add GeoDjango dependencies on alpine docker

I want to use GeoDjango on alpine docker and should add some dependencies on docker to use postgis database, refers to Django website I have to install by $ sudo apt-get install binutils libproj-dev gdal-bin I found that gdal and gdal-dev have already existed on alpine, so I used RUN apk add gdal gdal-dev but after running this docker-compose exec web python manage.py migrate --noinput Django says that :

'django.contrib.gis.db.backends.postgis' isn't an available database backend.
Try using 'django.db.backends.XXX', where XXX is one of:
    'mysql', 'oracle', 'postgresql', 'sqlite3'

How to add GeoDjango dependencies on alpine dockerfile?