Change PeersSerializer to SlugRelatedField

Get rid of PeersSerializer and just use SlugRelatedField,
which should be more a straightforward approach.

Other changes:
- cleanup code related to the already-removed api/v2/peers
endpoint
- add "hybrid" node type into more instance_peers test cases

awx/api/serializers.py

@@ -5374,11 +5374,6 @@ class InstanceNodeSerializer(BaseSerializer):
         fields = ('id', 'hostname', 'node_type', 'node_state', 'enabled')
 
 
-class PeersSerializer(serializers.StringRelatedField):
-    def to_internal_value(self, value):
-        return Instance.objects.get(hostname=value)
-
-
 class InstanceSerializer(BaseSerializer):
     show_capabilities = ['edit']
 
@@ -5387,7 +5382,7 @@ class InstanceSerializer(BaseSerializer):
     jobs_running = serializers.IntegerField(help_text=_('Count of jobs in the running or waiting state that are targeted for this instance'), read_only=True)
     jobs_total = serializers.IntegerField(help_text=_('Count of all jobs that target this instance'), read_only=True)
     health_check_pending = serializers.SerializerMethodField()
-    peers = PeersSerializer(many=True, required=False)
+    peers = serializers.SlugRelatedField(many=True, required=False, slug_field="hostname", queryset=Instance.objects.all())
 
     class Meta:
         model = Instance
@@ -5493,7 +5488,7 @@ class InstanceSerializer(BaseSerializer):
         if peers_from_control_nodes and node_type not in (Instance.Types.EXECUTION, Instance.Types.HOP):
             raise serializers.ValidationError(_("peers_from_control_nodes can only be enabled for execution or hop nodes."))
 
-        if node_type == Instance.Types.CONTROL:
+        if node_type in [Instance.Types.CONTROL, Instance.Types.HYBRID]:
             if self.instance and 'peers' in attrs and set(self.instance.peers.all()) != set(attrs['peers']):
                 raise serializers.ValidationError(
                     _("Setting peers manually for control nodes is not allowed. Enable peers_from_control_nodes on the hop and execution nodes instead.")

awx/api/views/__init__.py

@@ -4349,17 +4349,3 @@ class WorkflowApprovalDeny(RetrieveAPIView):
             return Response({"error": _("This workflow step has already been approved or denied.")}, status=status.HTTP_400_BAD_REQUEST)
         obj.deny(request)
         return Response(status=status.HTTP_204_NO_CONTENT)
-
-
-class PeersList(ListAPIView):
-    name = _("Peers")
-    model = models.InstanceLink
-    serializer_class = serializers.InstanceLinkSerializer
-    search_fields = ('source', 'target', 'link_state')
-
-
-class PeersDetail(RetrieveAPIView):
-    name = _("Peers Detail")
-    always_allow_superuser = True
-    model = models.InstanceLink
-    serializer_class = serializers.InstanceLinkSerializer