Dynamic DNS with DDClient, Cloudflare, and Docker

#tutorial
2020/08/20

What's Dynamic DNS?

Dynamic DNS is a mechanism to automatically update DNS records with the location of a device or system. Systems that have "floating" IP addresses (such as most home consumer internet connections) need Dynamic DNS to have a constantly addressable domain name.

Configuration Steps

  1. Get your Cloudflare Global API Key

    1. Head to https://cloudflare.com and log in
    2. In the profile drop-down in the top-right, select My Profile
    3. From the tabs at the top, select API Tokens
    4. Under API Keys, next to Global API Key, select View
    5. If required, re-enter your password / solve the CAPTCHA
    6. Copy down the Global API Key shown

  2. On your server, get your user's UID and GID

    1. You can get your UID with id -u username
    2. You can get your GID with id -g username

  3. On your server, create a new ddclient folder

    • The folder will be copied wholesale into the container, so you don't want too much garbage in it

  4. In this folder, create a new ddclient.conf file, with the following contents:

    ddclient.conf
    use=web, web=ipinfo.io/ip
protocol=cloudflare, \
zone=<your zone>, \
login=<your cloudflare login email>, \
password=<your global API key> \
<DNS record to update>

    So, for example:

    Example ddclient.conf
    use=web, web=ipinfo.io/ip
protocol=cloudflare, \
zone=example.com, \
login=me@example.com, \
password=e3199589b1476ebca5c8547f780da80843431 \
server.example.com

    NOTE: There is no comma after the password entry!

    WARNING: The Global API key is essentially the same as your cloudflare password: Make sure you don't accidentally check it into source control!

  5. Also in the folder, create a new docker-compose.yml file, with the following contents:

    docker-compose.yml
    version: "3.7"
services:
  ddclient:
    image: linuxserver/ddclient
    container_name: ddclient
    environment:
      - PUID=<Your user's UID>
      - PGID=<Your user's GID>
      - TZ=<Your timezone>
    volumes:
      - .:/config
    restart: unless-stopped

    So, for example:

    Example ddclient.conf
    version: "3.7"
services:
  ddclient:
    image: linuxserver/ddclient
    container_name: ddclient
    environment:
      - PUID=1001
      - PGID=1001
      - TZ=Europe/London
    volumes:
      - .:/config
    restart: unless-stopped

  6. Start the ddclient service

    1. In the folder, run docker-compose up -d
      • (You may need to run sudo beforehand.)

That's it! You should now have a functional ddclient instance creating and updating a DNS A record in cloudflare DNS. The restart setting will ensure the container restarts if the hosting server restarts.

If the record doesn't seem to be updating, you can check the logs of the running container with docker logs ddclient.