- A+
所属分类：.NET技术
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.cer
openssl 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
#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging. FROM envoyproxy/envoy-dev:e834c24e061b710348ffd72016d5d1069698b4ff 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 base WORKDIR /app EXPOSE 16666 FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build WORKDIR /src COPY ["MyGateway/MyGateway.csproj", "MyGateway/"] COPY . . WORKDIR "/src/MyGateway" FROM build AS publish RUN dotnet publish "MyGateway.csproj" -c Release -o /app/publish FROM base AS final COPY ["server.crt","/usr/local/share/ca-certificates/"] RUN ["update-ca-certificates"] WORKDIR /app COPY --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:
通过docker-compsoe up -d 启动
通过postman调用，看到200状态码，终于成功了，最后试了下小程序也能通过这种方式调用后端GRPC了，整个人都舒服了...
