Services to generate relative route in runtime for specified cluster and path

[tvardero]

I have a simple scenario: during application startup I configure SwaggerUI to point to existing swagger docs in my downstream services. (No, I'm not using yarp-swagger nuget).

I add endpoints to my documents by calling o => o.SwaggerEndpoint(serviceDocUrl, serviceClusterId). serviceDocUrl and serviceClusterId I get by enumerating IProxyConfig.Clusters , filtering and collecting information. IProxyConfig I get from injected IProxyConfigProvider.

For time being I'm using Destination.Address + Destination.Metadata["SwaggerPath"], which gives me absolute route. Swagger will be used in Development (localhost) and multiple Staging (2 dev servers) environments, and not in Production. However I need to change it to use relative routes, because my downstream services won't be accessible from outside on Staging environments - they are in private network.

My config looks like this:

"ReverseProxy": {
  "Routes": {
    "todolistservice-route": {
      "ClusterId": "todolistservice-cluster",
      "Match": {
        "Path": "/todolistservice/{**catch-all}"
      },
      "Transforms": [
        {
          "PathRemovePrefix": "/todolistservice",
          "PathPrefix": "/api",
        }
      ]
    }
  },
  "Clusters": {
    "todolistservice-cluster": {
      "Destinations": {
        "todolistservice-destination-1": {
          "Address": "http://todolistservice:8080",
          "Metadata": {
            "SwaggerPath": "/swagger/v1/swagger.json"
          }
        }
      }
    }
  }
}

Problem is, I have to manually work with IProxyConfig, finding and mapping information, concatinating strings and supporting wildcard patterns recognition.

Is there any helper classes for generating relative URL to specified cluster+path? Like UrlHelper class from MVC?

[MihaZupan]

You might find RequestUtilities.MakeDestinationAddress helpful for the concat part.

Assuming you're trying to get the base Url based on the route match, I'm not sure there's something built-in that would go in reverse and generate a Url that would match a given route.
If you have a pattern of setting up routes in a similar way, you could consider looking for the PathRemovePrefix transform instead, maybe saving yourself from dealing with wildcards.

Re: IProxyConfigProvider, you might find using IProxyStateLookup easier (resolve it from DI) to look through routes/clusters.