Ocelot快速入门教程

Ocelot是什么

Ocelot是一个用.NET Core实现并且开源的API网关，就像一个公司的门卫承担着寻址、限制进入、安全检查、位置引导、等等功能。它的功能包括了：路由、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、Service Fabric、Skywalking等的集成。而且这些功能都只需要简单的配置即可完成。

Ocelot部署场景

一般而言，我们不会只部署一台网关服务器，那样太危险了。只要有一台挂了，就全完蛋了。为了实现高可用，我们会部署多台，当然在多台网关前，你还需要一台负载均衡器。Ocelot类型Nginx，内置了负载均衡器，但是他无法提供健康检查功能，服务注册也只能通过手动在配置文件里面添加完成。不够灵活。这个时候我们会采用Consul来做服务发现。Consul与Ocelot完美结合。

Ocelot配置说明

安装直接nuget上下载，再Add一下，这里就不说了。

{
  "ReRoutes": [
    {
      "DownstreamPathTemplate": "/api/Products/{everything}",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/Products/{everything}",
      "ServiceName": "ProductService",
      "UpstreamHttpMethod": [ "Get" ],
      "FileCacheOptions": { "TtlSeconds": 15 },
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      }
    },
    {
      "DownstreamPathTemplate": "/api/Products",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/Products",
      "ServiceName": "ProductService",
      "UpstreamHttpMethod": [ "Get" ],
      "FileCacheOptions": { "TtlSeconds": 15 },
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      }
    },

    {
      "DownstreamPathTemplate": "/api/Offer",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/Offers",
      "ServiceName": "PolicyService",
      "UpstreamHttpMethod": [ "Post" ],
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      },
      "AddHeadersToRequest": {
        "AgentLogin" : "Claims[http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier] > value[0] > |"
      }
    },

    {
      "DownstreamPathTemplate": "/api/Policy",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/Policies",
      "ServiceName": "PolicyService",
      "UpstreamHttpMethod": [ "Post" ],
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      }
    },

    {
      "DownstreamPathTemplate": "/api/Policy/{number}",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/Policies/{number}",
      "ServiceName": "PolicyService",
      "UpstreamHttpMethod": [ "Get" ],
      "FileCacheOptions": { "TtlSeconds": 15 },
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      }
    },

    {
      "DownstreamPathTemplate": "/api/PolicySearch",
      "DownstreamScheme": "http",
      "UpstreamPathTemplate": "/api/PolicySearch",
      "ServiceName": "PolicySearchService",
      "UpstreamHttpMethod": [ "Get" ],
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "ApiSecurity",
        "AllowedScopes": []
      },
      "RouteClaimsRequirement": {
        "userType" : "SALESMAN"
      }
    }
  ],
  "GlobalConfiguration": {
    "RequestIdKey": "OcRequestId",
    "AdministrationPath": "/administration",
    "UseServiceDiscovery" : true,
    "ServiceDiscoveryProvider": { "Type": "Eureka", "Host" : "localhost", "Port" : "8761"}
  }
}

两个根节点ReRoutes，GlobalConfiguration。

ReRoutes （告诉Ocelot如何处理上游请求）

【DownstreamPathTemplate】

下游路由模板，即真实处理请求的路径模板

【DownstreamScheme】

请求方式，http/https

【UpstreamPathTemplate】

上游请求的模板，即用户真实请求的链接

【UpstreamHttpMethod】

上游请求的http方法，是个数组，你可以写多个

【LoadBalancerOptions】

LeastConnection : 将请求发往最空闲的那个服务器

RoundRobin ：轮流发送

NoLoadBalance ：不启用负载均衡，总是发往第一个请求或者服务发现的那个服务器

【RateLimitOptions】

限流相关配置

GlobalConfiguration（顾名思义，全局配置）

包括了服务发现Eureka