --env DOMAIN_NAME=mysite.dev,nl.mysite.dev,fr.mysite.dev,de.mysite.dev nginx
Personally I would recommend to use
VIRTUAL_HOST for http related entries and
DOMAIN_NAME for others. This way you can share you configuration with for
example OSX users using dinghy.
Resolve via developer-dns
You need to make sure your host can resolve the docker dns entries. This can be done in many ways, depending on the system you use.
On a system using resolvconf (eg. ubuntu) you can add this nameserver to the head.
# echo "nameserver 127.0.0.1" > /etc/resolvconf/resolv.conf.d/head
After making changes to resolvconf, you need to trigger a reload:
sudo resolvconf -u
On systems where openresolv is used you can use the file from
contrib and place it in
On systems using systemd resolved (eg. Ubuntu 17.04) you need to change:
# echo "DNS=127.0.0.1" >> /etc/systemd/resolved.conf
Reload resolved service:
$ sudo systemctl restart systemd-resolved.service
You could also add it manually to your network configuration gui like NetworkManager.