Revert "Revert "Revert "Add Python Reflection Client (#28443)" (#28878)" (#28879)" (#29023)

This reverts commit cf9be3d49d.
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  1. 55
      doc/python/server_reflection.md
  2. 9
      doc/python/sphinx/grpc_reflection.rst
  3. 4
      doc/server_reflection_tutorial.md
  4. 222
      src/python/grpcio_reflection/grpc_reflection/v1alpha/proto_reflection_descriptor_database.py
  5. 22
      src/python/grpcio_tests/tests/reflection/BUILD.bazel
  6. 147
      src/python/grpcio_tests/tests/reflection/_reflection_client_test.py
  7. 20
      src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
  8. 1
      src/python/grpcio_tests/tests/tests.json

@ -49,61 +49,6 @@ is working properly by using the [`grpc_cli` command line tool]:
please refer to the [`grpc_cli` documentation] and the
[C++ Server Reflection Tutorial].
## Use Server Reflection in a Python client
Server Reflection can be used by clients to get information about gRPC services
at runtime. We've provided a descriptor database called
[ProtoReflectionDescriptorDatabase](../../src/python/grpcio_reflection/v1alpha/proto_reflection_descriptor_database.h)
which implements the
[DescriptorDatabase](https://googleapis.dev/python/protobuf/latest/google/protobuf/descriptor_database.html#google.protobuf.descriptor_database.DescriptorDatabase)
interface. It manages the communication between clients and reflection services
and the storage of received information. Clients can use it as using a local
descriptor database.
- To use Server Reflection with ProtoReflectionDescriptorDatabase, first
initialize an instance with a channel.
```Python
import grpc
from grpc_reflection.v1alpha.proto_reflection_descriptor_database import ProtoReflectionDescriptorDatabase
channel = grpc.secure_channel(server_address, creds)
reflection_db = ProtoReflectionDescriptorDatabase(channel)
```
- Then use this instance to feed a
[DescriptorPool](https://googleapis.dev/python/protobuf/latest/google/protobuf/descriptor_pool.html#google.protobuf.descriptor_pool.DescriptorPool).
```Python
from google.protobuf.descriptor_pool import DescriptorPool
desc_pool = DescriptorPool(reflection_db)
```
- Example usage of this descriptor pool:
* Get Service/method descriptors.
```Python
service_desc = desc_pool.FindServiceByName("helloworld.Greeter")
method_desc = service_desc.FindMethodByName("helloworld.Greeter.SayHello")
```
* Get message type descriptors and create messages dynamically.
```Python
request_desc = desc_pool.FindMessageTypeByName("helloworld.HelloRequest")
request = MessageFactory(desc_pool).GetPrototype(request_desc)()
```
- You can also use the Reflection Database to list all the services:
```Python
services = reflection_db.get_services()
```
## Additional Resources
The [Server Reflection Protocol] provides detailed

@ -16,13 +16,4 @@ Refer to the GitHub `reflection example <https://github.com/grpc/grpc/blob/maste
Module Contents
---------------
Server-side
...........
.. automodule:: grpc_reflection.v1alpha.reflection
Client-side
...........
.. automodule:: grpc_reflection.v1alpha.proto_reflection_descriptor_database
:member-order: bysource

@ -187,7 +187,3 @@ descriptor database.
google::protobuf::Message* request = dmf.GetPrototype(request_desc)->New();
```
## Use Server Reflection in a Python client
See [Python Server Reflection](python/server_reflection.md).

@ -1,222 +0,0 @@
# Copyright 2022 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Reference implementation for reflection client in gRPC Python.
For usage instructions, see the Python Reflection documentation at
``doc/python/server_reflection.md``.
