anujdatar/cloudflare-ddns

Cloudflare DynDNS Updater in a docker

https://github.com/anujdatar/cloudflare-ddns-docker

Update IP on Cloudflare periodically. Works with docker secrets. Built for amd64, arm64 and armv7, but only tested on amd64, and arm64.

Now using alpine:latest image for a small footprint. I know alpine:3.13 had an issue with armv7. Have not tested latest image on armv7. If you have issues, let me know. Will revert to alpine:3.12.

Now supports IPv6 or AAAA record updates too, but this needs additional settings. Please read section below.

Container packages available from Docker Hub and Github Container Registry (ghcr.io)

• Docker Hub Image: anujdatar/cloudflare-ddns
• GHCR Image: ghcr.io/anujdatar/cloudflare-ddns

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Parameters / Environment Variables

Multiple subdomains

In order to update multiple DNS records with your dynamic IP, please create CNAME records and point them to the A or AAAA record used in this container.

---

USAGE

Docker cli

Recommended method is using a scoped API token (zone). Limits the privileges given to the container.

bash
docker run \
    -e API_KEY="<your-scoped-api-token>" \
    -e ZONE="<your-dns-zone>"  \
    -e SUBDOMAIN="<subdomain-a-record>" \
    -e RECORD_TYPE=A \
    --name cloudflare-ddns \
    anujdatar/cloudflare-ddns

Using a global API token

bash
docker run \
    -e METHOD=GLOBAL \
    -e API_KEY="<your-global-api-token>" \
    -e EMAIL="email@example.com" \
    -e ZONE="<your-dns-zone>"  \
    -e SUBDOMAIN="<subdomain-a-record>" \
    --name cloudflare-ddns \
    anujdatar/cloudflare-ddns

docker-compose

yaml
version: "3"
services:
  cloudflare-ddns:
    image: anujdatar/cloudflare-ddns
    container_name: cloudflare-ddns
    restart: unless-stopped
    environment:
      - API_KEY="<your-scoped-api-token>"
      - ZONE="<your-dns-zone>"
      - SUBDOMAIN="<subdomain-a-record>"
      - FREQUENCY=1  # OPTIONAL, default is 5

using docker-compose and docker secrets

In case you plan to commit your docker-compose files to repos and wish to keep tokens/domains secure

yaml
version: "3"
services:
  cloudflare-ddns:
    image: anujdatar/cloudflare-ddns
    container_name: cloudflare-ddns
    restart: unless-stopped
    environment:
      - METHOD=GLOBAL
      - API_KEY_FILE=/run/secrets/api_key
      - EMAIL=/run/secrets/email
      - ZONE=/run/secrets/zone
    secrets:
      - api_key
      - email
      - zone

secrets:
  api__key:
    external: true
  email:
    file: ./email.txt
  zone:
  	file: ./zone.txt

External secrets can be Docker Secrets created using the docker secret create command

bash
echo <your-scoped-api-token> | docker secret create api_key -

Your secret files should just be plain text strings containing zone/subdomain/email/token etc.

email.txt

txt
email@example.com

zone.txt

txt
example.com

---

Using IPv6

Docker by default only has IPv4 enabled. So containers can only access the web through IPv4. IPv6 traffic is not available by default. There are a few ways you can enable this, these are the quickest I found. I will link official docs where possible.

First you will have to allow IPv6 internet access to the docker subnet on your Host machine. Assuming the private Docker subnet we assign in the steps below is fd00::/64. You can use a different subnet if you wish. Or you may need to use a different subnet if you have multiple docker networks with IPv6 enabled.

bash
ip6tables -t nat -A POSTROUTING -s fd00::/64 -j MASQUERADE

This setting is not persistent, and will not survive a reboot. To make it persistent

bash
# install iptables-persistent and netfilter-persistent
sudo apt-get install iptables-persistent netfilter-persistent

# save you rules
sudo iptables-save > /etc/iptables/rules.v4
sudo ip6tables-save > /etc/iptables/rules.v6

# restart services
sudo systemctl restart netfilter-persistent

# if you need to restore backed-up rules
sudo iptables-restore < /etc/iptables/rules.v4
sudo ip6tables-restore < /etc/iptables/rules.v6

For more information on persistent rules or iptables on RPM based systems, refer to https://askubuntu.com/questions/***/iptables-reload-restart-on-ubuntu/***#*** and 2

For more on IPv6 and docker you can check out this medium article. I do not expose individual docker containers to internet via IPv6 directly, but the article goes over ways to do this. If you need it.

1. Enable IPv6 on the default bridge network

Source: https://docs.docker.com/config/daemon/ipv6/

1. Edit etc/docker/daemon.json and add the following

   json
    {
      "ipv6": true,
      "fixed-cidr-v6": "fd00::/64"
    }
   

2. Reload the docker config file

   sh
   $ systemctl reload docker
   # or restart the docker service
   $ systemctl restart docker
   

3. You can now start any container connected to the default bridge. You should have IPv6 access. To connect a docker-compose container to default bridge, add network_mode: bridge option to the service.

