bug: Redoc Error

[LectomT]

Provide environment information

docker env

Ok to proceed? (y) y


  System:
    OS: Linux 6.8 Alpine Linux
    CPU: (48) x64 Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz
    Memory: 39.50 GB / 62.49 GB
    Container: Yes
    Shell: Unknown - /bin/sh
  Binaries:
    Node: 22.16.0 - /usr/local/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.9.2 - /usr/local/bin/npm

---

the error message is

Something went wrong...
Unsupported specification
Stack trace
Error: Unsupported specification
    at t.detectSpec (https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:23011)
    at https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:1135
    at Generator.next (<anonymous>)
    at https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:618
    at new Promise (<anonymous>)
    at r (https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:363)
    at b (https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:927)
    at https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:5327
    at Generator.next (<anonymous>)
    at a (https://cdn.redoc.ly/redoc/latest/bundles/redoc.standalone.js:2:420)

ReDoc Version: 2.5.0
Commit: 00bc6ed```

<img width="701" height="416" alt="Image" src="https://github.com/user-attachments/assets/4db117fa-07a3-43d7-936a-7d072be446cf" />

### Describe the bug

Can't access redoc page

### Link to reproduction

https://feedback.hmac.kr/_api/docs/redoc

### To reproduce

https://feedback.hmac.kr/_api/docs/redoc

### Additional information

_No response_

[jihun]

@LectomT

The issue seems to be that the URL serving your docs-json does not match the value referenced by docs/redoc. In fact, your docs-json is being served correctly at the following URL:
https://feedback.hmac.kr/_back/docs-json

However, it appears that the serving URL is different which is referenced by the following code section:
https://github.com/line/abc-user-feedback/blob/main/apps/api/src/domains/api/api.controller.ts#L47

Your docs site is currently referring the following url:
https://feedback.hmac.kr/docs-json

Therefore, my proposed solution is to modify the /docs/redoc URL to accept a query string, and if the query string is present, prioritize it.

For example, it could be formatted like this:
https://feedback.hmac.kr/_back/docs/redoc?host=https://feedback.hmac.kr/_back

What do you think?

[LectomT]

@jihun

Thank you for your reply.

Now I understand why it happened.

I serve WEB and API by nginx proxy like below

#my_nginx.conf
...      
        location /_back/ {
            proxy_pass http://api:4000/;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }

        location / {
            proxy_pass http://web:3000;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
...

Your suggestion is very intuitive but little messy and can't solve another problem.

I can run swagger (https://feedback.hmac.kr/_back/docs) but cannot use swaggers executions because of hostname issue.

I found swagger's base path setting : https://swagger.io/docs/specification/v3_0/api-host-and-base-path/

---

So, could you override redoc's serving URL(spec-url) and swagger's spec-url(base path) by BASE_URL which is set API's environment?

like <redoc spec-url='${process.env.BASE_URL}/docs-json'></redoc>

at https://github.com/line/abc-user-feedback/blob/main/apps/api/src/domains/api/api.controller.ts#L47

and

  const documentConfig = new DocumentBuilder()
    .addServer('${process.env.BASE_URL}')
    .build();

at https://github.com/line/abc-user-feedback/blob/main/apps/api/src/scripts/build-swagger-docs.ts#L42

thank you very much.

my best.

[jihun]

@LectomT

Thank you for reply.
I couldn't understand your suggestion. BASE_URL in API server env is indicating frontend host address(defaults to http://localhost:3000), not API server host address.

So,
<redoc spec-url='${process.env.BASE_URL}/docs-json'></redoc> would not work because it will refer to http://localhost:3000/docs-json which is not a served page.

Could you check this please?

[LectomT]

@jihun

Opps I misunderstood environments..

This was my docker-compose.yml

#my_docker-compose.yml
services:
  api:
    image: line/abc-user-feedback-api:latest
    hostname: api
    environment:
      - BASE_URL=https://feedback.hmac.kr/_back

please, proceed #1111 haha...

I thought BASE_URL was API_BASE_URL. But, It wasn't. I'm sorry for making you confused

Could you consider to add another API environment for Serving URL like EXTERNAL_URL for proxy serving?

Until that, your suggestion is very useful for me.

Thank you!

[jihun]

@LectomT

Hi, sorry for the late response.

After an internal review, we decided to update the BASE_URL to point to the API server. We also plan to update the docs so that this environment variable is properly recognized.

This will be included in the next release.