.net core 实现 api网关 进行 api版本控制

场景

  由一次大的项目改动引起的app端api不兼容问题,这时候就需要对api做版本控制了,权衡之后因为用户不多,选择了强更,没人想在已经写了8000行代码的单个svc文件中维护好几个版本的接口或者继续新建svc(wcf配置较繁琐),但暴露出的版本控制问题还是要解决的,不能每次都强更呀。

 

api版本控制方案

  分项目进行版本控制,一个项目一个版本号,维护两个版本号,分开部署,根据其版本号路由到对应host。

  根据当前项目情况,为了同时完成技术迭代(因没有code review,多次经手,wcf中基于http的api已经难以维护,并且使用的是.net fx4.0,各种不便,完全重构是不可能的),所以新版本采用restful web api(本来想直接上.net core web api,成本...)。

  关于api版本控制的其他几种方案不详述,网上很多文章,可以自己搜搜看,对比选用适合自己的方案。

       rest风格的api版本控制

此时需要将老的wcf 和新web api管理起来了,做一个api网关再合适不过 ,不仅处理了版本控制的问题,后面还可扩展网关的其他职能,迈开了从单体过渡到微服务的步伐

 

 

api网关方案:使用.net core web自实现(本来想使用Ocelot ,全套当然方便,因其版本控制基于url,我更倾向于rest基于http headers accept来控制,所以自己写吧)

 

api网关落地:

1.对服务的管理设计

  建了一个json文件来配置对服务的管理,因其要保留网关其他职能的可能性,所以设计时要注意其扩展性,当然目前没做服务发现,所以需要这么一个设计来管理服务。

  知道vnd啥意思吗?搜了半天才知道,自定义mime类型的前缀,当然在这里不是必须的,反正都是你自己约定解析的,当然对公还是遵循通用规范好一些。

  rule里面是对请求的验证规则,顺便使用polly做了重试和超时。

 1 {
 2   "Rule": {
 3     "CORS": {
 4       "AllowOrigins": "",
 5       "AllowMethods": "GET,POST,PUT,DELETE",
 6       "AllowHeaders": "Accept,Content-Type"
 7     },
 8     "Headers": {
 9       "AcceptPrefix": "vnd.saas.services.",
10       "AcceptKey": "version",
11       "AcceptContentType": "json"
12     },
13     "API": {
14       "FilterAPI": "",
15       "APITimeOut": "60"
16     }
17 
18   },
19   "Services": {
20     "main": {
21       "v1": {
22         "Host": "",
23         "Port": "",
24         "Deprecated": false
25       },
26       "v2": {
27         "Host": "",
28         "Port": "",
29         "Deprecated": false
30       }
31     }
32 
33   }
34 
35 }
services.json

2.构建中间件处理请求

  *注入IConfiguration和IHttpClientFactory,用来读取json配置和发送请求

  *解析请求中http headers 中accept属性,我这里就是通过分割字符串来解析,反正网上我是没找到解析accept中自定义mime类型的方法,然后与配置中的要求对比,拿到其路由信息

