version: "3"
services:
  mongo:
    image: mongo
    container_name: mongo-container
    environment:
      - MONGO_INITDB_ROOT_USERNAME=root_username
      - MONGO_INITDB_ROOT_PASSWORD=very_secure_root_pass
    volumes:
      - /where/to/store/your/mongodb/data:/data/db
      - "/path/where/you/saved/your/bash/script/:/docker-entrypoint-initdb.d/"