"""
import logging
from typing import Any, Dict, Iterable, List, Set
from google.protobuf.descriptor_database import DescriptorDatabase
from google.protobuf.descriptor_pb2 import FileDescriptorProto
import grpc
from grpc_reflection.v1alpha.reflection_pb2 import ExtensionNumberResponse
from grpc_reflection.v1alpha.reflection_pb2 import ExtensionRequest
from grpc_reflection.v1alpha.reflection_pb2 import FileDescriptorResponse
from grpc_reflection.v1alpha.reflection_pb2 import ListServiceResponse
from grpc_reflection.v1alpha.reflection_pb2 import ServerReflectionRequest
from grpc_reflection.v1alpha.reflection_pb2 import ServerReflectionResponse
from grpc_reflection.v1alpha.reflection_pb2 import ServiceResponse
from grpc_reflection.v1alpha.reflection_pb2_grpc import ServerReflectionStub
class ProtoReflectionDescriptorDatabase(DescriptorDatabase):
"""
A container and interface for receiving descriptors from a server's
Reflection service.
ProtoReflectionDescriptorDatabase takes a channel to a server with
Reflection service, and provides an interface to retrieve the Reflection
information. It implements the DescriptorDatabase interface.
It is typically used to feed a DescriptorPool instance.
"""
# Implementation based on C++ version found here (version tag 1.39.1):
# grpc/test/cpp/util/proto_reflection_descriptor_database.cc
# while implementing the Python interface given here:
# https://googleapis.dev/python/protobuf/3.17.0/google/protobuf/descriptor_database.html
def __init__(self, channel: grpc.Channel):
DescriptorDatabase.__init__(self)
self._logger = logging.getLogger(__name__)
self._stub = ServerReflectionStub(channel)
self._known_files: Set[str] = set()
self._cached_extension_numbers: Dict[str, List[int]] = dict()
def get_services(self) -> Iterable[str]:
"""
Get list of full names of the registered services.
Returns:
A list of strings corresponding to the names of the services.
"""
request = ServerReflectionRequest(list_services="")
response = self._do_one_request(request, key="")
list_services: ListServiceResponse = response.list_services_response
services: List[ServiceResponse] = list_services.service
return [service.name for service in services]
def FindFileByName(self, name: str) -> FileDescriptorProto:
"""
Find a file descriptor by file name.
This function implements a DescriptorDatabase interface, and is
typically not called directly; prefer using a DescriptorPool instead.
Args:
name: The name of the file. Typically this is a relative path ending in ".proto".
Returns:
A FileDescriptorProto for the file.
Raises:
KeyError: the file was not found.
"""
try:
return super().FindFileByName(name)
except KeyError:
pass
assert name not in self._known_files
request = ServerReflectionRequest(file_by_filename=name)
response = self._do_one_request(request, key=name)
self._add_file_from_response(response.file_descriptor_response)
return super().FindFileByName(name)
def FindFileContainingSymbol(self, symbol: str) -> FileDescriptorProto:
"""
Find the file containing the symbol, and return its file descriptor.
The symbol should be a fully qualified name including the file
descriptor's package and any containing messages. Some examples:
* "some.package.name.Message"
* "some.package.name.Message.NestedEnum"
* "some.package.name.Message.some_field"
This function implements a DescriptorDatabase interface, and is
typically not called directly; prefer using a DescriptorPool instead.
Args:
symbol: The fully-qualified name of the symbol.
Returns:
FileDescriptorProto for the file containing the symbol.
Raises:
KeyError: the symbol was not found.
"""
try:
return super().FindFileContainingSymbol(symbol)
except KeyError:
pass
# Query the server
request = ServerReflectionRequest(file_containing_symbol=symbol)
response = self._do_one_request(request, key=symbol)
self._add_file_from_response(response.file_descriptor_response)
return super().FindFileContainingSymbol(symbol)
def FindAllExtensionNumbers(self, extendee_name: str) -> Iterable[int]:
"""
Find the field numbers used by all known extensions of `extendee_name`.
This function implements a DescriptorDatabase interface, and is
typically not called directly; prefer using a DescriptorPool instead.
Args:
extendee_name: fully-qualified name of the extended message type.
Returns:
A list of field numbers used by all known extensions.
Raises:
KeyError: The message type `extendee_name` was not found.