  *处理一些非法请求及错误

  *发送请求到该版本服务,正确返回后响应给请求者

  1 public class RequestMiddleware
  2     {
  3         private readonly RequestDelegate _next;
  4         private readonly IConfiguration _configuration;
  5         private readonly IHttpClientFactory _clientFactory;
  6 
  7         public RequestMiddleware(RequestDelegate next, IConfiguration configuration, IHttpClientFactory clientFactory)
  8         {
  9             _next = next;
 10             _configuration = configuration;
 11             _clientFactory = clientFactory;
 12         }
 13 
 14         public async Task InvokeAsync(HttpContext context)
 15         {
 16             var acceptStr = context.Request.Headers["Accept"]+"";
 17             var acceptPrefix= _configuration.GetSection("Rule:Headers:AcceptPrefix").Value;
 18             var acceptKey = _configuration.GetSection("Rule:Headers:AcceptKey").Value;
 19             var acceptContentType = _configuration.GetSection("Rule:Headers:AcceptContentType").Value;
 20             var filterAPI = _configuration.GetSection("Rule:API:FilterAPI").Value;
 21             var version = new ServiceVersion();
 22             var response = new HttpResponseMessage();
 23             var error_code = 0;
 24             var error_message = string.Empty;
 25 
 26             //default in now
 27             var accept = new Accept()
 28             {
 29                 ServiceName = "main",
 30                 Version = "v1",
 31                 AcceptContentType = "json"
 32             };
 33 
 34             if (!string.IsNullOrEmpty(acceptStr))
 35             {
 36                 var acceptArray = acceptStr.Split(';');
 37                 if (acceptArray.Length >= 2 && acceptArray[0].Contains(acceptPrefix) && acceptArray[1].Contains(acceptKey))
 38                 {
 39 
 40                     accept.ServiceName = acceptArray[0].Split('+')[0].Replace(acceptPrefix, "");
 41                     accept.AcceptContentType = acceptArray[0].Split('+')[1];
 42                     accept.Version = acceptArray[1].Split('=')[1];
 43                 }
 44                 
 45             }
 46 
 47             if (_configuration.GetSection($"Services:{accept.ServiceName}:{accept.Version}").Exists())
 48             {
 49                 _configuration.GetSection($"Services:{accept.ServiceName}:{accept.Version}").Bind(version);
 50             }
 51             else
 52             {
 53                 response.StatusCode= HttpStatusCode.BadRequest;
 54                 error_code = (int)HttpStatusCode.BadRequest;
 55                 error_message = "You should check that the request headers is correct";
 56             }
 57             if (version.Deprecated)
 58             {
 59                 response.StatusCode = HttpStatusCode.MovedPermanently;
 60                 error_code = (int)HttpStatusCode.MovedPermanently;
 61                 error_message = "You should check the version of the API";
 62             }
 63             
 64 
 65             try
 66             {
 67                 if (error_code == 0)
 68                 {
 69                     // filter api
 70                     var sourceName = context.Request.Path.Value.Split('/');
 71                     if (sourceName.Length > 1 && filterAPI.Contains(sourceName[sourceName.Length - 1]))
 72                         accept.ServiceName = "FilterAPI";
 73 
 74                     context.Request.Host = new HostString(version.Host, version.Port);
 75                     context.Request.PathBase = "";
 76 
 77                     var client = _clientFactory.CreateClient(accept.ServiceName);//rename to filter
 78                     var requestMessage = context.Request.ToHttpRequestMessage();
 79 
 80                     //var response = await Policy.NoOpAsync().ExecuteAsync(()=> {
 81                     //    return  client.SendAsync(requestMessage, context.RequestAborted); ;
 82                     //});
 83                     response = await client.SendAsync(requestMessage, context.RequestAborted);
 84                 }
 85             }
 86             catch (Exception ex)
 87             {
 88                 response.StatusCode= HttpStatusCode.InternalServerError;
 89                 error_code = (int)HttpStatusCode.InternalServerError;
 90                 error_message = "Internal Server Error";
 91 
 92             }
 93             finally
 94             {
 95                 if (error_code > 0) 
 96                 {
 97                     response.Headers.Clear();
 98                     response.Content = new StringContent("error is no content");
 99                     response.Headers.Add("error_code", error_code.ToString());
100                     response.Headers.Add("error_message", error_message);
101                 }
102                 await response.ToHttpResponse(context);
103             }
104             await _next(context);
105 
106         }
107     }
108 
109     // Extension method used to add the middleware to the HTTP request pipeline.
110     public static class RequestMiddlewareExtensions
111     {
112         public static IApplicationBuilder UseRequestMiddleware(this IApplicationBuilder builder)
113         {
114             return builder.UseMiddleware<RequestMiddleware>();
115         }
116     }
RequestMiddleware

 目前就构建了一个中间件,代码写得较乱

3.注册中间件和服务配置

  *在ConfigureServices中将services.json注册进去,这样中间件中才能读到

  *在Configure中使用中间件

 1 public void ConfigureServices(IServiceCollection services)
 2         {
 3             
 4             var configuration = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("Configs/services.json").Build();
 5             services.AddSingleton<IConfiguration>(c => configuration);
 6 
 7             var AllowOrigins =configuration.GetSection("Rule:CORS:AllowOrigins").Value.Split(',');
 8             var AllowMethods = configuration.GetSection("Rule:CORS:AllowMethods").Value.Split(',');
 9             var AllowHeaders = configuration.GetSection("Rule:CORS:AllowHeaders").Value.Split(',');
10 
11             services.AddCors(options => options.AddPolicy(
12                 "CORS", policy => policy.WithOrigins(AllowOrigins).WithHeaders(AllowHeaders).WithMethods(AllowMethods).AllowCredentials()
13                 ));
14 
15             var APITimeOut = int.Parse(configuration.GetSection("Rule:API:APITimeOut").Value);
16             var timeOutPolicy = Policy.TimeoutAsync<HttpResponseMessage>(APITimeOut);
17 
18             var retryPolicy = HttpPolicyExtensions.HandleTransientHttpError()
19             //.Or<{ExtensionsException}>()
20             .Or<TimeoutRejectedException>()
21             .WaitAndRetryAsync(new[]
22                 {
23                     TimeSpan.FromSeconds(1),
24                     TimeSpan.FromSeconds(3),
25                     TimeSpan.FromSeconds(6)
26                 });
27 
28             var policyWrap = Policy.WrapAsync(retryPolicy,timeOutPolicy);
29             foreach (var keyValuePair in configuration.GetSection("Services").GetChildren()) //configuration..AsEnumerable()
30             {
31                 //if (!keyValuePair.Key.Contains(':'))
32                     services.AddHttpClient(keyValuePair.Key).AddPolicyHandler(policyWrap); //SetHandlerLifetime(TimeSpan.FromMinutes(5)); default 2  .AddPolicyHandler(timeOutPolicy)
33             }
34         }
35 
36         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
37         public void Configure(IApplicationBuilder app, IHostingEnvironment env)
38         {
39             app.UseCors("CORS");
40             app.UseRequestMiddleware();
41         }
Startup

4.客户端对网关的使用设计

  *客户端需要自己设计如何管理它请求的服务与版本

 1 {
 2   "AcceptPrefix": "vnd.saas.services.",
 3   "AcceptKey": "version",
 4   "Main": {
 5     "ServiceName": "main",
 6     "LastVersion": "v1",
 7     "NewestVersion": "v2",
 8     "AcceptContentType": "json"
 9   }
10 
11 }
requestservices.json

 

到此,一个.net core实现的用来做api版本控制的简单网关就搭建好了,还有很多细节需要深入,还有很多功能需要扩展,初学.net core,欢迎指正讨论!

.net core 实现 api网关 进行 api版本控制

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