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.NET Core 下的 API 网关

.NET Core 下的 API 网关

网关介绍

网关其实就是将我们写好的API全部放在一个统一的地址暴露在公网,提供访问的一个入口。在 .NET Core下可以使用Ocelot来帮助我们很方便的接入API 网关。与之类似的库还有ProxyKit,微软也发布了一个反向代理的库YARP

关于网关的介绍不多说了,网上文章也挺多的,这些都是不错的选择,听说后期Ocelot将会使用YARP来重写。本篇主要实践一下在.NET Core环境下使用Ocelot

接入使用

接口示例

先创建几个项目用于测试,创建两个默认的API项目,Api_A和Api_B,在创建一个网关项目Api_Gateway,网关项目可以选择空的模板。

现在分别在Api_A和Api_B中写几个api,将默认的WeatherForecastController中返回模型WeatherForecast添加一个字段Source,用于区分是哪个API返回的数据。

using System;  namespace Api_A {     public class WeatherForecast     {         public string Source { get; set; } = "Api_A";          public DateTime Date { get; set; }          public int TemperatureC { get; set; }          public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);          public string Summary { get; set; }     } }  using System;  namespace Api_B {     public class WeatherForecast     {         public string Source { get; set; } = "Api_B";          public DateTime Date { get; set; }          public int TemperatureC { get; set; }          public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);          public string Summary { get; set; }     } } 

直接使用WeatherForecastController默认方法,在路由中添加api前缀。

using Microsoft.AspNetCore.Mvc; using System; using System.Collections.Generic; using System.Linq;  namespace Api_A.Controllers {     [ApiController]     [Route("api/[controller]")]     public class WeatherForecastController : ControllerBase     {         private static readonly string[] Summaries = new[]         {             "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"         };          [HttpGet]         public IEnumerable<WeatherForecast> Get()         {             var rng = new Random();             return Enumerable.Range(1, 5).Select(index => new WeatherForecast             {                 Date = DateTime.Now.AddDays(index),                 TemperatureC = rng.Next(-20, 55),                 Summary = Summaries[rng.Next(Summaries.Length)]             }).ToArray();         }     } }  using Microsoft.AspNetCore.Mvc; using System; using System.Collections.Generic; using System.Linq;  namespace Api_B.Controllers {     [ApiController]     [Route("api/[controller]")]     public class WeatherForecastController : ControllerBase     {         private static readonly string[] Summaries = new[]         {             "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"         };          [HttpGet]         public IEnumerable<WeatherForecast> Get()         {             var rng = new Random();             return Enumerable.Range(1, 5).Select(index => new WeatherForecast             {                 Date = DateTime.Now.AddDays(index),                 TemperatureC = rng.Next(-20, 55),                 Summary = Summaries[rng.Next(Summaries.Length)]             }).ToArray();         }     } } 

再分别在Api_A和Api_B中添加两个控制器:ApiAController、ApiBController,然后加上几个简单的restful api。

using Microsoft.AspNetCore.Mvc; using System.Collections.Generic;  namespace Api_A.Controllers {     [Route("api/[controller]")]     [ApiController]     public class ApiAController : ControllerBase     {         [HttpGet]         public IEnumerable<string> Get()         {             return new string[] { "value1", "value2" };         }          [HttpGet("{id}")]         public string Get(int id)         {             return $"Get:{id}";         }          [HttpPost]         public string Post([FromForm] string value)         {             return $"Post:{value}";         }          [HttpPut("{id}")]         public string Put(int id, [FromForm] string value)         {             return $"Put:{id}:{value}";         }          [HttpDelete("{id}")]         public string Delete(int id)         {             return $"Delete:{id}";         }     } } 
using Microsoft.AspNetCore.Mvc; using System.Collections.Generic;  namespace Api_B.Controllers {     [Route("api/[controller]")]     [ApiController]     public class ApiBController : ControllerBase     {         [HttpGet]         public IEnumerable<string> Get()         {             return new string[] { "value1", "value2" };         }          [HttpGet("{id}")]         public string Get(int id)         {             return $"Get:{id}";         }          [HttpPost]         public string Post([FromForm] string value)         {             return $"Post:{value}";         }          [HttpPut("{id}")]         public string Put(int id, [FromForm] string value)         {             return $"Put:{id}:{value}";         }          [HttpDelete("{id}")]         public string Delete(int id)         {             return $"Delete:{id}";         }     } } 

.NET Core 下的 API 网关

.NET Core 下的 API 网关

方便查看接口,这里添加一下swagger组件,这样我们Api_A和Api_B项目分别就有了6个接口。

接着打包docker镜像,放在docker中运行这两个api项目。这一步可以用任何你熟悉的方式,run起来即可。

docker build -t api_a:dev -f ./Api_A/Dockerfile . docker build -t api_b:dev -f ./Api_B/Dockerfile . 

build成功后,指定两个端口运行api项目。

docker run -d -p 5050:80 --name api_a api_a:dev docker run -d -p 5051:80 --name api_b api_b:dev 

Api_A指定了5050端口,通过 http://localhost:5050/swagger打开可以看到swagger文档界面,Api_B指定了5051端口,通过 http://localhost:5051/swagger打开可以看到swagger文档界面,这样就大功告成了,接下来才是重点将两个api项目配置到Api_Gateway网关项目中。

