Improve get_best_match_zone() to match by most matched components i…

…nstead of by length of domain (zappa#1193)

* 🔧 improve `get_best_match_zone()` to match by most matched components instead of by length of domain.

* ♻️ refactor multiple loops into single loop
🔧 add '.' to test_domain_name_match_component testcase HostedZones zone, 'Name'.

* 🔧 variable name clarification.

* 📝 add comments for clarification

* ✅ add testcase where match is short and longer zone name comes first.
🔧 fix case where exact match is ignored over longest.

* 🔥 remove unused import

tests/tests.py

@@ -1669,6 +1669,47 @@ def test_domain_name_match(self):
         )
         assert zone == "zone-public"
 
+    def test_domain_name_match_components(self):
+        # Simple sanity check
+        zone = Zappa.get_best_match_zone(
+            all_zones={
+                "HostedZones": [
+                    {
+                        "Name": "example.com.",
+                        "Id": "zone-correct",
+                        "Config": {"PrivateZone": False},
+                    },
+                    {
+                        "Name": "beta.example.com.",
+                        "Id": "zone-incorrect",
+                        "Config": {"PrivateZone": False},
+                    },
+                ]
+            },
+            domain="some-beta.example.com",
+        )
+        assert zone == "zone-correct"
+
+    def test_domain_name_match_components_short(self):
+        zone = Zappa.get_best_match_zone(
+            all_zones={
+                "HostedZones": [
+                    {
+                        "Name": "beta.example.com.",
+                        "Id": "zone-incorrect",
+                        "Config": {"PrivateZone": False},
+                    },
+                    {
+                        "Name": "example.com.",
+                        "Id": "zone-correct",
+                        "Config": {"PrivateZone": False},
+                    },
+                ]
+            },
+            domain="example.com",
+        )
+        assert zone == "zone-correct"
+
     ##
     # Let's Encrypt / ACME
     ##

zappa/core.py

@@ -3198,12 +3198,22 @@ def get_best_match_zone(all_zones, domain):
         """Return zone id which name is closer matched with domain name."""
 
         # Related: https://github.com/Miserlou/Zappa/issues/459
-        public_zones = [zone for zone in all_zones["HostedZones"] if not zone["Config"]["PrivateZone"]]
-
-        zones = {zone["Name"][:-1]: zone["Id"] for zone in public_zones if zone["Name"][:-1] in domain}
-        if zones:
-            keys = max(zones.keys(), key=lambda a: len(a))  # get longest key -- best match.
-            return zones[keys]
+        domain_components = domain.split(".")[::-1]  # match in reverse
+        candidate_zones = {}
+        for zone in all_zones["HostedZones"]:
+            if not zone["Config"]["PrivateZone"]:
+                public_zone_name = zone["Name"][:-1]  # zone "Name" expected to end with "." - remove "."
+                zone_components = public_zone_name.split(".")[::-1]  # reverse order
+                if all(z == d for z, d in zip(zone_components, domain_components)):
+                    # zones that match the shortest comparison considered a candidate
+                    candidate_zones[public_zone_name] = zone["Id"]
+
+        if candidate_zones:
+            if domain in candidate_zones:  # if exact match use it
+                best_match_key = domain
+            else:  # otherwise, use longest matched
+                best_match_key = max(candidate_zones.keys(), key=lambda a: len(a))  # get longest key -- best match.
+            return candidate_zones[best_match_key]
         else:
             return None