Table of Contents

Dynamic DNS (DDNS) is a method of automatically updating the DNS records of a domain name whenever the IP address changes. This is particularly useful for home networks or dynamic IP addresses provided by ISPs.

ddns-updater is a tool that supports many DNS providers, including desec.io, a free and open-source DNS service. We'll use Podman Quadlets to run ddns-updater as a systemd service, ensuring it starts automatically at boot and updates our DNS records whenever our IP address changes.

Kubefile

We have two containers in our pod, one for IPv4 and one for IPv6. The IPv4 container will update the DNS record for the IPv4 address, while the IPv6 container will do the same for the IPv6 address.

Depending on your provider the CONFIG environment variable must be different.

On the IPv6 container the HEALTH_SERVER_ADDRESS environment variable sets another port, because it is already used by the IPv4 container.

/opt/container/ddns-updater/kube.yaml:

---
apiVersion: v1
kind: Pod
metadata:
  labels:
    app: ddns-updater
    io.containers.autoupdate: registry
  name: ddns-updater
spec:
  containers:
    - image: docker.io/qmcgaw/ddns-updater:latest
      name: v4
      env:
      - name: LOG_LEVEL
        value: INFO
      - name: SERVER_ENABLED
        value: "false"
      - name: PERIOD
        value: 5m
      - name: CONFIG
        value: >
          {
            "settings": [
              {
                "provider": "desec",
                "domain": "ddns.example.com",
                "token": "",
                "ip_version": "ipv4",
                "ipv6_suffix": ""
              }
            ]
          }

    - image: docker.io/qmcgaw/ddns-updater:latest
      name: v6
      env:
      - name: LOG_LEVEL
        value: INFO
      - name: SERVER_ENABLED
        value: "false"
      - name: HEALTH_SERVER_ADDRESS
        value: "127.0.0.1:9998"
      - name: PERIOD
        value: 5m
      - name: CONFIG
        value: >
          {
            "settings": [
              {
                "provider": "desec",
                "domain": "ddns.example.com",
                "token": "",
                "ip_version": "ipv6",
                "ipv6_suffix": ""
              }
            ]
          }

Podman Quadlet

The quadlet file can be put under /etc/containers/sytemd/ddns-updater.kube for rootfull podman or <rootless user>/.config/containers/systemd/ddns-updater.kube for rootless podman.

[Install]
WantedBy=default.target

[Unit]

[Kube]
Yaml=/opt/container/ddns-updater/kube.yaml
Network=host

[Service]
# Restart service when sleep finishes
Restart=always
# Extend Timeout to allow time to pull the image
TimeoutStartSec=900

Reload systemd to recognize the new service:

# rootfull
sytemctl daemon-reload

# rootless
systemctl --user daemon-reload

Start the systemd service:

# rootfull
systemctl start ddns-updater

# rootless
systemctl --user start ddns-updater

View the status of the service:

# rootfull
systemctl status ddns-updater

# rootless
systemctl --user status ddns-updater

Show log of the service

podman logs ddns-updater-v4
podman logs ddns-updater-v6