How to handle non-root gateway?

I have a question regarding the handling of swagger generation when the Ocelot gateway endpoint is not on root. Using the following ocelot.json:

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/v1/settings/{everything}",
      "DownstreamScheme": "http",
      "ServiceName": "backendpreferences",
      "UpstreamPathTemplate": "/api/v1/settings/{everything}",
      "UpstreamHttpMethod": [ "Get", "Post", "Put", "Delete" ],
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "Bearer",
        "AllowedScopes": []
      },
      "SwaggerKey": "settings"
    }
  ],
  "SwaggerEndPoints": [
    {
      "Key": "settings",
      "TransformByOcelotConfig": true,
      "Config": [
        {
          "Name": "My Settings API",
          "Version": "v1",
          "Service": {
            "Name": "backendpreferences",
            "Path": "/swagger/v1/swagger.json"
          }
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "https://myapi.com/mygateway",
    "RequestIdKey": "OcRequestId",
    "AdministrationPath": "/administration",
    "UseServiceDiscovery": true,
    "ServiceDiscoveryProvider": {
      "Host": "consul",
      "Port": 8500,
      "Type": "Consul"
    }
  }

In code the SwaggerForOcelot setup is very basic:

app.UseSwaggerForOcelotUI(opt =>
{
    opt.PathToSwaggerGenerator = "/swagger/docs";
});

Ocelot itself works fine with this setup.

However, whenever we open the swagger documentation at https://myapi.com/mygateway/swagger/index.html the page starts loading but it tries to load the subdocuments at https://myapi.com/swagger/docs rather than the expected https://myapi.com/mygateway/swagger/docs. This causes the page to not load fully and show a fetch error.

Is there a way to set the base url which SwaggerForOcelot should use for the gateway (or how to make it use the Ocelot baseUrl)?

We’ve tried something like opt.DownstreamSwaggerEndPointBasePath = "../swagger/docs"; as suggested in issue #113, and while this solved the loading of documents, it doesn’t fix the urls in the generated document itself. Those still go for the root and therefore the calls fail with a 404:

[leonluc-dev]

We had set the base path in ocelot.json. But adding it in code using UsePathBase seems to have solved the issue.

[liamharper2453]

@alex-tselikovsky None of the above worked for me.

Had to do something like:

    private string AlterUpstreamSwaggerJson(HttpContext context, string swaggerJson)
    {
        swaggerJson = swaggerJson.Replace("\"/v", "\"/api-gateway/v");
        var swagger = JObject.Parse(swaggerJson);
        return swagger.ToString(Formatting.Indented);
    }

    app.UseSwaggerForOcelotUI(opt =>
    {
      opt.ReConfigureUpstreamSwaggerJson = env.IsDevelopment() ? default : AlterUpstreamSwaggerJson;
      opt.DownstreamSwaggerEndPointBasePath = "../swagger/docs";
    });