Latest release (2.5.1) breaks standard swagger ui servers definition

[code-mc]

Description

The 2.5.1 release introduced changes which modify the raw openapi spec servers definition which results in a swagger ui deployment that generates invalid requests.

e.g. When you specify

servers:
  - url: /api  

And a path in your openapi spec:

paths:
  /resource/update:
    .
    .
    .
  /resource/list:
    .
    .
    .

It will generate a swagger-ui with a server "/api/resource". I suppose this is because they both share the same prefix, but this then results in the swagger ui sending requests to "/api/resource/resource/update" and "/api/resource/resource/list" instead of the expected "/api/resource/update" and "/api/resource/list".

Expected behaviour

The defined servers openapi spec property is left untouched.

Actual behaviour

The defined servers property is modified to an invalid value which breaks sending requests using swagger ui.

Steps to reproduce

See description

Additional info:

Output of the commands:

• python --version
  Python 3.6.9

• pip show connexion | grep "^Version\:"
  Version: 2.5.1

[dtkav]

are you using flask or aiohttp?

[dtkav]

I was unable to reproduce the issue.
Here is my setup:

import connexion                                                                                                                
  
def create_app():  
    cxn = connexion.FlaskApp(__name__.split('.')[0], specification_dir='.')     
    cxn.add_api('spec.yaml', strict_validation=True, arguments={'title': 'Hello World Example'})  
    return cxn.app  
  
app = create_app()                                                                                    
app.run()  

openapi: "3.0.0"                                                                                                                
                   
info:                                                                           
  title: Hello World                                                                              
  version: "2"      
servers:
  - url: /v1.0                                                                                        
           
paths:
  /test/nested:
    get:
      operationId: hello.greet
      summary: A test endpoint.
      responses:
        "200":
          description: OK.

def greet() -> str:
    return "hello"

are you overriding base_path or something?

[dtkav]

New in 2.5.1, the request path is introspected to support using a path-altering reverse proxy (like aws api gateway). The PR for that change is #823
If you are using a path-altering reverse proxy, or have changed the flask internals that effect url_for(), that could be related.

[dtkav]

@code-mc can you provide any more information that could help me reproduce the issue? Are you using a path-altering reverse proxy?

[code-mc]

I'll try to supply a minimal flask script to reproduce, we encountered this in our production units so there might be some less used openapi features in our specs

[code-mc]

Ok so the bug seems to be related to something else than what I initially thought which explains why it couldn't be reproduced using the info I provided. The following is a minimal example to reproduce the bug:

Flask app.py:

import os

import connexion

def endpoint_1(req):
    pass
def endpoint_2(req):
    pass
def endpoint_3(req):
    pass

application = connexion.App(__name__)
app = application.app

openapi_spec = {
  "openapi": "3.0.0",
  "info": {
    "version": "0.0.1",
    "title": "Example API"
  },
  "servers": [
    {
      "url": "/api"
    }
  ],
  "paths": {
    "/some/path": {
      "get": {
        "operationId": "app.endpoint_1",
        "parameters": [],
        "responses": {
          "200": {
            "content": {
              "application/json": {
                "schema": {
                  "type": "object"
                }
              }
            },
            "description": "OK"
          }
        }
      }
    }
  }
}

application.add_api(openapi_spec, options={
    "swagger_url": "/ui",
    "openapi_spec_path": "/this-should-not-appear-in-the-servers/openapi.json",
})
app.openapi_spec = openapi_spec

The actual issue is that the openapi_spec_path is somehow influencing the generated "servers", which should be pulled from the servers field in the openapi spec.

Resulting swagger ui:

[dtkav]

Thanks for providing a minimal reproducible example. This is related to the feature to support path-altering reverse-proxies #823 , and it has turned out to be surprisingly tricky...