为了防止调用服务主动权在客户端，让客户端调 ， 调服务

影响：

1,重试策略（Retry）：当服务调用失败时，Polly 可以自动进行重试，这有助于 处理那些可能 由于暂时性 难题导致的服务不可用情况。 2、断路器（Circuit Breaker）：当检测到服务连续不可用时，断路器策略会介入， 快速返回错误响应，避免对下游服务的持续请求，从而预防服务雪崩现象。(熔断 ocelot+polly) polly:瞬态故障处理库 3、超时策略（Timeout）：为服务调用设置一个最大执行 时刻，超过这个 时刻的服 务调用将被认为失败，可以采取预设的应对措施。 4、舱壁隔离（Bulkhead Isolation）：通过限制对服务的并发调用数量，防止因 某个服务的 难题影响到整个 体系的稳定性。（ocelot 限流） 5、缓存策略（Cache）：提供一种机制，可以在服务调用的 结局不变的情况下直接 使用缓存 结局，减少不必要的服务调用。（ocelot 缓存） 6、降级策略（Fallback）：当服务调用失败时，可以提供一个备用的逻辑或者数 据作为响应， 进步用户体验。(polly 服务降级) 7、策略组合（PolicyWrap) : Polly 针对不同

1下载nuget包

<PackageReference Include="Ocelot" Version="23.1.0" /> <PackageReference Include="Ocelot.Provider.Consul" Version="23.1.0" /> <PackageReference Include="Ocelot.Provider.Polly" Version="23.1.0" />

2基本认识Ocelot.json文件

//// | | | | | | | | | | | | |*单地址*ַ | | | | | | | | | | | | | | | | //访问: http://localhost:9005/T9001/Users/All { "Routes": [ { "DownstreamPathTemplate": "/api/{url}", //服务地址,Url变量 "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "127.0.0.1", "Port": 9001 //服务端口 } //http://127.0.0.1:9001/api/users/all ], "UpstreamPathTemplate": "/T9001/{url}", // 地址: Url变量 "UpstreamHttpMethod": [ "Get", "Post" ] } ] } // | | | | | | | | | | | | | |*多地址 | | | | | | | | | | | | | | | | //访问: https://localhost:7253/T9001/Users/All //访问: https://localhost:7253/T9002/Users/All //访问: https://localhost:7253/T9003/Users/All { "Routes": [ { "DownstreamPathTemplate": "/api/{url}", //服务地址,Url变量 "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "127.0.0.1", "Port": 9001 //服务端口 } ], "UpstreamPathTemplate": "/T9001/{url}", // 地址: Url变量 "UpstreamHttpMethod": [ "Get", "Post" ] }, { "DownstreamPathTemplate": "/api/{url}", //服务地址,Url变量 "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "127.0.0.1", "Port": 9002 //服务端口 } ], "UpstreamPathTemplate": "/T9002/{url}", // 地址: Url变量 "UpstreamHttpMethod": [ "Get", "Post" ] }, { "DownstreamPathTemplate": "/api/{url}", //服务地址,Url变量 "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "127.0.0.1", "Port": 9003 //服务端口 } ], "UpstreamPathTemplate": "/T9003/{url}", // 地址: Url变量 "UpstreamHttpMethod": [ "Get", "Post" ] } ] } // | | | | | | | | | | | | | |*单地址多实例负载均衡 | | | | | | | | | | | | | | | | //可以负载均衡-- 然而不能动态伸缩服务, 因此一般不会使用他来做负载均衡, 需要和Consul做集成 { "Routes": [ { "DownstreamPathTemplate": "/api/{url}", //服务地址Url变量 "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "127.0.0.1", "Port": 9001 }, { "Host": "127.0.0.1", "Port": 9002 }, { "Host": "127.0.0.1", "Port": 9003 } //能负载均衡, 然而不能动态伸缩, 需要结合Consul来完成 ], "UpstreamPathTemplate": "/T/{url}", // 地址: Url变量 "UpstreamHttpMethod": [ "Get", "Post" ], "LoadBalancerOptions": { "Type": "RoundRobin" //轮询 // "LeastConnection" //最小连接数的服务器 "NoLoadBalance" //不负载均衡 // } //"LoadBalancerOptions": { // "Type": "CookieStickySessions", // "Key": "ASP.NET_SessionId", // "Expiry": 1800000 //} } ] }

