Local DNS Server with Docker

This repository contains the necessary configuration to set up a local DNS server using Docker which offers name resolution of a local-only-domain rubel.app. The server is composed of two services: a resolver and an authoritative DNS server.

For more detailed instructions on setup, please refer to this post: https://dev.to/mich0w0h/setting-up-a-local-dns-service-with-docker-on-ubuntu-2204-290i

Services

the networking overview is here;

graph LR
  subgraph Docker
    subgraph "local-dns Network (192.168.1.0/24)"
      resolver[resolver: 192.168.1.101]
      authoritative[authoritative: 192.168.1.102]
    end
  end
  HostMachine[Host Machine]
  HostMachine -->|53/udp| resolver
  resolver -->|dns request| authoritative
  authoritative -->|dns response| resolver

Loading

Resolver

The resolver service is built from a Dockerfile located in the resolver directory. It uses Ubuntu 22.04 as a base image and installs Unbound, a lightweight DNS resolver. The configuration for Unbound is copied from resolver/unbound.conf into the container.

Authoritative

The authoritative service uses the coredns/coredns image from Docker Hub. It uses a configuration file located at authoritative/Corefile and a zone file located at authoritative/zone/rubel.app.db.

Network

The services are connected through a bridge network named internal-dns. The resolver service is assigned the IP address 192.168.1.101 and the authoritative service is assigned the IP address 192.168.1.102.

Running the Services

To start the services, use Docker Compose:

docker-compose -f compose.yml up

Note for Mapping Port 53 in Docker

Before running the services, ensure that port 53 is available on your host machine. On Ubuntu 22.04, systemd-resolved runs on port 53 by default. You will need to stop and disable systemd-resolved, or change its port before you can use port 53 for your Docker container.

Please note that these steps will change your DNS settings and disable systemd-resolved. Make sure you understand the implications of these changes before proceeding, or have a suitable replacement solution in place.

To stop and disable systemd-resolved, run:

sudo systemctl stop systemd-resolved
sudo systemctl disable systemd-resolved

Then, remove the symlink /etc/resolv.conf:

sudo rm /etc/resolv.conf

And create a new /etc/resolv.conf with a nameserver of your choice. For example, to use Google's DNS server:

echo "nameserver 8.8.8.8" | sudo tee /etc/resolv.conf