Dapr-服务调用

前言

　上一篇对Dapr进行了了解，并搭建了Dapr环境。接下来就对Dapr的各个构建块类型的了解、应用实际案例。

一、服务调用：

　在许多具有多个需要相互通信的服务的环境中，都会面临着很多问题。如：

维护其他服务的地址。
如何安全地调用服务。
在发生短暂的暂时性错误时如何处理重试。
分布式应用程序调用链路追踪。

　服务调用构建块通过使用 Dapr 挎斗作为服务的反向代理来解决这些难题。

　调用逻辑：

　服务调用就是应用程序可以使用 gRPC 或 HTTP 这样的标准协议来发现并可靠地与其他应用程序通信。

　Dapr的服务调用如何工作的总览图，如下：

服务 A 对服务 B 发起HTTP/gRPC的调用。
Dapr使用在给定主机平台上运行的名称解析组件发现服务B的位置。
Dapr 将消息转发至服务B的Dapr Sidecar

注: Dapr Sidecar 之间的所有调用考虑到性能都优先使用 gRPC。仅服务与 Dapr Sidecar之间的调用可以是 HTTP 或 gRPC
服务 B的 Dapr Sidecar 将请求转发至服务 B 上的特定端点 (或方法) 。服务 B 随后运行其业务逻辑代码。
服务 B 发送响应给服务 A。响应将转至服务 B 的Sidecar。
Dapr 将消息转发至服务 A 的 Dapr Sidecar。
服务 A 接收响应。

　服务调用特性：

　　由于调用经过Sidecar，Dapr 可以注入一些有其他行为：

失败时自动重试调用。
通过相互 (mTLS) 身份验证（包括自动证书滚动更新），在服务之间进行调用。
使用访问控制策略控制客户端可以执行的操作。
捕获服务间所有调用的跟踪和指标，以提供分布式调用链路追踪与诊断。

二、调用示例：

　1、创建两个项目：DaprFrontEnd（前端示例）、DaprBackEnd（后端示例）

　　DaprFrontEnd项目：Razor项目用于展示从后端示例中调用结果内容

　　DaprBackEnd项目：Api项目用于获取数据

　2、DaprFrontEnd项目调整运行：

　　a) 修改绑定端口：

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
            webBuilder.UseUrls("http://0.0.0.0:8220");
        });

　　b)使用Dapr cli 命令启动项目：

//dapr命令
dapr run --dapr-http-port 3511 --app-port 5000 --app-id backend dotnet  .DaprBackEnd.dl

//输出结果
Starting Dapr with id backend. HTTP Port: 3511. gRPC Port: 1030
time="2021-10-24T19:00:48.5801709+08:00" level=info msg="starting Dapr Runtime -- version 1.4.3 -- commit a8ee30180e1183e2a2e4d00c283448af6d73d0d0" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.5831673+08:00" level=info msg="log level set to: info" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.5890733+08:00" level=info msg="metrics server started on :1033/" app_id=backend instance=Coder scope=dapr.metrics type=log ver=1.4.3
time="2021-10-24T19:00:48.6178099+08:00" level=info msg="standalone mode configured" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.6178272+08:00" level=info msg="app id: backend" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.6205808+08:00" level=info msg="mTLS is disabled. Skipping certificate request and tls validation" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.6835042+08:00" level=info msg="local service entry announced: backend -> 192.168.0.109:1038" app_id=backend instance=Coder scope=dapr.contrib type=log ver=1.4.3
time="2021-10-24T19:00:48.6835042+08:00" level=info msg="Initialized name resolution to mdns" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.6855038+08:00" level=info msg="loading components" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7225025+08:00" level=info msg="component loaded. name: pubsub, type: pubsub.redis/v1" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7228271+08:00" level=info msg="waiting for all outstanding components to be processed" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7310234+08:00" level=info msg="component loaded. name: statestore, type: state.redis/v1" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.732082+08:00" level=info msg="all outstanding components processed" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7374914+08:00" level=info msg="enabled gRPC tracing middleware" app_id=backend instance=Coder scope=dapr.runtime.grpc.api type=log ver=1.4.3
time="2021-10-24T19:00:48.7384898+08:00" level=info msg="enabled gRPC metrics middleware" app_id=backend instance=Coder scope=dapr.runtime.grpc.api type=log ver=1.4.3
time="2021-10-24T19:00:48.7434866+08:00" level=info msg="API gRPC server is running on port 1030" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7444869+08:00" level=info msg="enabled metrics http middleware" app_id=backend instance=Coder scope=dapr.runtime.http type=log ver=1.4.3
time="2021-10-24T19:00:48.7444869+08:00" level=info msg="enabled tracing http middleware" app_id=backend instance=Coder scope=dapr.runtime.http type=log ver=1.4.3
time="2021-10-24T19:00:48.7464879+08:00" level=info msg="http server is running on port 3511" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7464879+08:00" level=info msg="The request body size parameter is: 4" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7474861+08:00" level=info msg="enabled gRPC tracing middleware" app_id=backend instance=Coder scope=dapr.runtime.grpc.internal type=log ver=1.4.3
time="2021-10-24T19:00:48.7474861+08:00" level=info msg="enabled gRPC metrics middleware" app_id=backend instance=Coder scope=dapr.runtime.grpc.internal type=log ver=1.4.3
time="2021-10-24T19:00:48.7484875+08:00" level=info msg="internal gRPC server is running on port 1038" app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:00:48.7494884+08:00" level=info msg="application protocol: http. waiting on port 5000.  This will block until the app is listening on that port." app_id=backend instance=Coder scope=dapr.runtime type=log ver=1.4.3
Updating metadata for app command: dotnet .DaprBackEnd.dll
You're up and running! Both Dapr and your app logs will appear here.

== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Now listening on: http://0.0.0.0:8220
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Application started. Press Ctrl+C to shut down.
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Hosting environment: Production
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Content root path: F:codingDaprMultiContainerDaprBackEndinDebug
etcoreapp3.1

　3、DaprBackEnd项目调整：

　　a) 修改端口

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
            webBuilder.UseUrls("http://0.0.0.0:8230");
        });

　　b) 添加Dapr.AspNetCore包

Install-Package Dapr.AspNetCore

　　c) 注入Dapr

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers().AddDapr();
    services.AddRazorPages();
}

　　d) 调用DaprBackEnd 服务接口：

public class IndexModel : PageModel
{
    private readonly DaprClient _daprClient;

    public IndexModel(DaprClient daprClient)
    {
        _daprClient = daprClient ?? throw new ArgumentNullException(nameof(daprClient));
    }

    public async Task OnGet()
    {
        //方式一：使用HttpClient
        //using var httpClient = DaprClient.CreateInvokeHttpClient();
        //var result = await httpClient.GetAsync("http://backend/WeatherForecast");
        //var resultContent = await result.Content.ReadAsStringAsync();

        //方式二：使用DaprClient
        var forecasts = await _daprClient.InvokeMethodAsync<IEnumerable<WeatherForecast>>(HttpMethod.Get, "backend", "weatherforecast");
        ViewData["WeatherForecastData"] = forecasts;

        //方式三：Grpc方式调用
        //var forecastsGrpc = await _daprClient.InvokeMethodGrpcAsync<IEnumerable<WeatherForecast>>("backend", "weatherforecast");
        //ViewData["WeatherForecastData"] = forecasts;
    }
}

　　e) 通过Dapr CLI启动DaprFrontEnd，指定sidecar端口为3501，默认为3500，指定app-port是8230，与DaprFrontEnd默认端口保持一致

//命令
dapr run --dapr-http-port 3501 --app-port 8230  --app-id frontend dotnet  .DaprFrontEnd.dll