配置网关

在网关项目Api_Gateway中都添加Ocelot组件包。

Install-Package Ocelot 

Ocelot中最关键的就是配置路由信息,新建一个ocelot.json配置文件,将我们的两个API接口匹配规则放进去。

{   "Routes": [     //ApiA     {       "DownstreamPathTemplate": "/api/WeatherForecast",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5050         }       ],       "UpstreamPathTemplate": "/ApiA/WeatherForecast",       "UpstreamHttpMethod": [ "Get" ]     },     {       "DownstreamPathTemplate": "/api/ApiA",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5050         }       ],       "UpstreamPathTemplate": "/ApiA",       "UpstreamHttpMethod": [ "Get", "POST" ]     },     {       "DownstreamPathTemplate": "/api/ApiA/{id}",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5050         }       ],       "UpstreamPathTemplate": "/ApiA/{id}",       "UpstreamHttpMethod": [ "Get", "Put", "Delete" ]     },     //ApiB     {       "DownstreamPathTemplate": "/api/WeatherForecast",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5051         }       ],       "UpstreamPathTemplate": "/ApiB/WeatherForecast",       "UpstreamHttpMethod": [ "Get" ]     },     {       "DownstreamPathTemplate": "/api/ApiB",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5051         }       ],       "UpstreamPathTemplate": "/ApiB",       "UpstreamHttpMethod": [ "Get", "POST" ]     },     {       "DownstreamPathTemplate": "/api/ApiB/{id}",       "DownstreamScheme": "http",       "DownstreamHostAndPorts": [         {           "Host": "localhost",           "Port": 5051         }       ],       "UpstreamPathTemplate": "/ApiB/{id}",       "UpstreamHttpMethod": [ "Get", "Put", "Delete" ]     }   ],   "GlobalConfiguration": {     "BaseUrl": "https://localhost:44335"   } } 

关于配置文件中的各项具体含义,可以参考官方文档中的介绍。主要就是将DownstreamPathTemplate模板内容转换为UpstreamPathTemplate模板内容进行接口的访问,同时可以指定HTTP请求的方式等等。GlobalConfiguration中的BaseUrl为我们暴漏出去的网关地址。

设置好ocelot.json后,需要在代码中使用它,在Program.cs中添加配置文件。

using Microsoft.AspNetCore.Hosting; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.Hosting;  namespace Api_Gateway {     public class Program     {         public static void Main(string[] args)         {             CreateHostBuilder(args).Build().Run();         }          public static IHostBuilder CreateHostBuilder(string[] args) =>             Host.CreateDefaultBuilder(args)                 .ConfigureAppConfiguration((context, config) =>                 {                     config.AddJsonFile("ocelot.json", optional: false, reloadOnChange: true);                 })                 .ConfigureWebHostDefaults(webBuilder =>                 {                     webBuilder.UseStartup<Startup>();                 });     } } 

Startup.cs中使用Ocelot

using Microsoft.AspNetCore.Builder; using Microsoft.AspNetCore.Hosting; using Microsoft.AspNetCore.Http; using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.Hosting; using Ocelot.DependencyInjection; using Ocelot.Middleware;  namespace Api_Gateway {     public class Startup     {         public void ConfigureServices(IServiceCollection services)         {             services.AddOcelot();         }          public void Configure(IApplicationBuilder app, IWebHostEnvironment env)         {             if (env.IsDevelopment())             {                 app.UseDeveloperExceptionPage();             }              app.UseRouting();              app.UseEndpoints(endpoints =>             {                 endpoints.MapGet("/", async context =>                 {                     await context.Response.WriteAsync("Hello World!");                 });             });              app.UseOcelot().Wait();         }     } } 

完成以上操作后,我们试着去调用接口看看能否正确获取预期数据。

curl -X GET "https://localhost:44335/ApiA" curl -X GET "https://localhost:44335/ApiB"  curl -X POST "https://localhost:44335/ApiA" -H "Content-Type: multipart/form-data" -F "value=ApiA" curl -X POST "https://localhost:44335/ApiB" -H "Content-Type: multipart/form-data" -F "value=ApiB"  curl -X GET "https://localhost:44335/ApiA/12345" curl -X GET "https://localhost:44335/ApiB/12345"  curl -X PUT "https://localhost:44335/ApiA/12345" -H "Content-Type: multipart/form-data" -F "value=ApiA" curl -X PUT "https://localhost:44335/ApiB/12345" -H "Content-Type: multipart/form-data" -F "value=ApiB"  curl -X DELETE "https://localhost:44335/ApiA/12345" curl -X DELETE "https://localhost:44335/ApiB/12345"  curl -X GET "https://localhost:44335/ApiA/WeatherForecast" curl -X GET "https://localhost:44335/ApiB/WeatherForecast" 

.NET Core 下的 API 网关

可以看到,两个项目中的接口全部可以通过网关项目暴露的地址进行中转,是不是很方便?

本篇只是简单的应用,对于Ocelot的功能远不止于此,它非常强大,还可以实现请求聚合、服务发现、认证、鉴权、限流熔断、并内置了负载均衡器,而且这些功能都是只需要简单的配置即可完成。就不一一描述了,如有实际开发需求和问题,可以查看官方文档和示例。

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