完整文件，包含ocelot+consul+Polly+缓存

3使用Ocelot

{ "Routes": [ //这里注意一下版本（旧版本用ReRoutes） { "DownstreamPathTemplate": "/{controller}", "DownstreamScheme": "http", //下游方案 "UpstreamPathTemplate": "/TestGate/{controller}", "UpstreamHttpMethod": [ "Get", "Post" ], "UseServiceDiscovery": true,//使用服务发现 "ServiceName": "ConsulService", //请求服务名称 "LoadBalancerOptions": { "Type": "RoundRobin"//LeastConnection最少连接数的服务器，NoLoadBalance不负债均衡CookieStickySessions会话粘滞 }, "FileCacheOptions": { "TtlSeconds": 10, "Region": "myRegion" }, "RateLimitOptions": {//限流 "ClientWhitelist": ["Admin"],//白名单,在其中的不限流,请求头加上ClientId:Admin,区分 大致写 "EnableRateLimiting": true, "Period": "1m",//1s,1h "PeriodTimespan": 5,// 几许秒可以重试 "Limit": 4// 时刻段允许的最大请求数量 }, "QoSOptions": { "ExceptionsAllowedBeforeBreaking": 3,//允许3次异常polly "DurationOfBreak": 5000, //ms，熔断 时刻 "TimeoutValue": 2000//2s内不给响应，异常 时刻超过2s,熔断 } } ], "GlobalConfiguration": {//服务发现中心 "BaseUrl": "http://localhost:6001", //进行标头查找和替换以及某些管理配置 "ServiceDiscoveryProvider": { "Scheme": "http", "Host": "127.0.0.1", //你的Consul的ip地址 "Port": 8500, //你的Consul的端口 "Type": "Consul" //类型 }, "RateLimitOptions": {//限流响应 "QuotaExceededMessage": "Too Many Requests,please wait a moment", "HttpStatusCode": 503 } } } using Ocelot.DependencyInjection; using Ocelot.Middleware; using Ocelot.Provider.Consul; using Ocelot.Provider.Polly; var builder = WebApplication.CreateBuilder(args); // Add services to the container. builder.Services.AddControllers(); // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); builder.Services.AddOcelot().AddConsul().AddPolly();//注册 builder.Configuration.AddJsonFile("ocelot.json", false, true); var app = builder.Build(); // Configure the HTTP request pipeline. if (app.Environment.IsDevelopment()) { app.UseSwagger(); app.UseSwaggerUI(); } app.UseHttpsRedirection(); app.UseAuthorization(); app.MapControllers(); app.UseOcelot().Wait();//使用Ocelot app.Run();

4进阶

扩展自定义缓存

namespace LearnOcelot.OcelotExtend { public class CustomCacheExtend : IOcelotCache<CachedResponse> { private ILogger<CustomCacheExtend> _logger = null; public CustomCacheExtend(ILogger<CustomCacheExtend> logger) { this._logger = logger; } private static Dictionary<string, CacheDataModel> CustomCacheExtendDictionary = new Dictionary<string, CacheDataModel>(); /// <sum ry> /// 向缓存中去缓存数据--会调用这个 技巧 /// </sum ry> /// <param name="key"></param> /// <param name="value"></param> /// <param name="ttl"></param> /// <param name="region"></param> public void Add(string key, CachedResponse value, TimeSpan ttl, string region) { this._logger.LogWarning($"This is {nameof(CustomCacheExtend)}.{nameof(Add)}"); //CustomCacheExtendDictionary.Add(key, new CacheDataModel() //{ // CachedResponse = value, // Region = region, // Timeout = DateTime.Now.Add(ttl) //}); CustomCacheExtendDictionary[key] = new CacheDataModel() { CachedResponse = value, Region = region, Timeout = DateTime.Now.Add(ttl) }; } /// <sum ry> /// 添加缓存, 如果有历史缓存, 就覆盖 /// </sum ry> /// <param name="key"></param> /// <param name="value"></param> /// <param name="ttl"></param> /// <param name="region"></param> public void AddAndDelete(string key, CachedResponse value, TimeSpan ttl, string region) { this._logger.LogWarning($"This is {nameof(CustomCacheExtend)}.{nameof(AddAndDelete)}"); CustomCacheExtendDictionary[key] = new CacheDataModel() { CachedResponse = value, Region = region, Timeout = DateTime.Now.Add(ttl) }; } /// <sum ry> /// 清除缓存的数据 /// </sum ry> /// <param name="region"></param> public void ClearRegion(string region) { this._logger.LogWarning($"This is {nameof(CustomCacheExtend)}.{nameof(ClearRegion)}"); var keyList = CustomCacheExtendDictionary.Where(kv => kv.Value.Region.Equals(region)).Select(kv => kv.Key); foreach (var key in keyList) { CustomCacheExtendDictionary.Remove(key); } } public CachedResponse Get(string key, string region) { this._logger.LogWarning($"This is {nameof(CustomCacheExtend)}.{nameof(Get)}"); if (CustomCacheExtendDictionary.ContainsKey(key) && CustomCacheExtendDictionary[key] != null && CustomCacheExtendDictionary[key].Timeout > DateTime.Now && CustomCacheExtendDictionary[key].Region.Equals(region)) { return CustomCacheExtendDictionary[key].CachedResponse; } else return null; } } public class CacheDataModel { public CachedResponse CachedResponse { get; set; } public DateTime Timeout { get; set; } public string Region { get; set; } } }

