Django on Elastic Beanstalk not detecting RDS environment variables (falls back to SQLite)

I am deploying a Django app to AWS Elastic Beanstalk and connecting it to an RDS PostgreSQL database.

My Django settings are configured to use PostgreSQL only if RDS_DB_NAME exists in os.environ, otherwise it falls back to SQLite.

However, even though RDS environment variables are defined in Elastic Beanstalk, Django behaves as if they are not present and falls back to SQLite.

settings.py

if 'RDS_DB_NAME' in os.environ:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.postgresql',
            'NAME': os.environ['RDS_DB_NAME'],
            'USER': os.environ['RDS_USERNAME'],
            'PASSWORD': os.environ['RDS_PASSWORD'],
            'HOST': os.environ['RDS_HOSTNAME'],
            'PORT': os.environ['RDS_PORT'],
        }
    }
else: 
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': BASE_DIR / 'db.sqlite3',
        }
    }

Elastic Beanstalk Environment Variables (from console)

Under Configuration → Environment properties:

RDS_DB_NAME=ebdb
RDS_USERNAME=vividvaultdb
RDS_PASSWORD=********
RDS_HOSTNAME=awseb-xxxxx.ap-south-1.rds.amazonaws.com
RDS_PORT=5432

All variables are clearly visible in the EB console.

django.config

option_settings:
  aws:elasticbeanstalk:container:python:
    WSGIPath: vividvault.wsgi:application
  aws:elasticbeanstalk:environment:proxy:staticfiles:
    /static: static

db-migrate.config

container_commands:
  01_migrate:
    command: "source /var/app/venv/*/bin/activate && python3 manage.py migrate"
    leader_only: true

option_settings:
  aws:elasticbeanstalk:application:environment:
    DJANGO_SETTINGS_MODULE: vividvault.settings

.elasticbeanstalk/config.yml

branch-defaults:
  main:
    environment: vividvault-env

global:
  application_name: vividvault-project
  default_platform: Python 3.11 running on 64bit Amazon Linux 2023
  default_region: ap-south-1
  profile: eb-cli
  sc: git
  workspace_type: Application

The Problem

When I SSH into the instance and open Django shell:

eb ssh
cd /var/app/current
source /var/app/venv/*/bin/activate
python3 manage.py shell

Then check:

import os
print("RDS_DB_NAME in env:", 'RDS_DB_NAME' in os.environ)
print(os.environ.get("RDS_DB_NAME"))

Output:

False
None

So Django does not see RDS_DB_NAME in os.environ, even though it is defined in Elastic Beanstalk configuration.

Because of this, Django enters the else block and uses SQLite instead of PostgreSQL.

Question

Why would Elastic Beanstalk show RDS environment variables in the console, but they are not available inside the running Django process (os.environ)?

Is this: