add the posibility of specifying a url prefix

[jjguti]

this commit implements a prefix for urls, which allows easily deploying
dpaste into a "subdirectory". It adds a url_prefix to be read by default
from the environment which makes it especially suitable for using for
docker containers. For example, running

docker run -e PREFIX_URL=dpaste/ -p 8000:8000 barttc/dpaste

will make dpaste available on

http://localhost:8000/dpaste/

instead of the default http://localhost:8000

This is specially useful if you want to proxy dpaste from another host
and let it live in a sub-url. Without this commit all urls would be
incorrectly generated in this case.

[DarrenOfficial]

Thank you for your work.

I tested this, it doesn't work

steps that I did

git clone -b "feature/add-url-prefix" https://github.com/jjguti/dpaste.git jjguti

docker build -t dpaste:jjguti .
docker run -e PREFIX_URL=dpaste/ -p 8000:8000 dpaste:jjguti

The URL still only accessible at the root domain

[jjguti]

Hi Darren,

I double checked and apparently I mixed up the name of the environment variable, it should be URL_PREFIX and not PREFIX_URL. to run you should use:

docker run -e URL_PREFIX=dpaste/ -p 8000:8000 dpaste:jjguti

[DarrenOfficial]

Hello jjguti,

I just tested it, it works.
If you can rebase this, I would gladly push it to main.

[jjguti]

Hi,

rebased now.