我又造了个轮子：GrpcGateway-技术圈

我个人对GRPC是比较感兴趣的，最近在玩通过前端调用GRPC。通过前端调用GRPC业界有两种方式：GRPC Web和GRPC JSON转码。

GRPC Web

通过JS或者Blazor WASM调用GRPC，微软在这方面做的还是很好的，从.NET Core3.0之后就提供了两种实现GRPC Web的方式（Grpc.AspNetCore.Web与Envoy）。我在之前的一篇里也写过如何通过Blazor WASM调用GRPC Web。

GRPC JSON

通过Restful api调用一个代理服务，代理服务将数据转发到GRPC Server就是GRPC JSON。微软从.NET7开始也正式提供了GRPC JSON转码的方式。

为什么要造轮子

既然有了GRPC Web与GRPC Json，那我为啥还要再造这么一个轮子？

原因是有位同行看了如何通过Blazor WASM调用GRPC Web 这篇文章后，告诉我微信小程序目前没办法通过这种方式调用GRPC。我当时觉得很奇怪，微信小程序也属于前端，为啥不能调用GRPC呢？

GRPC Web+小程序遇到的问题

只是听说还不能确认，要自己试一试，于是我用GRPC Web的方式让小程序调用GRPC，首先需要生成GRPC JS Client代码：

protoc.exe -I=. test.proto --js_out=import_style=commonjs:.\grpcjs\ --plugin=protoc-gen-grpc=.\protoc-gen-grpc-web.exe --grpc-web_out=import_style=commonjs,mode=grpcwebtext:.\grpcjs\

然后将生成的代码引入小程序端，发现确实有问题，微信小程序编译后无法正常识别GRPC的namespace，会报以下错误：

proto is not defined

去查了下原因，应该是因为小程序目前不支持protobuf序列化。然后我通过一种取巧的方式手动在生成的GRPC JS中添加了proto变量

var proto = {}

再次尝试，虽然proto能找到，但是又找不到其他对象，并且最主要的是GRPC JS Client是通过proto工具生成的，每次生成手动定义proto变量也不现实。

GRPC Web+小程序遇到问题总结：

小程序目前不支持protobuf序列化
手动修改生成的GRPC JS Client不友好

既然小程序通过GRPC Web方式调用GRPC失败，那还有GRPC Json。

GRPC JSON+Envoy+小程序遇到的问题

我使用了Envoy来充当restful代理，调用GRPC。我在之前有一篇通过Envoy JSON代理GRPC的帖子。按这个帖子来了一遍。

计划通过docker-compose方式运行GRPC Server和Envoy代理。

既然用GRPC，那肯定用http2/http2，在docker里运行.net core必然需要证书，没有证书就自己搞一个自签证书。

openssl req -newkey rsa:2048 -nodes -keyout server.key -x509 -days 365 -out server.ceropenssl pkcs12 -export -in server.cer -inkey server.key -out server.pfx

证书有了，在GRPC里配置https

builder.WebHost.ConfigureKestrel(o =>{
    o.ListenAnyIP(1111, p =>    {        p.Protocols = HttpProtocols.Http2;        p.UseHttps("/app/server.pfx", "123456");    });});

然后就开始配置envoy

首先生成grpc proto描述符

protoc.exe -I=.  --descriptor_set_out=.\test.pb --include_imports .\test.proto  --proto_path=.

然后定义envoy配置文件

admin:  address:    socket_address: {address: 0.0.0.0, port_value: 9901}
static_resources:  listeners:  - name: listener1    address:      socket_address: {address: 0.0.0.0, port_value: 10000}    filter_chains:    - filters:      - name: envoy.filters.network.http_connection_manager        typed_config:          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager          stat_prefix: grpc_json          codec_type: AUTO          route_config:            name: local_route            virtual_hosts:            - name: local_service              domains: ["*"]              routes:              - match: {prefix: "/test"}                route:                  cluster: grpc          http_filters:          - name: envoy.filters.http.grpc_json_transcoder            typed_config:              "@type": type.googleapis.com/envoy.extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder              proto_descriptor: "/etc/envoy/test.pb"              services: ["test"]              print_options:                add_whitespace: true                always_print_primitive_fields: true                always_print_enums_as_ints: false                preserve_proto_field_names: false              auto_mapping: true          - name: envoy.filters.http.router            typed_config:             "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router  clusters:  - name: grpc    type: static    connect_timeout: 15s    lb_policy: ROUND_ROBIN    dns_lookup_family: V4_ONLY    typed_extension_protocol_options:      envoy.extensions.upstreams.http.v3.HttpProtocolOptions:        "@type": type.googleapis.com/envoy.extensions.upstreams.http.v3.HttpProtocolOptions        explicit_http_config:          http2_protocol_options: {}    load_assignment:      cluster_name: grpc      endpoints:      - lb_endpoints:        - endpoint:            address:              socket_address:                address: 某ip                port_value: 1111

下面就定义envoy的dockerfile，主要是信任自签证书

COPY ["server.crt","/usr/local/share/ca-certificates/"]RUN ["update-ca-certificates"]

最后就是定义docker-compsoe.yaml

version: '3.4'services:  myenvoy:    image: myenvoy    container_name: myenvoy    command: "-c /etc/envoy/envoy.yaml  --log-level debug"    build:      context: .      dockerfile: GrpcServer/DockerfileEnvoy    volumes:     - "grpcpbs/:/etc/envoy/"     - "grpcpbs/logs:/logs"    ports:      - "9901:9901"      - "10000:10000"    depends_on:      - grpcserver    networks:    - mynetwork  grpcserver:    image: grpcserver    container_name: grpcserver    networks:    - mynetwork    build:      context: .      dockerfile: GrpcServer/Dockerfile    ports:      - "1111:1111"networks:  mynetwork:

