扩展gRPC支持consul服务发现和Polly策略

gRPC由于需要用工具生成代码实现,可开发性不是很高,在扩展这方面不是很友好

最近研究了下,进行了扩展,不需要额外的工具生成,直接使用默认Grpc.Tools生成的代理类即可

客户端目标:

能配置consul地址和服务名称,在调用client时能正确请求到真实的服务地址
在调用方法时,能使用Polly策略重试,超时,和熔断

查看gRPC生成的代码,可以看到Client实例化有有两个构造方法,以测试为例

/// <summary>Creates a new client for Greeter</summary>
      /// <param name="channel">The channel to use to make remote calls.</param>
      public GreeterClient(grpc::ChannelBase channel) : base(channel)
      {
      }
      /// <summary>Creates a new client for Greeter that uses a custom <c>CallInvoker</c>.</summary>
      /// <param name="callInvoker">The callInvoker to use to make remote calls.</param>
      public GreeterClient(grpc::CallInvoker callInvoker) : base(callInvoker)
      {
      }

1.可传入一个ChannelBase实例化

2.可传入一个CallInvoker实例化

Channel可实现为

Channel CreateChannel(string address)
        {
            var channelOptions = new List<ChannelOption>()
                    {
                        new ChannelOption(ChannelOptions.MaxReceiveMessageLength, int.MaxValue),
                        new ChannelOption(ChannelOptions.MaxSendMessageLength, int.MaxValue),
                    };
            var channel = new Channel(address, ChannelCredentials.Insecure, channelOptions);
            return channel;
        }

在这里,可以从consul地址按服务名获取真实的服务地址,生成Channel

CallInvoker为一个抽象类,若要对方法执行过程干预,则需要重写这个方法,大致实现为

public class GRpcCallInvoker : CallInvoker
    {
        public readonly Channel Channel;
        public GRpcCallInvoker(Channel channel)
        {
            Channel = GrpcPreconditions.CheckNotNull(channel); 
        }

        public override TResponse BlockingUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.BlockingUnaryCall(CreateCall(method, host, options), request);
        }

        public override AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.AsyncUnaryCall(CreateCall(method, host, options), request);
        }

        public override AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.AsyncServerStreamingCall(CreateCall(method, host, options), request);
        }

        public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
        {
            return Calls.AsyncClientStreamingCall(CreateCall(method, host, options));
        }

        public override AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
        {
            return Calls.AsyncDuplexStreamingCall(CreateCall(method, host, options));
        }

        protected virtual CallInvocationDetails<TRequest, TResponse> CreateCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
            where TRequest : class 
            where TResponse : class
        {
            return new CallInvocationDetails<TRequest, TResponse>(Channel, method, host, options);
        }
    }

这里可以传入上面创建的Channel,在CreateCall方法里,则可以对调用方法进行控制

完整实现为

public class GRpcCallInvoker : CallInvoker
    {
        GrpcClientOptions _options;
        IGrpcConnect _grpcConnect;
        public GRpcCallInvoker(IGrpcConnect grpcConnect)
        {
            _options = grpcConnect.GetOptions();
            _grpcConnect = grpcConnect;
        }

        public override TResponse BlockingUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.BlockingUnaryCall(CreateCall(method, host, options), request);
        }

        public override AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.AsyncUnaryCall(CreateCall(method, host, options), request);
        }

        public override AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
        {
            return Calls.AsyncServerStreamingCall(CreateCall(method, host, options), request);
        }

        public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
        {
            return Calls.AsyncClientStreamingCall(CreateCall(method, host, options));
        }

        public override AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
        {
            return Calls.AsyncDuplexStreamingCall(CreateCall(method, host, options));
        }

        protected virtual CallInvocationDetails<TRequest, TResponse> CreateCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options)
            where TRequest : class
            where TResponse : class
        {
            var methodName = $"{method.ServiceName}.{method.Name}";
            var key = methodName.Substring(methodName.IndexOf(".") + 1).ToLower();
            var a = _options.MethodPolicies.TryGetValue(key, out PollyAttribute methodPollyAttr);
            if (!a)
            {
                _options.MethodPolicies.TryGetValue("", out methodPollyAttr);
            }
            CallOptions options2;
            //重写header
            if (options.Headers != null)
            {
                options2 = options;
            }
            else
            {
                options2 = new CallOptions(_grpcConnect.GetMetadata(), options.Deadline, options.CancellationToken);
            }

            var pollyData = PollyExtension.Invoke(methodPollyAttr, () =>
            {
                var callRes = new CallInvocationDetails<TRequest, TResponse>(_grpcConnect.GetChannel(), method, host, options2);
                return new PollyExtension.PollyData<CallInvocationDetails<TRequest, TResponse>>() { Data = callRes };
            }, $"{methodName}");
            var response = pollyData.Data;
            if (!string.IsNullOrEmpty(pollyData.Error))
            {
                throw new Exception(pollyData.Error);
            }
            return response;
            //return new CallInvocationDetails<TRequest, TResponse>(Channel.Invoke(), method, host, options2);
        }
    }