//输出：
Starting Dapr with id frontend. HTTP Port: 3501. gRPC Port: 29840
time="2021-10-24T19:31:25.1254888+08:00" level=info msg="starting Dapr Runtime -- version 1.4.3 -- commit a8ee30180e1183e2a2e4d00c283448af6d73d0d0" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.1284879+08:00" level=info msg="log level set to: info" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.1294861+08:00" level=info msg="metrics server started on :29841/" app_id=frontend instance=Coder scope=dapr.metrics type=log ver=1.4.3
time="2021-10-24T19:31:25.1458074+08:00" level=info msg="standalone mode configured" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.1458074+08:00" level=info msg="app id: frontend" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.1463505+08:00" level=info msg="mTLS is disabled. Skipping certificate request and tls validation" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.1837081+08:00" level=info msg="local service entry announced: frontend -> 192.168.0.109:29845" app_id=frontend instance=Coder scope=dapr.contrib type=log ver=1.4.3
time="2021-10-24T19:31:25.1837081+08:00" level=info msg="Initialized name resolution to mdns" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.184711+08:00" level=info msg="loading components" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2316059+08:00" level=info msg="component loaded. name: pubsub, type: pubsub.redis/v1" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2316059+08:00" level=info msg="waiting for all outstanding components to be processed" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2419333+08:00" level=info msg="component loaded. name: statestore, type: state.redis/v1" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2423401+08:00" level=info msg="all outstanding components processed" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2434172+08:00" level=info msg="enabled gRPC tracing middleware" app_id=frontend instance=Coder scope=dapr.runtime.grpc.api type=log ver=1.4.3
time="2021-10-24T19:31:25.2434172+08:00" level=info msg="enabled gRPC metrics middleware" app_id=frontend instance=Coder scope=dapr.runtime.grpc.api type=log ver=1.4.3
time="2021-10-24T19:31:25.2439954+08:00" level=info msg="API gRPC server is running on port 29840" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2439954+08:00" level=info msg="enabled metrics http middleware" app_id=frontend instance=Coder scope=dapr.runtime.http type=log ver=1.4.3
time="2021-10-24T19:31:25.2445399+08:00" level=info msg="enabled tracing http middleware" app_id=frontend instance=Coder scope=dapr.runtime.http type=log ver=1.4.3
time="2021-10-24T19:31:25.2450858+08:00" level=info msg="http server is running on port 3501" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2450858+08:00" level=info msg="The request body size parameter is: 4" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2456242+08:00" level=info msg="enabled gRPC tracing middleware" app_id=frontend instance=Coder scope=dapr.runtime.grpc.internal type=log ver=1.4.3
time="2021-10-24T19:31:25.2461714+08:00" level=info msg="enabled gRPC metrics middleware" app_id=frontend instance=Coder scope=dapr.runtime.grpc.internal type=log ver=1.4.3
time="2021-10-24T19:31:25.2467123+08:00" level=info msg="internal gRPC server is running on port 29845" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:25.2478066+08:00" level=info msg="application protocol: http. waiting on port 8230.  This will block until the app is listening on that port." app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
Updating metadata for app command: dotnet .DaprFrontEnd.dll
You're up and running! Both Dapr and your app logs will appear here.

== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Now listening on: http://0.0.0.0:8230
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Application started. Press Ctrl+C to shut down.
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Hosting environment: Production
== APP == info: Microsoft.Hosting.Lifetime[0]
== APP ==       Content root path: F:codingDaprMultiContainerDaprFrontEndinDebug
etcoreapp3.1
time="2021-10-24T19:31:26.10297+08:00" level=info msg="application discovered on port 8230" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:26.2373056+08:00" level=info msg="application configuration loaded" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:26.2422307+08:00" level=info msg="actor runtime started. actor idle timeout: 1h0m0s. actor scan interval: 30s" app_id=frontend instance=Coder scope=dapr.runtime.actor type=log ver=1.4.3
time="2021-10-24T19:31:26.2677804+08:00" level=info msg="dapr initialized. Status: Running. Init Elapsed 1121.4194ms" app_id=frontend instance=Coder scope=dapr.runtime type=log ver=1.4.3
time="2021-10-24T19:31:26.5035983+08:00" level=info msg="placement tables updated, version: 0" app_id=frontend instance=Coder scope=dapr.runtime.actor.internal.placement type=log ver=1.4.3

　　查看dapr运行应用情况：

dapr list
  APP ID    HTTP PORT  GRPC PORT  APP PORT  COMMAND               AGE  CREATED              PID
  backend   3511       1030       5000      dotnet .DaprBack...  32m  2021-10-24 19:00.47  4900
  frontend  3501       29840      8230      dotnet .DaprFron...  1m   2021-10-24 19:31.24  20856

　4、dapr cli 调用方式：

dapr invoke --app-id backend --verb "GET" --method weatherforecast

三、Dapr扩展功能：

　1、链路跟踪查看：自承载的方式下，Dapr默认启动了zipkin容器，可以通过以下链接查看： http://localhost:9411/zipkin/

　2、Dapr Dashboard：

　　a) 启动 Dapr Dashboard：

dapr dashboard

　　b) 查看页面：http://localhost:8080/

总结：

　本篇对构建块中服务调用进行了解，并在.NET Core 程序中进行了验证。　　　