 Program里添加

builder.Services.AddSingleton<IOcelotCache<CachedResponse>, CustomCacheExtend>();

AddandDelete和ClearRegion需要你自己调用，用于清除脏数据

Add 技巧在Get 技巧返回null调用。

扩展自定义轮询

public class CustomPollingLoadBalancer : ILoadBalancer { /// <sum ry> /// 通过注入的一段逻辑---就是在IOC注册的时候, 指定的策略的 制度 /// </sum ry> private readonly Func<Task<List<Service>>> _DownstreamServicesTaskList; /// <sum ry> /// 锁 /// </sum ry> private readonly object CustomPollingLoadBalancer_Lock = new object(); private int _lastIndex; //内部自己注册的ioc的 public CustomPollingLoadBalancer(Func<Task<List<Service>>> services) { this._DownstreamServicesTaskList = services; } /// <sum ry> /// 决定负载均衡的策略 /// </sum ry> /// <param name="httpContext"></param> /// <returns></returns> /// <exception cref="NotImplementedException"></exception> public async Task<Response<ServiceHostAndPort>> Lease(HttpContext httpContext) { ///downstreamServices: 服务列表 var downstreamServices = await this._DownstreamServicesTaskList(); lock (CustomPollingLoadBalancer_Lock) { Console.WriteLine($"This is {nameof(CustomPollingLoadBalancer)}.Lease"); Console.WriteLine($"This is {httpContext.Request.Host.Value}"); Console.WriteLine($"This is {string.Join(",", downstreamServices.Select(s => s.HostAndPort.DownstreamHost + s.HostAndPort.DownstreamPort))}"); if (_lastIndex >= downstreamServices.Count) { _lastIndex = 0; } var next = downstreamServices[_lastIndex]; _lastIndex++; return new OkResponse<ServiceHostAndPort>(next.HostAndPort); } } public void Release(ServiceHostAndPort hostAndPort) { } }

Program.cs里添加 

#region IOC扩展负载均衡策略 Func<IServiceProvider, DownstreamRoute, IServiceDiscoveryProvider, CustomPollingLoadBalancer> loadBalancerFactoryFunc = (serviceProvider, Route, serviceDiscoveryProvider) => new CustomPollingLoadBalancer(serviceDiscoveryProvider.Get); #endregion builder.Services.AddOcelot() //注意: nuget引入: Ocelot.Provider.Consul .AddConsul() //Ocelot注册到IOC容器 //扩展 Ocelot-缓存 //Nuet: Ocelot.Cache.CacheManager .AddCacheManager(x => { x.WithDictionaryHandle();//字典缓存 //如果我自己来扩展下, 可能会使用redis Mongo me ryCache }) .AddCustomLoadBalancer<CustomPollingLoadBalancer>(loadBalancerFactoryFunc); //配置生效自定义负载均衡策略