Use zone ID instead of name

Makefile

@@ -2,6 +2,7 @@ install:
 	cp hetzner-ddns.py /usr/local/bin
 	cp etc/hetzner-ddns.conf.example /etc
 	cp etc/systemd/hetzner-ddns.service /etc/systemd/system/
+	systemctl daemon-reload
 
 uninstall:
 	rm /usr/local/bin/hetzner-ddns.py

README.md

@@ -3,6 +3,8 @@
 This script finds this machine's hostname, public IPv4 and IPv6 addresses,
 then updates the corresponding DNS records on Hetzner.
 
+**Note:** *This script is not developed, maintained or supported by Hetzner.*
+
 ## Usage
 
 ```text
@@ -28,30 +30,39 @@ Options:
 
 The instructions below were tested on Ubuntu Linux 20.04 LTS. 
 
-1. Install `python3` and `pip`:
+1. Install Python and pip:
 
-    apt install python3
+```
+sudo apt install python3 python3-pip
+```
 
 2. Install package dependencies:
 
-    pip install docopt
+```
+sudo pip3 install docopt
+```
 
 3. Clone the repository somewhere:
 
-    cd /opt
-    git clone https://github.com/iSoron/hetzner-ddns.git
+```
+git clone https://github.com/iSoron/hetzner-ddns.git
+```
 
 4. Install the script system-wide:
 
-    cd hetzner-ddns
-    sudo make install
+```
+cd hetzner-ddns
+sudo make install
+```
 
 5. Create a configuration file in `/etc/hetzner-ddns.conf` with you API token. See `/etc/hetzner-ddns.conf.example` for an example.
 
 6. Run script and enable it during boot:
 
-    sudo systemctl start hetzner-ddns
-    sudo systemctl enable hetzner-ddns
+```
+sudo make start
+sudo make enable
+```
 
 ## License
 

etc/systemd/hetzner-ddns.service

@@ -4,8 +4,8 @@ After=network-online.target
 Wants=network-online.target
 
 [Service]
-Type=oneshot
-ExecStart=/usr/local/bin/hetzner-ddns.py
+Type=simple
+ExecStart=python3 -u /usr/local/bin/hetzner-ddns.py
 
 [Install]
 WantedBy=multi-user.target

hetzner-ddns.py

@@ -20,6 +20,7 @@ Options:
   --config=<file>       Read options from configuration file
   --disable-v4          Do not update IPv4 address
   --disable-v6          Do not update IPv6 address
+  --repeat=<s>          Update DNS again every S seconds
 """
 
 from docopt import docopt
@@ -30,6 +31,7 @@ import requests
 import socket
 import sys
 import configparser
+import time
 
 
 args = docopt(__doc__)
@@ -39,9 +41,9 @@ 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",
+        args["--config"],
+        os.path.join(basepath, "hetzner-ddns.conf"),
+        "/etc/hetzner-ddns.conf",
     ]
 
     for filename in candidate_config_files:
@@ -51,7 +53,7 @@ def merge_config_file():
             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
@@ -65,6 +67,7 @@ def merge_config_file():
 
     return args
 
+
 def merge_defaults():
     global args
     default_args = {
@@ -74,6 +77,7 @@ def merge_defaults():
         "--retry-attempts": 12,
         "--retry-delay": 5,
         "--hostname": socket.gethostname(),
+        "--repeat": 3600,
     }
 
     print("Applying default options:")
@@ -96,36 +100,40 @@ if args["--zone"] is None:
 merge_defaults()
 
 
-def get_addr(url,
-             retry=int(args["--retry-attempts"]),
-             delay=int(args["--retry-delay"])):
+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)
+    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"]})
+    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"]})
+    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:
@@ -139,7 +147,7 @@ def find_zone(name):
     for z in all_zones:
         if z["name"] == name:
             return z
-    raise(Exception("Zone not found: %s" % name))
+    raise (Exception("Zone not found: %s" % name))
 
 
 def update_record(record):
@@ -149,7 +157,7 @@ def update_record(record):
             "Content-Type": "application/json",
             "Auth-API-Token": args["--token"],
         },
-        data=json.dumps(record)
+        data=json.dumps(record),
     )
     response.raise_for_status()
 
@@ -161,13 +169,25 @@ def create_record(record):
             "Content-Type": "application/json",
             "Auth-API-Token": args["--token"],
         },
-        data=json.dumps(record)
+        data=json.dumps(record),
+    )
+    response.raise_for_status()
+
+
+def delete_record(rid):
+    response = requests.delete(
+        url=f"https://dns.hetzner.com/api/v1/records/{rid}",
+        headers={
+            "Content-Type": "application/json",
+            "Auth-API-Token": args["--token"],
+        }
     )
     response.raise_for_status()
 
 
 def main():
     kinds = []
+    delay = int(args["--repeat"])
 
     if not bool(args["--disable-v4"]):
         kinds += ["A"]
@@ -178,39 +198,42 @@ def main():
     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")
+    while True:
+        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 not None:
+                if rec["value"] == addr:
+                    print("Existing record is up-to-date")
+                    continue
+
+                print("Deleting existing %s record..." % kind)
+                delete_record(rec["id"])
+                print("    done")
+
             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)
+            create_record(
+                {
+                    "value": addr,
+                    "type": kind,
+                    "name": args["--hostname"],
+                    "zone_id": zone["id"],
+                    "ttl": args["--ttl"],
+                }
+            )
             print("    done")
 
+        print(f"Sleeping for {delay} seconds...")
+        time.sleep(delay)
 
 main()