fix: multi protocol gateway supports monitoring

jina/serve/runtimes/gateway/composite/gateway.py

@@ -1,5 +1,5 @@
 import copy
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from jina.serve.gateway import BaseGateway
 
@@ -21,10 +21,13 @@ def __init__(
         self.gateways: List[BaseGateway] = []
         for port, protocol in zip(self.ports, self.protocols):
             gateway_cls = _get_gateway_class(protocol)
-            runtime_args = copy.deepcopy(self.runtime_args)
+            # ignore metrics_registry since it is not copyable
+            runtime_args = self._deepcopy_with_ignore_attrs(
+                self.runtime_args, ['metrics_registry']
+            )
             runtime_args.port = [port]
             runtime_args.protocol = [protocol]
-            gateway_kwargs = copy.deepcopy(kwargs)
+            gateway_kwargs = {k: v for k, v in kwargs.items() if k != 'runtime_args'}
             gateway_kwargs['runtime_args'] = dict(vars(runtime_args))
             gateway = gateway_cls(**gateway_kwargs)
             self.gateways.append(gateway)
@@ -46,6 +49,22 @@ async def run_server(self):
         for gateway in self.gateways:
             await gateway.run_server()
 
+    @staticmethod
+    def _deepcopy_with_ignore_attrs(obj: Any, ignore_attrs: List[str]) -> Any:
+        """Deep copy an object and ignore some attributes
+
+        :param obj: the object to copy
+        :param ignore_attrs: the attributes to ignore
+        :return: the copied object
+        """
+
+        memo = {}
+        for k in ignore_attrs:
+            if hasattr(obj, k):
+                memo[id(getattr(obj, k))] = None  # getattr(obj, k)
+
+        return copy.deepcopy(obj, memo)
+
     @property
     def _should_exit(self) -> bool:
         should_exit_values = [

tests/unit/orchestrate/flow/flow-construct/test_flow_multiprotocol.py

@@ -118,3 +118,14 @@ def test_flow_multiprotocol_ports_protocols_mismatch():
         'You need to specify as much protocols as ports if you want to use a jina built-in gateway'
         in err_info.value.args[0]
     )
+
+
+def test_flow_multiprotocol_with_monitoring():
+    ports = [random_port(), random_port(), random_port()]
+    protocols = PROTOCOLS
+    flow = Flow().config_gateway(port=ports, protocol=protocols, monitoring=True)
+
+    with flow:
+        for port, protocol in zip(ports, protocols):
+            client = Client(port=port, protocol=protocol)
+            client.post('/', inputs=[Document()])