Flasgger / Swagger - apidocs works with localhost but not Openshift (You need to enable JavaScript to run this app)

Question

I am running a Python Flask server. A co-worker added Flasgger/Swagger support and I can successfully display the API using

http://localhost:5000/apidocs

Similarly, I can get the json version of the API

http://localhost:5000/api_documentation.json
  Python code configures that filename

That same code is deployed in an Openshift project and uses Traefik to route external requests to the Python Flask server

https://my-openshift-url-here/apidocs
  does not display the API
  only displays "Powered by Flasgger 0.9.5
https://my-openshift-url-here/api_documentation.json
  works same as the localhost request

Traefik keys off of the "apidocs" and "api_documentation.json" and routes it directly to the Python Flask server

        rule: PathPrefix(`/apidocs`)
        entryPoints:
          - web
        middlewares:
          - gzip
          - mysecurity-no-token
        service: my-python-server

      apidocumentation:
        rule: PathPrefix(`/api_documentation.json`)
        entryPoints:
          - web
        middlewares:
          - gzip
          - mysecurity-no-token
        service: my-python-server

What I see in my Chrome browser debugger (F12 - Network) for the swagger-ui-bundle.js response is "You need to enable JavaScript to run this app."

Why does this work in Chrome for the localhost version but not when accessing the server deployed on Openshift? Both are being accessed from the same Chrome window - just different tabs.

This is the Headers content of the apidocs request for the localhost version

    Request Method: GET
    Status Code: 200 OK
    Remote Address: 127.0.0.1:5000
    Referrer Policy: strict-origin-when-cross-origin
    Content-Length: 3041
    Content-Type: text/html; charset=utf-8
    Date: Thu, 19 Aug 2021 12:08:41 GMT
    Server: Werkzeug/2.0.1 Python/3.7.4
    Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
    Accept-Encoding: gzip, deflate, br
    Accept-Language: en-US,en;q=0.9
    Cache-Control: no-cache
    Connection: keep-alive
    Host: localhost:5000
    Pragma: no-cache
    sec-ch-ua: "Chromium";v="92", " Not A;Brand";v="99", "Google Chrome";v="92"
    sec-ch-ua-mobile: ?0
    Sec-Fetch-Dest: document
    Sec-Fetch-Mode: navigate
    Sec-Fetch-Site: none
    Sec-Fetch-User: ?1
    Upgrade-Insecure-Requests: 1
    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36

This is the Headers content of the apidocs request for the Openshift version

    Request Method: GET
    Status Code: 200 OK
    Remote Address: 123.456.789.123:443 (obfuscated, of course)
    Referrer Policy: origin
    content-encoding: gzip
    content-length: 1264
    content-type: text/html; charset=utf-8
    date: Thu, 19 Aug 2021 12:08:59 GMT
    server: istio-envoy
    vary: Accept-Encoding
    x-envoy-upstream-service-time: 28
    Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
    Accept-Encoding: gzip, deflate, br
    Accept-Language: en-US,en;q=0.9
    Cache-Control: no-cache
    Connection: keep-alive
    Host: my-openshift-server-url-here
    Pragma: no-cache
    sec-ch-ua: "Chromium";v="92", " Not A;Brand";v="99", "Google Chrome";v="92"
    sec-ch-ua-mobile: ?0
    Sec-Fetch-Dest: document
    Sec-Fetch-Mode: navigate
    Sec-Fetch-Site: none
    Sec-Fetch-User: ?1
    Upgrade-Insecure-Requests: 1
    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36

Answer 1

Turns out it was a Traefik routing issues. After the initial response to the /apidocs request, it was also making requests to /flasgger_static/foo. I had to add a route for flassgger_static in my Traefik routing table.

flassger:
  rule: PathPrefix(`/flasgger_static`)
  entryPoints:
    - web
  middlewares:
    - gzip
    - mysecurity-no-token
  service: my-python-server