Hello, I was trying to achieve the same using Docker compose with my nginx webserver and got it work by doing following:

Doccano

1. in frontend/nuxt.config.js, set base to your subpath

...
export default {
  router: {
    base: '/mysubpath/'
  },
...

and set baseUrl from /v1 to /mysubpath/v1:

...
   env: {
    baseUrl: '/mysubpath/v1'
   },
...

2. rebuild the image and run:

docker-compose -f docker/docker-compose.prod.yml up --build

3. Configure conf.d/default.conf of my nginx webserver, not the one that comes with doccano's docker-compose.prod.yml:

    location /mysubpath/ {
        proxy_pass          http://doccano-nginx:8080/;
        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;
    }

where doccano-nginx is the name of the nginx container in docker/docker-compose.prod.yml

Django's admin area:

1. change STATIC_URL from /static/ to /mysubpath/static/ in backend/config/settings/base.py:

...
STATIC_URL = "/mysubpath/static/"
...

2. add following settings to backend/config/settings/production.py:

USE_X_FORWARDED_HOST = True
FORCE_SCRIPT_NAME = '/mysubpath/'

Hello, I was trying to achieve the same using Docker compose with my nginx webserver and got it work by doing following:

I run under python env and I have to additionally add the prefix to all urlpatterns in backend/config/urls.py

# Add 'prefix' to all urlpatterns
if settings.URL_PREFIX:
    urlpatterns = [path(f'{settings.URL_PREFIX}/', include(urlpatterns))]

and in backend/config/settings/base.py add

URL_PREFIX = "mysubpath"

Otherwise, I cannot log in.
Not sure if I miss anything else.

reference https://stackoverflow.com/a/56639722/18672686

Having this issue solved would be immensely useful for me.
I am working in a university environment where the URL for requests looks like public.path.com/machine-name/user-name/.
Using Apache reverse proxy rules I can preserve the URL when binding doccano to localhost.

ProxyPass my-name/doccano http://127.0.0.1:8090/my-name/doccano
ProxyPassReverse my-name/doccano http://127.0.0.1:8090/my-name/doccano

I hoped to apply tutorial on how to mount flask to subpath using gunicorn also for doccano but I am confused how doccano uses wsgi and how can I influence the django URL settings in doccano?

Can wsgi and gunicorn be used to easily run doccano with subpath? If yes, how?