So, we need to connect our docker based django app to our RDS instance, here are the steps to do so.

Step 1

Remove DATABASE_URL=postgres://postgres from .envs/.production/.django

Step 2

Update .envs/.production/.postgres and setup your database credentials.

POSTGRES_HOST=              # db host
POSTGRES_PORT=              # db port
POSTGRES_DB=                # db name
POSTGRES_USER=              # db user
POSTGRES_PASSWORD=          # db pass

Step 3

Comment or remove Postgres volumes and services from production.yml file.

You will have to remove the complete postgres service.

# Filename: /production.yml`

volumes:
    # production_postgres_data: {} ## Remove or comment this
    # production_postgres_data_backups: {} ## Remove or comment this
...
services:
  django: &django
    depends_on:
      # - postgres ## Remove or comment this

# postgres: ## Remove or comment this whole block
    ...

Your Django app should now connect to your RDS database in production.

Feel free to leave any feedback or queries.