Handle invalid cache

When the zone has been deleted and recreated manually between two updates,
the record_id will be different. We detect an invalid cache in this case
and try to get zone records again from CloudFlare or create it if getting
the zone_id failed. Fixes #6 #7.

README.md

@@ -25,6 +25,19 @@ Or you can use [the Docker image](https://hub.docker.com/repository/docker/kissg
 $ docker run --rm -it kissgyorgy/cloudflare-dyndns --help
 ```
 
+# Note
+
+If you use this script, it "takes over" the handling of the record of those
+domains you specified, which means it will update existing records and create
+missing ones.
+
+You should not change A or AAAA records manually or with other scripts, because
+the changes will be overwritten.
+
+I decided to make it work this way, because I think most users expect this
+behavior, but if you have a different use case,
+[let me know!](https://github.com/kissgyorgy/cloudflare-dyndns/issues/new)
+
 ## Command line interface
 
 ```

cloudflare_dyndns/cli.py

@@ -42,34 +42,47 @@ def update_domains(
     cf: CloudFlareWrapper, domains: List[str], ip_cache: IPCache, current_ip: IPAddress,
 ):
     success = True
+
     for domain in domains:
-        try:
-            zone_record = ip_cache.updated_domains[domain]
-            zone_id = zone_record.zone_id
-            record_id = zone_record.record_id
-        except KeyError:
+        get_record_failed = False
+        update_record_failed = False
+
+        cache_record = ip_cache.updated_domains.get(domain)
+
+        if cache_record is not None:
+            zone_id = cache_record.zone_id
+            record_id = cache_record.record_id
+            try:
+                cf.update_record(domain, current_ip, zone_id, record_id)
+            except CloudFlare.exceptions.CloudFlareAPIError:
+                printer.error("Invalid cache, deleting")
+                del ip_cache.updated_domains[domain]
+                update_record_failed = True
+
+        if cache_record is None or update_record_failed:
             try:
                 zone_id = cf.get_zone_id(domain)
-            except CloudFlareError as e:
+            except CloudFlareError:
+                # TODO: try to create zone?
                 success = False
                 continue
 
             try:
                 record_id = cf.get_record_id(domain, get_record_type(current_ip))
-                zone_record = ZoneRecord(zone_id=zone_id, record_id=record_id)
-            except CloudFlareError as e:
+            except CloudFlareError:
                 try:
                     record_id = cf.create_record(domain, current_ip)
-                except CloudFlare.exceptions.CloudFlareAPIError as e:
+                except CloudFlare.exceptions.CloudFlareAPIError:
                     success = False
-                continue
-
-        try:
-            cf.update_record(domain, current_ip, zone_id, record_id)
-        except Exception as e:
-            success = False
-            continue
+                    continue
+            else:
+                try:
+                    cf.update_record(domain, current_ip, zone_id, record_id)
+                except CloudFlare.exceptions.CloudFlareAPIError:
+                    success = False
+                    continue
 
+        zone_record = ZoneRecord(zone_id=zone_id, record_id=record_id)
         ip_cache.updated_domains[domain] = zone_record
 
     return success