server: Add ability to mount server at prefix

[oluwandabira]

This is a helpful feature in cases where the server is behind a reverse proxy mounted on a non root path.

[ExtReMLapin]

Have you tried using something else than a prefix passed thru args ? like a dot before ?

[ngxson]

To be fair, most reverse proxies already support rewriting URL path, so I think this feature can be a bit redundant. Example with nginx: https://superuser.com/questions/435916/nginx-rewrite-rule-to-remove-path-node

I approve this change anyway as it's not adding to much code.

[oluwandabira]

Have you tried using something else than a prefix passed thru args ? like a dot before ?

I'm not sure I understand

[oluwandabira]

To be fair, most reverse proxies already support rewriting URL path, so I think this feature can be a bit redundant. Example with nginx: https://superuser.com/questions/435916/nginx-rewrite-rule-to-remove-path-node

I approve this change anyway as it's not adding to much code.

I recognize that this might be a niche and redundant feature. I just happened to be in a environment where I have access to a reverse proxy but I can't change or see the server configuration, I'm just given a path where the app will be hosted.

[ExtReMLapin]

Have you tried using something else than a prefix passed thru args ? like a dot before ?

I'm not sure I understand

I didn't met the issue you met, but I never had to hardcode paths like that in the backend/frontend.

For example at the office we have a flask server on port 8080, but apache2 mounts it on port 80 and endpoint mywebsite.com/myapp/

On the frontend, all we need to do it use the api endpoints like "./api/yolo" which automatically makes it call mywebsite.com/myapp/api/yolo

on the frontend, setting the endpoint to /api/yolo insead of ./api/yolo makes it call ``mywebsite.com/api/yolo` instead

We never ever had to hardcode paths

[oluwandabira]

I see, that might have worked but then I would have needed to change the frontend and I don't know enough react to bother.

[ExtReMLapin]

Literally a dot in front of the endpoint URL.

Literally a DOT, it's not witchcraft, no need to known react.

Even if the frontend is already compiled, go in the js, ctrl+f the endpoint in the minified JS, add a . and give a try

I still believe this PR makes no sense