ocelot网关启用动态路由
为了简化ocelot网关路由配置，可以考虑使用动态路由模式。下面是相关的英文介绍：
This feature was requested in issue 340. The idea is to enable dynamic routing when using a service discovery provider (see that section of the docs for more info). In this mode Ocelot will use the first segment of the upstream path to lookup the downstream service with the service discovery provider.
An example of this would be calling Ocelot with a url like https://api.mywebsite.com/product/products. Ocelot will take the first segment of the path which is product and use it as a key to look up the service in Consul. If Consul returns a service Ocelot will request it on whatever host and port comes back from Consul plus the remaining path segments in this case products thus making the downstream call http://hostfromconsul:portfromconsul/products. Ocelot will apprend any query string to the downstream url as normal.
In order to enable dynamic routing you need to have 0 Routes in your config. At the moment you cannot mix dynamic and configuration Routes. In addition to this you need to specify the Service Discovery provider details as outlined above and the downstream http/https scheme as DownstreamScheme.
In addition to that you can set RateLimitOptions, QoSOptions, LoadBalancerOptions and HttpHandlerOptions, DownstreamScheme (You might want to call Ocelot on https but talk to private services over http) that will be applied to all of the dynamic Routes.
翻译过来大概是说如果配合服务发现（例如consul），ocelot可以启用动态路由功能。例如：
访问http://api.hello.com/user/register这个gateway网址时，自动查询consul中是否有user服务，如果有（假设user服务的host为user.hello.com），则动态转发为http://user.hello.com/register。
要启用这个功能，只需要2个配置：
1、Routes、Reroutes只能是空节点，不能包含任何配置
2、在全局配置中设定DownstreamScheme，例如http
3、可以在全局配置中设定其他设定，例如RateLimitOptions、QoSOptions等
大概像下面：
{
"Routes": [],
"Aggregates": [],
"GlobalConfiguration": {
"RequestIdKey": null,
"ServiceDiscoveryProvider": {
"Host": "localhost",
"Port": 8500,
"Type": "Consul",
"Token": null,
"ConfigurationKey": null
},
"RateLimitOptions": {
"ClientIdHeader": "ClientId",
"QuotaExceededMessage": null,
"RateLimitCounterPrefix": "ocelot",
"DisableRateLimitHeaders": false,
"HttpStatusCode": 429
},
"QoSOptions": {
"ExceptionsAllowedBeforeBreaking": 0,
"DurationOfBreak": 0,
"TimeoutValue": 0
},
"BaseUrl": null,
"LoadBalancerOptions": {
"Type": "LeastConnection",
"Key": null,
"Expiry": 0
},
"DownstreamScheme": "http",
"HttpHandlerOptions": {
"AllowAutoRedirect": false,
"UseCookieContainer": false,
"UseTracing": false
}
}
}