最后通过docker-compsoe up -d运行，但是postman调用的时候，envoy与grpcserver的通信连接成功了，但是数据传输时总是被 connection reset，去github上找原因也没找到。至此grpc json+envoy又失败了。

GRPC JSON+Envoy+小程序遇到问题总结：

数据传输时connection 被莫名reset

既然envoy走不通不行，那就自己造一个吧。

开始造轮子

GRPC JSON的形式，原理就是通过一个web api接收restful请求，将请求数据转发到GRPC Server。

首先创建一个web api命名为GrpcGateway，并引入proto文件，生成grpc client代码

  <ItemGroup>    <PackageReference Include="Google.Protobuf" Version="3.20.1" />    <PackageReference Include="Grpc.Net.Client" Version="2.46.0" />    <PackageReference Include="Grpc.Tools" Version="2.46.1">      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>      <PrivateAssets>all</PrivateAssets>    </PackageReference>    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />  </ItemGroup>  <ItemGroup>    <Protobuf Include="..\*.proto" GrpcServices="Client" />  </ItemGroup>

然后创建一个控制器去接受restful请求，而grpc client可采用反射来创建。

[ApiController][Route("[controller]")]    public class ProcessGrpcRequestController : ControllerBase{        private readonly ILogger<ProcessGrpcRequestController> _logger;        private readonly Func<string, ClientBase> _getGrpcClient;        public ProcessGrpcRequestController(ILogger<ProcessGrpcRequestController> logger, Func<string, ClientBase> getGrpcClient)    {        _logger = logger;        _getGrpcClient = getGrpcClient;    }        /// <summary>    /// 调用grpc        /// </summary>    /// <param name="serviceName">Grpc Service Name 从proto文件中查询</param>    /// <param name="method">Grpc Method Name 从proto文件中查询</param>    /// <returns></returns>    [HttpPost("serviceName/{serviceName}/method/{method}")]        public async Task<IActionResult> ProcessAsync(string serviceName, string method)    {            try        {                if (string.IsNullOrEmpty(serviceName))            {                    return BadRequest("serviceName不能为空");            }                if (string.IsNullOrEmpty(method))            {                    return BadRequest("method不能为空");            }                using var sr = new StreamReader(Request.Body, leaveOpen: true, encoding: Encoding.UTF8);                var paramJson = await sr.ReadToEndAsync();                if (string.IsNullOrEmpty(paramJson))            {                    return BadRequest("参数不能为空");            }                var client = _getGrpcClient(serviceName);                if (client == null)            {                    return NotFound();            }
            Type t = client.GetType();                var processMethod = t.GetMethods().Where(e => e.Name == method).FirstOrDefault();                if (processMethod == null)            {                    return NotFound();            }                var parameters = processMethod.GetParameters();                if (parameters == null)            {                    return NotFound();            }                var param = JsonConvert.DeserializeObject(paramJson, parameters[0].ParameterType);                if (param == null)            {                    return BadRequest("参数不能为空");            }                var pt = param.GetType();                var headers = new Metadata();                if (Request.Headers.Keys.Contains("Authorization"))            {                headers.Add("Authorization", Request.Headers["Authorization"]);            }                var result = processMethod.Invoke(client, new object[] { param, headers, null, null });                return Ok(result);        }            catch(Exception ex) when (        ex.InnerException !=null && ex.InnerException !=null && ex.InnerException is RpcException &&         ((ex.InnerException as RpcException).StatusCode == Grpc.Core.StatusCode.Unauthenticated ||         ((ex.InnerException as RpcException).StatusCode == Grpc.Core.StatusCode.PermissionDenied)))        {            _logger.LogError(ex, ex.ToString());                return Unauthorized();        }            catch (Exception ex)        {            _logger.LogError(ex, ex.Message);                return BadRequest(ex.ToString());        }

    }}

然后注入动态反射创建grpc client的方法

services.AddScoped(p => {    Func<string, ClientBase> func = serviceName =>    {                    var channel = GrpcChannel.ForAddress(grpcServerAddress);                    var parentClassName = $"{serviceName}";                    var assembly = Assembly.Load("你的dll名字");                    var parentType = assembly.GetType(parentClassName);                    var clientType=  parentType.GetNestedType($"{serviceName}Client");                    if (clientType == null)        {                        throw new Exception($"serviceName:{serviceName}不存在");        }                    var client = Activator.CreateInstance(clientType, new object[] { channel });                    return (ClientBase)client;    };                return func;});

然后定义grpc gateway dockerfile ，最主要需要信任证书

#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS baseWORKDIR /appEXPOSE 16666FROM mcr.microsoft.com/dotnet/sdk:6.0 AS buildWORKDIR /srcCOPY ["MyGateway/MyGateway.csproj", "MyGateway/"]COPY . .WORKDIR "/src/MyGateway"FROM build AS publishRUN dotnet publish "MyGateway.csproj" -c Release -o /app/publish
FROM base AS finalCOPY ["server.crt","/usr/local/share/ca-certificates/"]RUN ["update-ca-certificates"]WORKDIR /appCOPY --from=publish /app/publish .ENTRYPOINT ["dotnet", "MyGateway.dll"]

最后通过定义docker-compose

version: '3.4'services:  mygateway:    image: mygateway    container_name: mygateway    networks:    - mynetwork    build:      context: .      dockerfile: MyGateway/Dockerfile    ports:      - "2222:2222"  grpcserver:    image: grpcserver    container_name: grpcserver    networks:    - mynetwork    build:      context: .      dockerfile: GrpcServer/Dockerfile    ports:      - "1111:1111"networks:  mynetwork: