How to set BaseUrl for Swagger in ASP.NET Core Web API using NSwag.AspNetCore (when hosted behind a reverse proxy)

user_7523752 0
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I am struggling with the following situation:

I have an ASP.NET Core Web API with the following Swagger configuration in Startup.cs:

    public void ConfigureServices(IServiceCollection services)
    {
      ...

      services.AddSwaggerDocument(config =>
      {
        config.PostProcess = document =>
        {
          document.Info.Version = "v1";
          document.Info.Title = "...";
        };
      });

      ...
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
      ...

      app.UseOpenApi();
      app.UseSwaggerUi3();

      ...
    }

If I run the api locally everything works fine. Means I can access the Swagger page at http://localhost:5000/swagger/index.html and execute requests from there against the api which is available at http://localhost:5000/api.

On production, my api is running inside a Docker container and behind a reverse proxy. The container exposes the Swagger page at http://localhost:5000/swagger/index.html and the reverse proxy maps external requests to https://my.domain.com to http://localhost:5000 internally. This way I am actually able to access the Swagger page at http://my.domain.com/swagger/index.html. So far everything is fine.

The issue is when I want to execute reqests against my api from that production Swagger page. I see in the network tab of the browser dev tools that Swagger still sends the requests to http://localhost:5000/api what of course does not work. Instead it should send the requests to https://my.domain.com/api. Also below the title, the Swagger page states [ Base URL: localhost:5000 ].

I am not able to figure out how I could configure Swagger to use whatever base url I provide (like https://my.domain.com/ in my current case) so that I could execute requests against the api from anywhere and also that the BaseUrl below the title would be correct.

Can anybody help me here?

nswag swagger asp.net-core c#
1 Answers

Figured it out myself meanwhile. The solution is to remove the localhost server (which is added by ASP.NET Core middleware) and to add my own one like this:

app.UseOpenApi(settings =>
{
  settings.PostProcess = (document, httpRequest) =>
  {
    document.Servers.Clear();
    document.Servers.Add(new OpenApiServer { Url = "..." });
  };
});

This Issue/Comment directed me in the right direction: https://github.com/RicoSuter/NSwag/issues/2441#issuecomment-583721522

user_75237520
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