Ocelot网关

Ocelot是一个.net core框架下的网关的开源项目，下图是官方给出的基础实现图，即把后台的多个服务统一到网关处，前端应用：桌面端，web端，app端都只用访问网关即可。

Ocelot的实现原理就是把客户端对网关的请求(Request)，按照configuration.json的映射配置，转发给对应的后端http service，然后从后端http service获取响应(Response)后，再返回给客户端。当然有了网关后，我们可以在网关这层去做统一验证，也可以在网关处统一作监控。

接下来做个Demo

新建三个asp.net core web aip项目：

OcelotGateway网关项目，端口是5000

DemoAAPI项目A，端口是5001

DemoBAPI项目B，端口是5002

(注：端口可以在每个项目的Properties下的launchSettings.json中修改，发布后的端口可以在Program.cs中用UseUrls(“http://*:5000”)来修改)

对于OcelotGateway：

引用Ocelot的Nuget包：

视图->其他窗口->程序包管理控制台：Install-Package Ocelot

或项目右键“管理Nuget程序包”，在浏览里查找Ocelot进行安装

在OcelotGateway项目中添加一个configuration.json文件，关把它的属性“复制到输出目录”，设成“始终复制”，内容如下：

{

"ReRoutes": [

{

"DownstreamPathTemplate": "/demoaapi/values",

"DownstreamScheme": "http",

"DownstreamPort": 5001,

"DownstreamHost": "localhost",

"UpstreamPathTemplate": "/demoaapi/values",

"UpstreamHttpMethod": [ "Get" ],

"QoSOptions": {

"ExceptionsAllowedBeforeBreaking": 3,

"DurationOfBreak": 10,

"TimeoutValue": 5000

},

"HttpHandlerOptions": {

"AllowAutoRedirect": false,

"UseCookieContainer": false

},

"AuthenticationOptions": {

"AuthenticationProviderKey": "",

"AllowedScopes": []

}

},

{

"DownstreamPathTemplate": "/demobapi/values",

"DownstreamScheme": "http",

"DownstreamPort": 5002,

"DownstreamHost": "localhost",

"UpstreamPathTemplate": "/demobapi/values",

"UpstreamHttpMethod": [ "Get" ],

"QoSOptions": {

"ExceptionsAllowedBeforeBreaking": 3,

"DurationOfBreak": 10,

"TimeoutValue": 5000

},

"HttpHandlerOptions": {

"AllowAutoRedirect": false,

"UseCookieContainer": false

},

"AuthenticationOptions": {

"AuthenticationProviderKey": "",

"AllowedScopes": []

}

}

]

}

接下来对OcelotGateway的Program.cs进行改造

using Microsoft.AspNetCore.Hosting;

using Microsoft.Extensions.Configuration;

using Microsoft.Extensions.DependencyInjection;

namespace OcelotGateway

{

public class Program

{

public static void Main(string[] args)

{

BuildWebHost(args).Run();

}

public static IWebHost BuildWebHost(string[] args)

{

IWebHostBuilder builder = new WebHostBuilder();

//注入WebHostBuilder

return builder.ConfigureServices(service =>

{

service.AddSingleton(builder);

})

//加载configuration配置文人年

.ConfigureAppConfiguration(conbuilder =>

{

conbuilder.AddJsonFile("configuration.json");

})

.UseKestrel()

.UseUrls("http://*:5000")

.UseStartup<Startup>()

.Build();

}

}

}

同时，修改Startup.cs

using Microsoft.AspNetCore.Builder;

using Microsoft.AspNetCore.Hosting;

using Microsoft.Extensions.Configuration;

using Microsoft.Extensions.DependencyInjection;

using Ocelot.DependencyInjection;

using Ocelot.Middleware;

namespace OcelotGateway

{

public class Startup

{

public Startup(IConfiguration configuration)

{

Configuration = configuration;

}

public IConfiguration Configuration { get; }

public void ConfigureServices(IServiceCollection services)

{

//注入配置文件，AddOcelot要求参数是IConfigurationRoot类型，所以要作个转换

services.AddOcelot(Configuration as ConfigurationRoot);

}

public  void Configure(IApplicationBuilder app, IHostingEnvironment env)

{

//添加中间件

app.UseOcelot().Wait();

}

}

}

为了测试数据好看，我们把DemoAAPI项目和DemoBAPI项目的ValuesController作一下修改：

[Route("demoaapi/[controller]")]

public class ValuesController : Controller

{

[HttpGet]

public IEnumerable<string> Get()

{

return new string[] { "DemoA服务", "请求" };

}

……

}

[Route("demobapi/[controller]")]

public class ValuesController : Controller

{

[HttpGet]

public IEnumerable<string> Get()

{

return new string[] { "DemoB服务", "请求" };

}

……

}

最后在解决方案属性->多个启动项目中，把DemoAAPI，DemoBAPI，OcelotGateway都设成启动，开始启动解决方案，效果如下图