Add error handling when updating non-existing record

It can happen that a drone does not reach the AvailableState but only
the DownState. In this case, updating the record in Auditor does not
work, because no record has been created. In this case, Auditor returns
a 400 BAD REQUEST. This commit adds error handling for this specific
case. Other exceptions will not be handled.

tardis/plugins/auditor.py

@@ -8,9 +8,13 @@
 
 import logging
 import pytz
+import re
 from tzlocal import get_localzone
 
 
+REQWEST_ERROR = re.compile(r"Reqwest Error: HTTP status client error \((\d{3}).*\).*")
+
+
 class Auditor(Plugin):
     """
     The :py:class:`~tardis.plugins.auditor.Auditor` plugin is a collector for the
@@ -85,7 +89,21 @@ async def notify(self, state: State, resource_attributes: AttributeDict) -> None
                 .replace(tzinfo=self._local_timezone)
                 .astimezone(pytz.utc)
             )
-            await self._client.update(record)
+            try:
+                await self._client.update(record)
+            except RuntimeError as e:
+                reqwest_error_match = REQWEST_ERROR.match(str(e))
+                if reqwest_error_match:
+                    http_error_code = reqwest_error_match.group(1)
+                    if http_error_code == "400":
+                        self.logger.debug(
+                            f"Could not update record {record.record_id}, "
+                            "it probably does not exist in the database"
+                        )
+                    else:
+                        raise
+                else:
+                    raise
 
     def construct_record(self, resource_attributes: AttributeDict):
         """