"""
if extendee_name in self._cached_extension_numbers:
return self._cached_extension_numbers[extendee_name]
request = ServerReflectionRequest(
all_extension_numbers_of_type=extendee_name)
response = self._do_one_request(request, key=extendee_name)
all_extension_numbers: ExtensionNumberResponse = (
response.all_extension_numbers_response)
numbers = list(all_extension_numbers.extension_number)
self._cached_extension_numbers[extendee_name] = numbers
return numbers
def FindFileContainingExtension(
self, extendee_name: str,
extension_number: int) -> FileDescriptorProto:
"""
Find the file which defines an extension for the given message type
and field number.
This function implements a DescriptorDatabase interface, and is
typically not called directly; prefer using a DescriptorPool instead.
Args:
extendee_name: fully-qualified name of the extended message type.
extension_number: the number of the extension field.
Returns:
FileDescriptorProto for the file containing the extension.
Raises:
KeyError: The message or the extension number were not found.
"""
try:
return super().FindFileContainingExtension(extendee_name,
extension_number)
except KeyError:
pass
request = ServerReflectionRequest(
file_containing_extension=ExtensionRequest(
containing_type=extendee_name,
extension_number=extension_number))
response = self._do_one_request(request,
key=(extendee_name, extension_number))
file_desc = response.file_descriptor_response
self._add_file_from_response(file_desc)
return super().FindFileContainingExtension(extendee_name,
extension_number)
def _do_one_request(self, request: ServerReflectionRequest,
key: Any) -> ServerReflectionResponse:
response = self._stub.ServerReflectionInfo(iter([request]))
res = next(response)
if res.WhichOneof("message_response") == "error_response":
# Only NOT_FOUND errors are expected at this layer
error_code = res.error_response.error_code
assert (error_code == grpc.StatusCode.NOT_FOUND.value[0]
), "unexpected error response: " + repr(res.error_response)
raise KeyError(key)
return res
def _add_file_from_response(
self, file_descriptor: FileDescriptorResponse) -> None:
protos: List[bytes] = file_descriptor.file_descriptor_proto
for proto in protos:
desc = FileDescriptorProto()
desc.ParseFromString(proto)
if desc.name not in self._known_files:
self._logger.info("Loading descriptors from file: %s",
desc.name)
self._known_files.add(desc.name)
self.Add(desc)

@ -17,7 +17,7 @@ package(default_visibility = ["//visibility:public"])
py_test(
name = "_reflection_servicer_test",
size = "small",
size = "medium",
srcs = ["_reflection_servicer_test.py"],
imports = ["../../"],
main = "_reflection_servicer_test.py",
@ -32,23 +32,3 @@ py_test(
requirement("protobuf"),
],
)
py_test(
name = "_reflection_client_test",
size = "small",
srcs = ["_reflection_client_test.py"],
imports = ["../../"],
main = "_reflection_client_test.py",
python_version = "PY3",
deps = [
"//src/proto/grpc/testing:empty_py_pb2",
"//src/proto/grpc/testing:py_messages_proto",
"//src/proto/grpc/testing:test_py_pb2_grpc",
"//src/proto/grpc/testing/proto2:empty2_extensions_proto",
"//src/proto/grpc/testing/proto2:empty2_proto",
"//src/python/grpcio/grpc:grpcio",
"//src/python/grpcio_reflection/grpc_reflection/v1alpha:grpc_reflection",
"//src/python/grpcio_tests/tests/unit:test_common",
requirement("protobuf"),
],
)

