Odtnhj

I have created a sample service fabric application in .NET Core and tried to register URLs in Kestrel but getting below error.
Kestrel no longer splits path and path base. A path base specified in UseUrls() will no longer work. To specify a path base, use the IApplicationBuilder.UsePathBase() extension method.

The serverUrl will be: http://localhost:8597/School/LOCAL

Below is the code in stateless services

public Task<string> OpenAsync(CancellationToken cancellationToken)
 
 var endpoint = FabricRuntime.GetActivationContext().GetEndpoint(this._endpointName);
 string serverUrl = $"endpoint.Protocol://FabricRuntime.GetNodeContext().IPAddressOrFQDN:endpoint.Port";

 // serverUrl = http://localhost:8597
 serverUrl = serverUrl + "/School/LOCAL/";

 webHost = new WebHostBuilder()
 .UseKestrel()
 .UseContentRoot(Directory.GetCurrentDirectory())
 .UseStartup<Startup>()
 .UseUrls(serverUrl)
 .Build();

 webHost.Start();

 return Task.FromResult(serverUrl);
 

So I have modified my code as below and tried to register my Url with IApplicationBuilder.UsePathBase(). However, I have observed below behavior.

http://localhost:8597/School/LOCAL/api/getstudentnames - Not Working
http://localhost:8597/api/getstudentnames - Working

Code Changes using UsePathBase

CommunicationListener.CS

 public Task<string> OpenAsync(CancellationToken cancellationToken)
 
 var endpoint = FabricRuntime.GetActivationContext().GetEndpoint(this._endpointName);
 string serverUrl = $"endpoint.Protocol://FabricRuntime.GetNodeContext().IPAddressOrFQDN:endpoint.Port";
 webHost = new WebHostBuilder()
 .UseKestrel()
 .UseContentRoot(Directory.GetCurrentDirectory())
 .UseStartup<Startup>()
 .UseUrls(serverUrl)
 .Build();

 webHost.Start();

 return Task.FromResult(serverUrl);
 

Startup.cs

 public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
 
 const string PathBase = "/School/LOCAL/";
 app.UsePathBase(PathBase);
 

I think this is working as expected.

AFAIK, the UsePathBase() feature has been added to remove the rootPath from the actual path received in the request for scenarios where the client request something via a reverse proxy that route requests based on VirtualPaths and the original URL must be rewritten in the service to understand it.

As Example:

• An API accept requests on http://<anyip>/users/123
  


• The API is exposed behind a proxy setup as a virtual directory like http://domain/api
  


• A client call http://domain/api/users/123
  


• The proxy receive the call as http://domain/api/users/123 and forward as is to the API that http://domain/users/123
  


• The API does not recognize the Url and return 404,

In this scenario, if you configure with UserPathBase("api") it will strip the api value from the URL to map to the route you had before.

An example is the one reported on this issue, as below:

 public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
 
 app.UsePathBase("/basepath");

 app.Map("/ping", map => map.Run(async 
 ctx => await ctx.Response.WriteAsync("pong")));

 app.UseMvc();
 

This will work for both urls below:

• /basepath/ping


• /ping

Because the basepath in the first will be removed and the API will always see second option.

This explain in more details, and this shows a issue similar to yours.

Another issue, is when the API return internal URLs, so for example, if had to generate the link to a user, without knowing it is behind a proxy, it would return http://<anyip>/users/123 where the right url should be http://<anyip>/api/users/123.

In summary, the API has to to the work that should be handled by the proxy, but some proxies is just a bridge and does not handle these cases.