【Python】建立gRPC服务端与.Net Core 客户端

由于需要接入其他平台的OAuth 2.0，还要提供RESTful API获取VMware vSphere的数据，这块内容，.net core我更熟悉，通过上两篇，我们知道这里只能通过python去获取数据了，那么我面临的问题就是python与.net core的数据通信:

• 方法一：使用Python的web轻量级框架Flask提供api，供aspi.net core调用
• 方法二：使用Python建立gRPC的服务端，供asp.net core调用

我选择后者，因为之前有gRPC的基础：

1.更新pip

python -m pip install --upgrade pip

2.安装grpc

python -m pip install grpcio

3.安装gRPC-tool

python -m pip install grpcio-tools

4.编写.proto文件

如果对ProtoBuf不熟悉，请参考另外一篇博文【gRPC】ProtoBuf 语言快速学习指南

主要是要记住几个关键要点：

• service

  • service Query {
      rpc ListHostStat (google.protobuf.Empty) returns (HostStatReply) {}
    }
    

• message

  • 作为rpc服务的请求和返回

syntax = "proto3";

import "google/protobuf/empty.proto";

option csharp_namespace  = "Grpc.VmwareVsphere";

package Vcenter;

service Query {
  rpc ListHostStat (google.protobuf.Empty) returns (HostStatReply) {}
}

message HostStatReply {
    int32  abnormalHostAmount = 1;
    int32  hostAmount = 2;
    int32  normalHostAmount = 3;
}

5.生成python服务端代码

cd python-dir
python -m grpc_tools.protoc -I ../protos --python_out=. --grpc_python_out=. ../protos/vcenter.proto

这里会生成两个python文件

[proto-file-name]_pb2.py

[proto-file-name]_pb2_grpc.py

6.编写服务端代码

6.1 引入grpc包与生成的python文件

import grpc
import vcenter_pb2
import vcenter_pb2_grpc

官方还引入了

from concurrent import futures
import logging

第一个不知道在干啥，先不细究，第二个应该是写日志的

6.2 实现服务端类

class Query(vcenter_pb2_grpc.QueryServicer):
    def ListHostStat(self, request, context):
        hostquery = VmwareHost(host, user, pwd, port)
        hostquery.list_host_state_num()
        return vcenter_pb2.HostStatReply(
            abnormalHostAmount=hostquery.abnormalHostAmount,
            hostAmount=hostquery.hostAmount,
            normalHostAmount=hostquery.normalHostAmount,
        )

类比C#实现服务端类，大概都是继承一个父类，然后重写基类方法：

class QueryImpl : Query.QueryBase
{
    public override Task<HostStatReply> ListHostStat(NoPara request, ServerCallContext context)
    {
        return Task.FromResult(new HostStatReply { ... });
    }
}

整体看下python服务端代码吧

from concurrent import futures
import logging

import grpc
import vcenter_pb2
import vcenter_pb2_grpc
from vmware_query import VmwareHost


class Query(vcenter_pb2_grpc.QueryServicer):
    def ListHostStat(self, request, context):
        hostquery = VmwareHost(host, user, pwd, port)
        hostquery.list_host_state_num()
        return vcenter_pb2.HostStatReply(
            abnormalHostAmount=hostquery.abnormalHostAmount,
            hostAmount=hostquery.hostAmount,
            normalHostAmount=hostquery.normalHostAmount,
        )

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    vcenter_pb2_grpc.add_QueryServicer_to_server(Query(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    print("grpc server start success..  listen port:50051")
    server.wait_for_termination()


host = "192.168.0.110"
user = "....l"
pwd = "....!"
port = 443
if __name__ == '__main__':
    logging.basicConfig()
    serve()

7.启动

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    vcenter_pb2_grpc.add_QueryServicer_to_server(Query(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    print("grpc server start success..  listen port:50051")
    server.wait_for_termination()

类比C#实现的服务端

Server server = new Server
{
    Services = { Query.BindService(new QueryImpl()) },
    Ports = { new ServerPort("localhost", 50051, ServerCredentials.Insecure) }
};
server.Start();

Console.WriteLine("Query server listening on port " + 50051);
Console.WriteLine("Press any key to stop the server...");
Console.ReadKey();

server.ShutdownAsync().Wait();

8.编写客户端代码

客户端是Asp.net Core，在Webapi中调用gRPC服务

8.1 安装nuget包

参考【gRPC】 在.Net core中使用gRPC 4.1 安装包

8.2 编辑csproj文件

引入与服务端相同的proto文件

  <ItemGroup>
    <Protobuf Include="....protos*.proto" GrpcServices="Client" Link="Protos\%(RecursiveDir)%(Filename)%(Extension)" />
  </ItemGroup>

8.3 编码

[HttpGet]
[Produces("application/json")]
public async Task<Host> GetHostAsync()
{
    AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);
    var channel = GrpcChannel.ForAddress("http://localhost:50051");
    var queryClient = new QueryClient(channel);
    var reply = await queryClient.ListHostStatAsync(new Grpc.VmwareVsphere.NoPara());
    Console.WriteLine("StatService 服务返回异常主机数据: " + reply.AbnormalHostAmount);
    Console.WriteLine("StatService 服务返回主机数据: " + reply.HostAmount);
    Console.WriteLine("StatService 服务返回正常主机数据: " + reply.NormalHostAmount);
    return new Host() { 
        AbnormalHostAmount=reply.AbnormalHostAmount,
        HostAmount=reply.HostAmount,
        NormalHostAmount=reply.NormalHostAmount
    };
}

参考链接

https://www.velotio.com/engineering-blog/grpc-implementation-using-python

https://www.grpc.io/docs/languages/python/quickstart/