@ -1,147 +0,0 @@
# Copyright 2022 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Tests of grpc_reflection.v1alpha.reflection."""
import unittest
from google.protobuf.descriptor_pool import DescriptorPool
import grpc
from grpc_reflection.v1alpha import reflection
from grpc_reflection.v1alpha.proto_reflection_descriptor_database import \
ProtoReflectionDescriptorDatabase
from src.proto.grpc.testing import test_pb2
# Needed to load the EmptyWithExtensions message
from src.proto.grpc.testing.proto2 import empty2_extensions_pb2
from tests.unit import test_common
_PROTO_PACKAGE_NAME = "grpc.testing"
_PROTO_FILE_NAME = "src/proto/grpc/testing/test.proto"
_EMPTY_PROTO_FILE_NAME = "src/proto/grpc/testing/empty.proto"
_INVALID_FILE_NAME = "i-do-not-exist.proto"
_EMPTY_PROTO_SYMBOL_NAME = "grpc.testing.Empty"
_INVALID_SYMBOL_NAME = "IDoNotExist"
_EMPTY_EXTENSIONS_SYMBOL_NAME = "grpc.testing.proto2.EmptyWithExtensions"
class ReflectionClientTest(unittest.TestCase):
def setUp(self):
self._server = test_common.test_server()
self._SERVICE_NAMES = (
test_pb2.DESCRIPTOR.services_by_name["TestService"].full_name,
reflection.SERVICE_NAME,
)
reflection.enable_server_reflection(self._SERVICE_NAMES, self._server)
port = self._server.add_insecure_port("[::]:0")
self._server.start()
self._channel = grpc.insecure_channel("localhost:%d" % port)
self._reflection_db = ProtoReflectionDescriptorDatabase(self._channel)
self.desc_pool = DescriptorPool(self._reflection_db)
def tearDown(self):
self._server.stop(None)
self._channel.close()
def testListServices(self):
services = self._reflection_db.get_services()
self.assertCountEqual(self._SERVICE_NAMES, services)
def testReflectionServiceName(self):
self.assertEqual(reflection.SERVICE_NAME,
"grpc.reflection.v1alpha.ServerReflection")
def testFindFile(self):
file_name = _PROTO_FILE_NAME
file_desc = self.desc_pool.FindFileByName(file_name)
self.assertEqual(file_name, file_desc.name)
self.assertEqual(_PROTO_PACKAGE_NAME, file_desc.package)
self.assertEqual("proto3", file_desc.syntax)
self.assertIn("TestService", file_desc.services_by_name)
file_name = _EMPTY_PROTO_FILE_NAME
file_desc = self.desc_pool.FindFileByName(file_name)
self.assertEqual(file_name, file_desc.name)
self.assertEqual(_PROTO_PACKAGE_NAME, file_desc.package)
self.assertEqual("proto3", file_desc.syntax)
self.assertIn("Empty", file_desc.message_types_by_name)
def testFindFileError(self):
with self.assertRaises(KeyError):
self.desc_pool.FindFileByName(_INVALID_FILE_NAME)
def testFindMessage(self):
message_name = _EMPTY_PROTO_SYMBOL_NAME
message_desc = self.desc_pool.FindMessageTypeByName(message_name)
self.assertEqual(message_name, message_desc.full_name)
self.assertTrue(message_name.endswith(message_desc.name))
def testFindMessageError(self):
with self.assertRaises(KeyError):
self.desc_pool.FindMessageTypeByName(_INVALID_SYMBOL_NAME)
def testFindServiceFindMethod(self):
service_name = self._SERVICE_NAMES[0]
service_desc = self.desc_pool.FindServiceByName(service_name)
self.assertEqual(service_name, service_desc.full_name)
self.assertTrue(service_name.endswith(service_desc.name))
file_name = _PROTO_FILE_NAME
file_desc = self.desc_pool.FindFileByName(file_name)
self.assertIs(file_desc, service_desc.file)
method_name = "EmptyCall"
self.assertIn(method_name, service_desc.methods_by_name)
method_desc = service_desc.FindMethodByName(method_name)
self.assertIs(method_desc, service_desc.methods_by_name[method_name])
self.assertIs(service_desc, method_desc.containing_service)
self.assertEqual(method_name, method_desc.name)
self.assertTrue(method_desc.full_name.endswith(method_name))
empty_message_desc = self.desc_pool.FindMessageTypeByName(
_EMPTY_PROTO_SYMBOL_NAME)
self.assertEqual(empty_message_desc, method_desc.input_type)
self.assertEqual(empty_message_desc, method_desc.output_type)
def testFindServiceError(self):
with self.assertRaises(KeyError):
self.desc_pool.FindServiceByName(_INVALID_SYMBOL_NAME)
def testFindMethodError(self):
service_name = self._SERVICE_NAMES[0]
service_desc = self.desc_pool.FindServiceByName(service_name)
with self.assertRaises(KeyError):
service_desc.FindMethodByName(_INVALID_SYMBOL_NAME)
def testFindExtensionNotImplemented(self):
"""
Extensions aren't implemented in Protobuf for Python.
