Initial version

.gitignore

@@ -0,0 +1 @@
+hetzner-ddns.conf

README.md

@@ -0,0 +1,25 @@
+# Hetzner Dynamic DNS Updater
+
+This script finds this machine's hostname, public IPv4 and IPv6 addresses,
+then updates the corresponding DNS records on Hetzner.
+
+## Usage
+
+```text
+Usage:
+  hetzner-ddns.py [options]
+
+Options:
+  -h --help             Show this screen
+  --token=<str>         Hetzner API Token
+  --zone=<str>          Name of the DNS zone
+  --hostname=<std>      This machine's hostname
+  --ttl=<n>             Time-to-live in seconds
+  --v4-api=<url>        API that returns your public IPv4 address
+  --v6-api=<url>        API that returns your public IPv6 address
+  --retry-attempts=<n>  Retry N times if connection fails
+  --retry-delay=<s>     Wait S seconds between attempts
+  --config=<file>       Read options from configuration file
+  --disable-v4          Do not update IPv4 address
+  --disable-v6          Do not update IPv6 address
+```

hetzner-ddns.conf.example

@@ -0,0 +1,3 @@
+[example.com]
+token=ExAMpLEzLqUTQGBfzMQmxUWXkPL
+disable-ipv4=True

hetzner-ddns.py

@@ -0,0 +1,216 @@
+#!/usr/bin/env python3
+"""Hetzner Dynamic DNS Updater
+
+This script finds this machine's hostname, public IPv4 and IPv6 addresses,
+then updates the corresponding DNS records on Hetzner.
+
+Usage:
+  hetzner-ddns.py [options]
+
+Options:
+  -h --help             Show this screen
+  --token=<str>         Hetzner API Token
+  --zone=<str>          Name of the DNS zone
+  --hostname=<std>      This machine's hostname
+  --ttl=<n>             Time-to-live in seconds
+  --v4-api=<url>        API that returns your public IPv4 address
+  --v6-api=<url>        API that returns your public IPv6 address
+  --retry-attempts=<n>  Retry N times if connection fails
+  --retry-delay=<s>     Wait S seconds between attempts
+  --config=<file>       Read options from configuration file
+  --disable-v4          Do not update IPv4 address
+  --disable-v6          Do not update IPv6 address
+"""
+
+from docopt import docopt
+from time import sleep
+import json
+import os
+import requests
+import socket
+import sys
+import configparser
+
+
+args = docopt(__doc__)
+
+
+def merge_config_file():
+    global args
+    basepath = os.path.dirname(os.path.abspath(__file__))
+    candidate_config_files = [
+      args["--config"],
+      os.path.join(basepath, "hetzner-ddns.conf"),
+      "/etc/hetzner-ddns.conf",
+    ]
+
+    for filename in candidate_config_files:
+        if filename is None:
+            continue
+        if os.path.isfile(filename):
+            print("Reading options from %s" % filename)
+            config = configparser.ConfigParser()
+            config.read(filename)
+            
+            section_name = config.sections()[0]
+            print("    %-20s %s" % ("--zone", section_name))
+            args["--zone"] = section_name
+
+            section = config[section_name]
+            for key in args.keys():
+                if key[2:] in section:
+                    value = section[key[2:]]
+                    print("    %-20s %s" % (key, value))
+                    args[key] = value
+
+    return args
+
+def merge_defaults():
+    global args
+    default_args = {
+        "--ttl": 300,
+        "--v4-api": "https://v4.ident.me/",
+        "--v6-api": "https://v6.ident.me/",
+        "--retry-attempts": 12,
+        "--retry-delay": 5,
+        "--hostname": socket.gethostname(),
+    }
+
+    print("Applying default options:")
+    for (key, value) in default_args.items():
+        if args[key] is None:
+            print("    %-20s %s" % (key, value))
+            args[key] = value
+
+
+merge_config_file()
+
+if args["--token"] is None:
+    print("API token must be provided")
+    sys.exit(1)
+
+if args["--zone"] is None:
+    print("DNS zone must be provided")
+    sys.exit(1)
+
+merge_defaults()
+
+
+def get_addr(url,
+             retry=int(args["--retry-attempts"]),
+             delay=int(args["--retry-delay"])):
+    exception = None
+    for i in range(retry):
+        try:
+            import urllib
+            txt = urllib.request.urlopen(url).read()
+            return txt.decode("utf-8")
+        except Exception as e:
+            exception = e
+            print("    connection failed, retrying in %d seconds..." % delay)
+            sleep(delay)
+    raise(exception)
+
+
+def get_all_records(zone):
+    response = requests.get(url="https://dns.hetzner.com/api/v1/records",
+                            params={"zone_id": zone["id"]},
+                            headers={"Auth-API-Token": args["--token"]})
+    return response.json()["records"]
+
+
+def get_all_zones():
+    response = requests.get(url="https://dns.hetzner.com/api/v1/zones",
+                            headers={"Auth-API-Token": args["--token"]})
+    return response.json()["zones"]
+
+
+
+def find_record(zone, name, kind="AAAA"):
+    all_records = get_all_records(zone)
+    for r in all_records:
+        if r["type"] == kind and r["name"] == name:
+            return r
+    return None
+
+
+def find_zone(name):
+    all_zones = get_all_zones()
+    for z in all_zones:
+        if z["name"] == name:
+            return z
+    raise(Exception("Zone not found: %s" % name))
+
+
+def update_record(record):
+    response = requests.put(
+        url="https://dns.hetzner.com/api/v1/records/%s" % record["id"],
+        headers={
+            "Content-Type": "application/json",
+            "Auth-API-Token": args["--token"],
+        },
+        data=json.dumps(record)
+    )
+    response.raise_for_status()
+
+
+def create_record(record):
+    response = requests.post(
+        url="https://dns.hetzner.com/api/v1/records",
+        headers={
+            "Content-Type": "application/json",
+            "Auth-API-Token": args["--token"],
+        },
+        data=json.dumps(record)
+    )
+    response.raise_for_status()
+
+
+def main():
+    kinds = []
+
+    if not bool(args["--disable-v4"]):
+        kinds += ["A"]
+
+    if not bool(args["--disable-v6"]):
+        kinds += ["AAAA"]
+
+    print("Finding DNS zone...")
+    zone = find_zone(args["--zone"])
+
+    for kind in kinds:
+        if kind == "A":
+            print("Finding public IPv4 address...")
+            addr = get_addr(args["--v4-api"])
+            print("    %s" % addr)
+        else:
+            print("Finding public IPv6 address...")
+            addr = get_addr(args["--v6-api"])
+            print("    %s" % addr)
+
+        print("Finding existing %s record..." % kind)
+        rec = find_record(zone=zone,
+                          kind=kind,
+                          name=args["--hostname"])
+        
+        if rec is None:
+            print("    not found")
+            print("Creating new %s record..." % kind)
+            create_record({
+                "value": addr,
+                "type": kind,
+                "name": args["--hostname"],
+                "zone_id": args["--zone"],
+                "ttl": args["--ttl"],
+            })
+            print("    done")
+        else:
+            print("    found")
+            print("Updating existing %s record..." % kind)
+            rec["value"] = addr
+            rec["ttl"] = args["--ttl"]
+            update_record(rec)
+            print("    done")
+
+
+main()