How to handle non-root gateway?

[leonluc-dev]

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:

[Burgyn]

Hi,

Do you have a base url set in Configure method? app.UsePathBase("/mygateway");

Minimal working example:

Ocelot.json

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/v1/settings/{everything}",
      "UpstreamPathTemplate": "/api/v1/settings/{everything}",
      "SwaggerKey": "settings"
    }
  ],
  "SwaggerEndPoints": [
    {
      "Key": "settings",
      "Config": [
        {
          "Name": "My Settings API",
          "Version": "v1",
          "Url": "http://localhost:5100/swagger/v1/swagger.json"
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:5000/mygateway"
  }

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddOcelot();

    services.AddSwaggerForOcelot(Configuration);
    services.AddControllers();
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UsePathBase("/mygateway");
    app.UseSwaggerForOcelotUI()
        .UseOcelot()
        .Wait();
}

[leonluc-dev]

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

[alex-tselikovsky]

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

Hello. Did it solve your problem?
I have the same issue. But if I set app.UsePathBase("/basepath"); it doesn't help me.
I get request without changes

{
"Routes": [
{
"DownstreamPathTemplate": "/api/{everything}",
"DownstreamScheme": "http",
"DownstreamHostAndPorts": [
{
"Host": "localhost",
"Port": 10002
}
],
"UpstreamPathTemplate": "/api/v1/location/{everything}",
"UpstreamHttpMethod": [ "Get" ],
"SwaggerKey": "location",
"VirtualDirectory":"/some"
}
],
"SwaggerEndPoints": [
{
"Key": "location",
"Config": [
{
"Name": "Location API",
"Version": "v1",
"Url": "http://localhost:10002/swagger/v1/swagger.json"
}
]
}],
"GlobalConfiguration": {
"BaseUrl": "http://localhost:5000/basepath"
}
}
Whan could be the problem? Thanks

[BernhardJ]

Hi
If I'm not completly wrong, this could be the same issue, like I had. But my solution was different.
See #243
Both, the ocelot gateway and the downstream service are not in the root directory.
I hope this could help.

[alex-tselikovsky]

Hi If I'm not completly wrong, this could be the same issue, like I had. But my solution was different. See #243 Both, the ocelot gateway and the downstream service are not in the root directory. I hope this could help.

Thanks for your answer. Do you have correct urls in your swagger.json for downstream service? My urls don't have prefix "basepath".
For example I need "basepath/api/v1/location/Areas", but it get me only "/api/v1/location/Areas".

[BernhardJ]

Hi If I'm not completly wrong, this could be the same issue, like I had. But my solution was different. See #243 Both, the ocelot gateway and the downstream service are not in the root directory. I hope this could help.

Thanks for your answer. Do you have correct urls in your swagger.json for downstream service? My urls don't have prefix "basepath". For example I need "basepath/api/v1/location/Areas", but it get me only "/api/v1/location/Areas".

The 'basepath' is called 'testpath' in my sample for the downstream service.
The virtual directory / application directory of the downstream api is testpath.
I do not set the app.UsePathBase("/testpath") in my code

The virtual directory / application directory of the ocelot gateway is 'ocelotpath' in my sample.

    <PackageReference Include="MMLib.SwaggerForOcelot" Version="6.1.0" />
    <PackageReference Include="Ocelot" Version="18.0.0" />

[alex-tselikovsky]

@Burgyn Hi, I tried your minimal example, but I didn't have correct urls for downstream services. For example for instead of "mygateway/api/Books", I get just "/api/Books" without mygateway.

ocelot.js

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/{everything}",
      "UpstreamPathTemplate": "/api/{everything}",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 7237
        }
      ],
      "SwaggerKey": "settings"
    }
  ],
  "SwaggerEndPoints": [
    {
      "Key": "settings",
      "Config": [
        {
          "Name": "My Settings API",
          "Version": "v1",
          "Url": "https://localhost:7237/swagger/v1/swagger.json"
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "http://localhost:7173/mygateway/"
  }
}

Program.cs

using Ocelot.DependencyInjection;
using Ocelot.Middleware;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOcelot();
builder.Configuration.SetBasePath(builder.Environment.ContentRootPath)
  .AddJsonFile("ocelot.json", optional: false)
  .AddEnvironmentVariables();
builder.Services.AddSwaggerForOcelot(builder.Configuration);
builder.Services.AddControllers();
var app = builder.Build();

app.UsePathBase("/mygateway");
app.UseSwaggerForOcelotUI(opt =>
  {
    opt.DownstreamSwaggerEndPointBasePath = "/mygateway/swagger/docs";
  })
  .UseOcelot()
  .Wait();

app.Run();

[alex-tselikovsky]

@leonluc-dev did you solve your problem?

[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";
    });

[MatheusXavier]

I have the following scenario:

My API Gateways run, within a path of my subdomain:

• https://mydomain.com/staging/mobileapigw
• https://mydomain.com/staging/webapigw
• https://mydomain.com/devlopment/mobileapigw
• https://mydomain.com/devlopment/webapigw

My configuration file is very simple:

{
  "Routes": [
    {
      "SwaggerKey": "deviceapi",
      "UpstreamPathTemplate": "/api/{version}/rooms",
      "UpstreamHttpMethod": [
        "POST",
        "OPTIONS"
      ],
      "DownstreamPathTemplate": "/api/{version}/rooms",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "device-api",
          "Port": 80
        }
      ]
    }
  ],
  "GlobalConfiguration": {
    "RequestIdKey": "OcRequestId",
    "AdministrationPath": "/administration"
  },
  "SwaggerEndPoints": [
    {
      "Key": "deviceapi",
      "Config": [
        {
          "Name": "Device API",
          "Version": "v1",
          "Url": "http://device-api:80/swagger/v1/swagger.json"
        }
      ]
    }
  ]
}

And I was facing the same problem reported in this issue, I tried the solutions that were reported:

1. Using app.UsePathBase("/mygateway");
2. Solution reported on Configure SwaggerForOcelot running in a subpath (IIS application) #243

I wasn't successful with any of them and I ended up following the solution that @liamharper2453 commented on:

public static class ApplicationBuilderExtensions
{
    public static IApplicationBuilder UseSwaggerForOcelot(this IApplicationBuilder app, IConfiguration configuration)
    {
        const string swaggerDocsPath = "/swagger/docs";
        bool hasPathBase = !string.IsNullOrEmpty(configuration["PATH_BASE"]);
        string pathBase = hasPathBase ? configuration["PATH_BASE"] : string.Empty;

        app.UseSwaggerForOcelotUI(
            options =>
            {
                options.PathToSwaggerGenerator = swaggerDocsPath;
                options.DownstreamSwaggerEndPointBasePath = pathBase + swaggerDocsPath;
                options.ReConfigureUpstreamSwaggerJson = (HttpContext _, string swaggerJson) =>
                {
                    if (!hasPathBase)
                    {
                        return swaggerJson;
                    }

                    return JObject.Parse(swaggerJson.Replace("\"/api/v", $"\"{pathBase}/api/v")).ToString(Formatting.Indented);
                };
            },
            options => options.OAuthClientId("apigwswagger"));

        return app;
    }
}

I understand that it's not the best solution, but it's the one I managed to make work, if anyone has a better solution I accept suggestions.