Support running under subpath

[HESOYAM-abuser]

Hi @muety

I set ANCHR_PUBLIC_URL="http://127.0.0.1:8080/anchr" to define my base URL root, but I'm encountering two issues:

1. Response URL Issue: When making requests to http://127.0.0.1:8080/anchr, the response URL redirects to http://127.0.0.1:8080/, which causes routing errors.

2. API and Resource Path Issue: When shortening links or uploading images, the requests go to http://127.0.0.1:8080/api instead of the expected http://127.0.0.1:8080/anchr/api. The responses also seem incorrect.

Expected Behavior

• Responses should be directed to http://127.0.0.1:8080/anchr.
• Requests for resources like APIs and uploaded images should follow the base URL and go to http://127.0.0.1:8080/anchr/api.

Actual Behavior

• Responses are directed to http://127.0.0.1:8080/.
• Resource requests ignore the base URL path, going to http://127.0.0.1:8080/api instead of http://127.0.0.1:8080/anchr/api.

Steps to Reproduce

1. Set ANCHR_PUBLIC_URL="http://127.0.0.1:8080/anchr".
2. Attempt to shorten a link or upload an image.
3. Observe the response URL and the API/resource request paths.

Possible Solution

• Adjust the routing to ensure the response and API/resource requests respect the base URL path.

[HESOYAM-abuser]

There is another issue regarding the URLs for images and short links. For images, the URL is fetched from the request header; however, for short links, it retrieves the URL from ANCHR_PUBLIC_URL. This discrepancy can be observed in the image I provided. I believe it would be better to source both from a single location to avoid potential problems.

[muety]

Thanks for bringing this up!

Currently, ANCHR_PUBLIC_URL is expected to be the root of the application, i.e. that path part of the URL is expected to effectively be /. A common approach to run applications under a subpath is to use a reverse proxy instead, e.g. see this example. However, Anchr doesn't support their either, currently.

I'm reluctant to add logic for running under a subpath to the application itself, as you suggested. While it would be possible to extend the role of ANCHR_PUBLIC_URL to fully customize frontend- and API URL's, it's quite uncommon, I think. I don't think I remember having seen something like that somewhere else before.

However, it would be totally legitimate to add support for running under a subpath when behind a reverse proxy. This would require to:

1. Dynamically set <a base href="...">
2. Replace all absolute API endpoint paths (/api/xyz) by relative paths (api/xyz) in the frontend
3. Make "Logout" button redirect to actual base path instead of /
4. ...

I'll add this as a feature request, but - honestly - won't be getting to it too soon, unfortunately.