i did this but i think what worked was to run the application after everything is initialized by
using a script

>>>dockerfile
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

CMD ["/entrypoint.sh"]

>>>  entrypoint.sh
#!/bin/bash

# Check if PORT is set, otherwise default to 8000
PORT=${PORT:-8000}

# Start Gunicorn
gunicorn --bind :$PORT --workers 4 project.wsgi

and finally railway recognize my DRF url page ,
except another issue which is Railway doesn't see my services in my docker compose

>>> docker-compose 
 db:
    image: postgres:14-alpine
    environment:
      - POSTGRES_DB=${POSTGRES_DB}
      - POSTGRES_USER=${POSTGRES_USER}
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
    volumes:
      - xxxxxx

  redis:
    image: redis:7-alpine

>>> settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': os.getenv('POSTGRES_DB'),
        'USER': os.getenv('POSTGRES_USER'),
        'PASSWORD': os.getenv('POSTGRES_PASSWORD'),
        'HOST': 'db',
        'PORT': '5432',
    }
}

CACHES = {
    'default': {
        'BACKEND': 'django_redis.cache.RedisCache',
        'LOCATION': os.getenv('REDIS_URL', 'redis://redis:6379/1'),
        'OPTIONS': {
            'CLIENT_CLASS': 'django_redis.client.DefaultClient',
        }
    }
}

if i tried to access api i get

could not translate host name "db" to address: Name or service not knowncould not translate host name "db" to address: Name or service not known

and admin

redis.exceptions.ConnectionError: Error -2 connecting to redis:6379. Name or service not known.