dyndns

Installs a shell script and cron job that tracks the host's public IP and updates Hetzner DNS A records whenever it changes.

Requirements

• cron and curl (installed automatically)
• Hetzner DNS API token(s)

Variables

Variable	Default	Description
dyndns_path	/dyndns	Base directory for per-zone configuration. See Usage for the expected layout.
dyndns_interval	*/5	Cron minute expression controlling how often the IP check runs.
dyndns_uninstall	false	Removes the cron job and the dyndns script.
dyndns_purge	false	Also removes dyndns_path. Requires dyndns_uninstall: true. Irreversible.

Usage

Directory layout

The script reads zone configuration from subdirectories of dyndns_path. Each subdirectory name is a DNS zone ID, and must contain:

• .token — Hetzner DNS API token for that zone
• One file per record name to update (filename = record name, content ignored)

/dyndns/
└── <zone-id>/
    ├── .token
    ├── home          # updates home.<zone>
    └── vpn           # updates vpn.<zone>

Populate these files before or after running the role. The script skips any zone directory that is missing a .token file.

Custom interval

dyndns_interval: "*/10" # check every 10 minutes

Custom base path

dyndns_path: /etc/dyndns

Managing individual records

Use tasks/record.yml as a standalone include to add or remove a single record without re-running the full role:

- ansible.builtin.include_role:
    name: dyndns
    tasks_from: record
  vars:
    dyndns_zone: "<zone-id>"
    dyndns_record: "home"
    dyndns_record_state: present # or absent

The task requires the zone directory to already exist (i.e. the role has been run for that zone). dyndns_record_state defaults to present if omitted.

Uninstall

To remove the cron job and the script:

dyndns_uninstall: true

To also remove the configuration directory (irreversible):

dyndns_uninstall: true
dyndns_purge: true

Notes

• The script installs to /usr/local/bin/dyndns and runs as root.
• Public IP is resolved via ipinfo.io, ipecho.net, and checkip.amazonaws.com in order; the first successful response wins.
• Updates are skipped when the IP has not changed since the last run (tracked in dyndns_path/.last_ip).
• All output is appended to /var/log/dyndns.log.