For now, simply assert that indeed they don't work.
"""
message_name = _EMPTY_EXTENSIONS_SYMBOL_NAME
message_desc = self.desc_pool.FindMessageTypeByName(message_name)
self.assertEqual(message_name, message_desc.full_name)
self.assertTrue(message_name.endswith(message_desc.name))
extension_field_descs = self.desc_pool.FindAllExtensions(message_desc)
self.assertEqual(0, len(extension_field_descs))
with self.assertRaises(KeyError):
self.desc_pool.FindExtensionByName(message_name)
if __name__ == "__main__":
unittest.main(verbosity=2)

@ -51,6 +51,16 @@ def _file_descriptor_to_proto(descriptor):
'ProtoBuf descriptor has moved on from Python2')
class ReflectionServicerTest(unittest.TestCase):
# TODO(https://github.com/grpc/grpc/issues/17844)
# Bazel + Python 3 will result in creating two different instance of
# DESCRIPTOR for each message. So, the equal comparison between protobuf
# returned by stub and manually crafted protobuf will always fail.
def _assert_sequence_of_proto_equal(self, x, y):
self.assertSequenceEqual(
tuple(proto.SerializeToString() for proto in x),
tuple(proto.SerializeToString() for proto in y),
)
def setUp(self):
self._server = test_common.test_server()
reflection.enable_server_reflection(_SERVICE_NAMES, self._server)
@ -85,7 +95,7 @@ class ReflectionServicerTest(unittest.TestCase):
error_message=grpc.StatusCode.NOT_FOUND.value[1].encode(),
)),
)
self.assertEqual(expected_responses, responses)
self._assert_sequence_of_proto_equal(expected_responses, responses)
def testFileBySymbol(self):
requests = (
@ -109,7 +119,7 @@ class ReflectionServicerTest(unittest.TestCase):
error_message=grpc.StatusCode.NOT_FOUND.value[1].encode(),
)),
)
self.assertEqual(expected_responses, responses)
self._assert_sequence_of_proto_equal(expected_responses, responses)
def testFileContainingExtension(self):
requests = (
@ -138,7 +148,7 @@ class ReflectionServicerTest(unittest.TestCase):
error_message=grpc.StatusCode.NOT_FOUND.value[1].encode(),
)),
)
self.assertEqual(expected_responses, responses)
self._assert_sequence_of_proto_equal(expected_responses, responses)
def testExtensionNumbersOfType(self):
requests = (
@ -163,7 +173,7 @@ class ReflectionServicerTest(unittest.TestCase):
error_message=grpc.StatusCode.NOT_FOUND.value[1].encode(),
)),
)
self.assertEqual(expected_responses, responses)
self._assert_sequence_of_proto_equal(expected_responses, responses)
def testListServices(self):
requests = (reflection_pb2.ServerReflectionRequest(list_services='',),)
@ -174,7 +184,7 @@ class ReflectionServicerTest(unittest.TestCase):
service=tuple(
reflection_pb2.ServiceResponse(name=name)
for name in _SERVICE_NAMES))),)
self.assertEqual(expected_responses, responses)
self._assert_sequence_of_proto_equal(expected_responses, responses)
def testReflectionServiceName(self):
self.assertEqual(reflection.SERVICE_NAME,

@ -18,7 +18,6 @@
"protoc_plugin._split_definitions_test.SplitProtoProtoBeforeGrpcProtocStyleTest",
"protoc_plugin._split_definitions_test.SplitProtoSingleProtocExecutionProtocStyleTest",
"protoc_plugin.beta_python_plugin_test.PythonPluginTest",
"reflection._reflection_client_test.ReflectionClientTest",
"reflection._reflection_servicer_test.ReflectionServicerTest",
"status._grpc_status_test.StatusTest",
"testing._client_test.ClientTest",

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