feat: only update if destination changed

src/netcup_dns/main.py

@@ -33,19 +33,44 @@ def main():
                 type_ = cfg[domain]['type'].upper()
                 if type_ == 'A':
                     destination = external_ipv4()
-                    update_record_destination(api, domain, hostname, type_, destination=destination)
+                    if update_record_destination(api, domain, hostname, type_, destination=destination):
                         print(f'Set {hostname}.{domain} {type_} record to {destination}')
+                    else:
+                        print(f'The {hostname}.{domain} {type_} record points already to {destination}.')
                 else:
                     raise Exception(f'DNS record type {type_} is not supported.')
 
 
-def update_record_destination(api: Client, domain: str, hostname: str, type_: str, destination: str) -> None:
+def update_record_destination(api: Client, domain: str, hostname: str, type_: str, destination: str) -> bool:
+    """
+    Updates the `destination` of the DNS record identified by `domain`, `hostname` and `type`.
+
+    :param api:
+    :param domain:
+    :param hostname:
+    :param type_:
+    :param destination:
+    :return: True if `destination` differs from the old destination.
+    """
     record = get_record(api, domain, hostname, type_)
+    if record.destination == destination:
+        # The new destination is identical with the current one.
+        # Thus, we don't need to call the api.update_dns_record() method.
+        return False
+    else:
         record.destination = destination
         api.update_dns_record(domain, record)
+        return True
 
 
 def get_record(api: Client, domain: str, hostname: str, type_: str) -> DNSRecord:
+    """
+    :param api:
+    :param domain:
+    :param hostname:
+    :param type_:
+    :return: The DNS record identified by `domain`, `hostname` and `type`.
+    """
     records: list[DNSRecord] = api.dns_records(domain)
     record: DNSRecord