其中传入了PollyAttribute,由PollyExtension.Invoke来完成Polly策略的实现,具体代码可在源码里找到

从上面代码可以看到,CallInvoker里可以传入了IGrpcConnect,由方法IGrpcConnect.GetChannel()获取Channel

Client实例化

.net FrameWork实现为

public T GetClient<T>()
        {
            var a = instanceCache.TryGetValue(typeof(T), out object instance);
            if (!a)
            {
                var grpcCallInvoker = new GRpcCallInvoker(this);
                instance = System.Activator.CreateInstance(typeof(T), grpcCallInvoker);
                instanceCache.TryAdd(typeof(T), instance);
            }
            return (T)instance;
        }

core则简单点,直接注入实现

var client = provider.GetService<Greeter.GreeterClient>();

服务端注册

和其它服务注册一样,填入正确的服务地址和名称就行了,但是在Check里得改改,gRPC的健康检查参数是不同的,并且在consul客户端里没有这个参数,得自已写

以下代码是我封装过的,可查看源码

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGrpcService<GreeterService>();
                endpoints.MapGrpcService<HealthCheckService>();
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");
                });
            });

            //注册服务
            var consulClient = new CRL.Core.ConsulClient.Consul("http://localhost:8500");
            var info = new CRL.Core.ConsulClient.ServiceRegistrationInfo
            {
                Address = "127.0.0.1",
                Name = "grpcServer",
                ID = "grpcServer1",
                Port = 50001,
                Tags = new[] { "v1" },
                Check = new CRL.Core.ConsulClient.CheckRegistrationInfo()
                {
                    GRPC = "127.0.0.1:50001",
                    Interval = "10s",
                    GRPCUseTLS = false,
                    DeregisterCriticalServiceAfter = "90m"
                }
            };
            consulClient.DeregisterService(info.ID);
            var a = consulClient.RegisterService(info);

        }

客户端完整封装代码为

core扩展方法,设置GrpcClientOptions来配置consul地址和Polly策略,直接注入了Client类型

同时添加了统一header传递,使整个服务都能用一个头发送请求,不用再在方法后面跟参数

public static class GrpcExtensions
    {
        public static void AddGrpcExtend(this IServiceCollection services, Action<GrpcClientOptions> setupAction, params Assembly[] assemblies)
        {
            services.Configure(setupAction);
            services.AddSingleton<IGrpcConnect, GrpcConnect>();
            services.AddScoped<CallInvoker, GRpcCallInvoker>();
            foreach (var assembyle in assemblies)
            {
                var types = assembyle.GetTypes();
                foreach (var type in types)
                {
                    if(typeof(ClientBase).IsAssignableFrom(type))
                    {
                        services.AddSingleton(type);
                    }
                }
            }
        }
    }

class Program
    {
        static IServiceProvider provider;
        static Program()
        {
            var builder = new ConfigurationBuilder();

            var configuration = builder.Build();

            var services = new ServiceCollection();
            services.AddSingleton<IConfiguration>(configuration);
            services.AddOptions();

            services.AddGrpcExtend(op =>
            {
                op.Host = "127.0.0.1";
                op.Port = 50001;
                op.UseConsulDiscover("http://localhost:8500", "grpcServer");//使用consul服务发现
                op.AddPolicy("Greeter.SayHello", new CRL.Core.Remoting.PollyAttribute() { RetryCount = 3 });//定义方法polly策略
            }, System.Reflection.Assembly.GetExecutingAssembly());

            provider = services.BuildServiceProvider();
        }


        static void Main(string[] args)
        {            
            //设置允许不安全的HTTP2支持
            AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);

            var grpcConnect = provider.GetService<IGrpcConnect>();
            //认证
            //https://www.cnblogs.com/stulzq/p/11897628.html
            var token = "";
            var headers = new Metadata { { "Authorization", $"Bearer {token}" } };
            grpcConnect.SetMetadata(headers);


        label1:
            var client = provider.GetService<Greeter.GreeterClient>();
            var reply = client.SayHello(
                new HelloRequest { Name = "test" });
            Console.WriteLine("Greeter 服务返回数据: " + reply.Message);

            Console.ReadLine();
            goto label1;
        }
    }