2. Create a new persistent network with IPv6 access

In case you want to keep your networks separate.

bash
docker network create --subnet=172.16.2.0/24 --gateway=172.16.2.1 --ipv6 --subnet=fd00::/64 ipv6bridge

You can now connect your container to this network using --network ipv6bridge. Or in your docker-compose.yml file using

yaml
services:
  your-service-name:
    image: xyz
    other-options: options
    networks:
      - my-net

networks:
  my-net:
    external:
      name: ipv6bridge

or

yaml
services:
  your-service-name:
    image: xyz
    other-options: options

networks:
  default:
    external:
      name: ipv6bridge

3. Define the network in your docker-compose file

This will be a disposable network, and will be removed when you stop your application. This example changes the default network of all the services in the application. You can create a named network and assign it to services individually as well.

Source: https://docs.docker.com/compose/networking/

yaml
services:
  your-service-name:
    image: xyz
    other-options: options

networks:
  default:
    driver: bridge
    enable_ipv6: true
    ipam:
      driver: default
      config:
        - subnet: fd00::/64

---

Creating a Scoped Token on Cloudflare

To create a scoped token with only DNS privileges, go to https://dash.cloudflare.com/profile/api-tokens and create a CUSTOM TOKEN with the following permissions

1. Zone - Zone Settings - Read
2. Zone - Zone - Read
3. Zone - DNS - Edit

You may choose to include all zones on one specific zone based on your preferences.

IPv6 with ufw

UFW seems to have an issue properly routing ipv6 traffic to docker networks. This is what worked for me after a lot of trial and error. Since most of it similar to the section above, I'll try keep it brief.

1. Enable IPv6 on the default bridge network

Assuming your default docker network interface is docker0 (check using ip a), and you're still using the same fd00::/64 subnet.

1. Edit etc/docker/daemon.json and add the following

   json
    {
      "ipv6": true,
      "fixed-cidr-v6": "fd00::/64"
    }
   

2. Reload the docker config file

   bash
   systemctl reload docker
   # or restart the docker service
   systemctl restart docker
   

3. Update ufw and iptables settings

   bash
   sudo ufw route allow in on docker0
   sudo ip6tables -t nat -A POSTROUTING -s fd00::/64 -j MASQUERADE
   sudo iptables -t mangle -A FORWARD -i docker0 -o end0 -j ACCEPT
   sudo iptables -t mangle -A FORWARD -i end0 -o docker0 -j ACCEPT
   
   # install iptables-persistent and netfilter-persistent
   sudo apt-get install iptables-persistent netfilter-persistent
   

2. Create a new persistent network with IPv6 access

In case you want to keep your networks separate. Assuming you're still using the same fd00::/64 subnet. To keep things repeatable you might also want to assign a name to your new network interface instead of some default like br-451d9eb3tes8. I'll call it ipv6-bridge.

NOTE: network interface name is different from the docker network name. you can check the name after you've created the network using ip a

bash
docker network create --subnet=172.16.2.0/24 --gateway=172.16.2.1 --ipv6 --subnet=fd00::/64 --opt com.docker.network.bridge.name=ipv6-bridge ipv6bridge

Update ufw and iptables settings

bash
sudo ufw route allow in on ipv6-bridge
sudo ip6tables -t nat -A POSTROUTING -s fd00::/64 -j MASQUERADE
sudo iptables -t mangle -A FORWARD -i ipv6-bridge -o end0 -j ACCEPT
sudo iptables -t mangle -A FORWARD -i end0 -o ipv6-bridge -j ACCEPT

# install iptables-persistent and netfilter-persistent
sudo apt-get install iptables-persistent netfilter-persistent

You can now connect your container to this network using --network ipv6bridge. Or in your docker-compose.yml file using

yaml
services:
  your-service-name:
    image: xyz
    other-options: options

networks:
  default:
    external:
      name: ipv6bridge

3. Define the network in your docker-compose file

This will be a disposable network, and will be removed when you stop your application.

Again, assuming you use the subnet fd00::/64 and use ipv6-bridge for the interface name.

Add ufw and iptables rules

bash
sudo ufw route allow in on ipv6-bridge
sudo ip6tables -t nat -A POSTROUTING -s fd00::/64 -j MASQUERADE
sudo iptables -t mangle -A FORWARD -i ipv6-bridge -o end0 -j ACCEPT
sudo iptables -t mangle -A FORWARD -i end0 -o ipv6-bridge -j ACCEPT

# install iptables-persistent and netfilter-persistent
sudo apt-get install iptables-persistent netfilter-persistent

Source: https://docs.docker.com/compose/networking/

yaml
services:
  your-service-name:
    image: xyz
    other-options: options

networks:
  default:
    driver: bridge
    enable_ipv6: true
    ipam:
      driver: default
      config:
        - subnet: fd00::/64
    driver_opts:
      com.docker.network.bridge.name: ipv6-bridge