my-runtipi/ddns-updater/config.json.local

{
    "settings": [
      {
        "provider": "cloudflare",
        "zone_identifier": "grab from zone overview page",
        "domain": "fqdn of dynamic hostname",
        "proxied": false,
        "ttl": 600,
        "token": "cloudflare DNS token",
        "ip_version": "ipv4",
        "ipv6_suffix": ""
      }
    ]
  }