fix(snmp): limit SNMP communities

As Sonic devices do not accept more than one SNMP community, we prefer to limit to the lowest
common denominator.

netbox_cmdb/netbox_cmdb/api/snmp/serializers.py

@@ -1,9 +1,10 @@
 """Route Policy serializers."""
 
-from rest_framework.serializers import ModelSerializer
+from rest_framework.serializers import ModelSerializer, ValidationError
 
 from netbox_cmdb.models.snmp import SNMP, SNMPCommunity
 from netbox_cmdb.api.common_serializers import CommonDeviceSerializer
+from netbox_cmdb.constants import MAX_COMMUNITY_PER_DEVICE
 
 
 class SNMPCommunitySerializer(ModelSerializer):
@@ -37,3 +38,10 @@ class SNMPSerializer(ModelSerializer):
     class Meta:
         model = SNMP
         fields = "__all__"
+
+    def validate_community_list(self, value):
+        if len(value) > MAX_COMMUNITY_PER_DEVICE:
+            raise ValidationError(
+                f"You cannot select more than {MAX_COMMUNITY_PER_DEVICE} SNMP Communities."
+            )
+        return value

netbox_cmdb/netbox_cmdb/constants.py

@@ -1,2 +1,5 @@
 BGP_MIN_ASN = 1
 BGP_MAX_ASN = 4294967294
+
+# As Sonic device don't support more than 1 community
+MAX_COMMUNITY_PER_DEVICE = 1

netbox_cmdb/netbox_cmdb/forms.py

@@ -7,6 +7,7 @@
 from django.utils.translation import gettext as _
 from extras.models import Tag
 from netbox_cmdb.models.snmp import SNMP, SNMPCommunity
+from netbox_cmdb.constants import MAX_COMMUNITY_PER_DEVICE
 from utilities.forms import DynamicModelMultipleChoiceField
 from utilities.forms.fields import DynamicModelChoiceField, MultipleChoiceField
 
@@ -93,6 +94,14 @@ class Meta:
         model = SNMP
         fields = ["device", "community_list", "location", "contact"]
 
+    def clean_community_list(self):
+        community_list = self.cleaned_data.get("community_list")
+        if len(community_list) > MAX_COMMUNITY_PER_DEVICE:
+            raise forms.ValidationError(
+                f"You cannot select more than {MAX_COMMUNITY_PER_DEVICE} SNMP Communities."
+            )
+        return community_list
+
 
 class SNMPCommunityGroupForm(NetBoxModelForm):
     class Meta:

netbox_cmdb/netbox_cmdb/tests/snmp/test_snmp_serializer.py

@@ -34,3 +34,19 @@ def test_create(self):
         assert conf.contact == "my_team"
         assert conf.community_list.all()[0] == community1
         assert conf.device == self.device1
+
+        data = {"name": "my_comm2", "community": "my_community2", "type": "readonly"}
+        snmpcommunity_serializer = SNMPCommunitySerializer(data=data)
+        assert snmpcommunity_serializer.is_valid() == True
+        snmpcommunity_serializer.save()
+        community2 = SNMPCommunity.objects.get(name="my_comm2")
+
+        data = {
+            "device": self.device2.pk,
+            "community_list": [community1.pk, community2.pk],
+            "location": "my_location",
+            "contact": "my_team",
+        }
+
+        snmp_serializer = SNMPSerializer(data=data)
+        assert snmp_serializer.is_valid() == False