I believe the best way to achieve what you want in an elegant way is using direnv.

Solution

The proposed solution uses the following files:

• Dotenv file .env
• Direnv file .envrc
• Docker compose file docker-compose.yml
• Create Mongo init script create_mongo_init.sh
• Startup script up.sh

Direnv

First of all make sure you have direnv installed.

Docker-compose file

Edit the docker-compose.yml file and make sure it is as follows:

version: '3.7'

services:
    mongo:
        image: mongo:latest
        restart: always
        environment:
            MONGO_INITDB_ROOT_USERNAME: ${DB_USERNAME}
            MONGO_INITDB_ROOT_PASSWORD: ${DB_PASSWORD}
            MONGO_INITDB_DATABASE: ${DB_NAME}
        ports:
            - '27017-27019:27017-27019'
        volumes:
            - mongodb_database:/data/db
            - ./mongo-init.js:/docker-entrypoint-initdb.d/mongo-init.js:ro

.env file creation

Create a .env file and enter:

DB_USERNAME=username
DB_PASSWORD=password
DB_NAME=db_name

.envrc file creation

Type in your terminal:

echo dotenv > .envrc

You should see the output as follows:

direnv: error .envrc is blocked. Run `direnv allow` to approve its content.

Loading environment variables

So type in your terminal:

direnv allow .

If your Direnv installtion is alright, it loads the variables and outputs the following:

direnv: loading .envrc                                                                               
direnv: export +DB_NAME +DB_PASSWORD +DB_USERNAME

Mongo init script

Create a file named create_mongo_init.sh with the following:

#!/bin/sh

echo "\
print('mongo init start --------------------'); \n\
\n\
db.createUser( \n\
    { \n\
        user: \"$DB_USERNAME\", \n\
        pwd: \"$DB_PASSWORD\", \n\
        roles: [ \n\
            { \n\
                role: \"readWrite\", \n\
                db: \"$DB_NAME\" \n\
            } \n\
        ] \n\
    } \n\
) \n\
\n\
print('mongo init end ----------------------'); \n\
" > mongo-init.js

Startup script

Create a file named up.sh with the following contents:

#!/bin/sh

./create_mongo_init.sh
docker-compose up -d
rm mongo-init.js # Delete initialization script to avoid credentials leakage.

And the run it by entering:

. ./up.sh

This will help someone out!

Docker-compose.yml

version: "3.3"
services:
  mongo:
    image: mongo
    restart: always
    ports:
      - 27017:27017
    environment:
      MONGO_INITDB_ROOT_USERNAME: myuser
      MONGO_INITDB_ROOT_PASSWORD: mypass
      MONGO_URI: ${MONGO_URI}
      MONGO_USER: ${MONGO_USER}
      MONGO_PWD: ${MONGO_PWD}
      MONGO_DB_NAME: ${MONGO_DB_NAME}
      MONGO_URI_TEST: ${MONGO_URI_TEST}
      MONGO_USER_TEST: ${MONGO_USER_TEST}
      MONGO_PWD_TEST: ${MONGO_PWD_TEST}
      MONGO_DB_NAME_TEST: ${MONGO_DB_NAME_TEST}
      MONGO_URI_DOCKER: ${MONGO_URI_DOCKER}
      MONGO_USER_DOCKER: ${MONGO_USER_DOCKER}
      MONGO_PWD_DOCKER: ${MONGO_PWD_DOCKER}
      MONGO_DB_NAME_DOCKER: ${MONGO_DB_NAME_DOCKER}
    volumes:
      - ./volume/mongo-data:/data/db
      - ./mongo-init:/docker-entrypoint-initdb.d/:ro
      

mongo-entrypoint.sh

echo '################ MONGO ENTRYPOINT START ################';

mongo -- "$MONGO_INITDB_DATABASE" <<EOF
db = db.getSiblingDB('$MONGO_DB_NAME_DOCKER');
db.createUser(
  {
    user: '$MONGO_USER_DOCKER',
    pwd: '$MONGO_PWD_DOCKER',
    roles: [{ role: 'readWrite', db: '$MONGO_DB_NAME_DOCKER' }],
  },
);
db.createCollection('users');

db = db.getSiblingDB('$MONGO_DB_NAME');
db.createUser(
  {
    user: '$MONGO_USER',
    pwd: '$MONGO_PWD',
    roles: [{ role: 'readWrite', db: '$MONGO_DB_NAME' }],
  },
);
db.createCollection('users');

db = db.getSiblingDB('$MONGO_DB_NAME_TEST');
db.createUser(
  {
    user: '$MONGO_USER_TEST',
    pwd: '$MONGO_PWD_TEST',
    roles: [{ role: 'readWrite', db: '$MONGO_DB_NAME_TEST' },{ role: 'dbAdmin', db: '$MONGO_DB_NAME_TEST' }],
  },
);
db.createCollection('users');
EOF

echo '################ MONGO ENTRYPOINT END ################';

.env

MONGO_URI="mongodb://localhost:27017/vinsys_db_dev"
MONGO_USER='fancyuser'
MONGO_PWD='fancypass'
MONGO_DB_NAME='vinsys_db_dev'

MONGO_URI_TEST="mongodb://localhost:27017/vinsys_db_test"
MONGO_USER_TEST='fancyuser'
MONGO_PWD_TEST='fancypass'
MONGO_DB_NAME_TEST='vinsys_db_test'

MONGO_URI_DOCKER="mongodb://mongo:27017/vinsys_db_prod"
MONGO_USER_DOCKER='fancyuser'
MONGO_PWD_DOCKER='fancypass'
MONGO_DB_NAME_DOCKER='vinsys_db_prod'

The following code worked in mongo:6.0.4 docker image.

mongo-init.js

db.auth(process.env["MONGO_INITDB_ROOT_USERNAME"], process.env["MONGO_INITDB_ROOT_PASSWORD"])

db = db.getSiblingDB(process.env["MONGO_INITDB_DATABASE"])

db.createUser({
  user: process.env["MONGODB_USERNAME"],
  pwd: process.env["MONGODB_PASSWORD"],
  roles: [
    {
      role: 'readWrite',
      db: process.env["MONGODB_DATABASE"],
    },
  ],
});

.env file

MONGO_INITDB_ROOT_USERNAME=root
MONGO_INITDB_ROOT_PASSWORD=1qaz2WSX
MONGO_INITDB_DATABASE=admin
MONGODB_USERNAME=user
MONGODB_PASSWORD=password
MONGODB_DATABASE=rr-platform

docker-compose.yml

version: '3.8'

services:
  mongodb:
    image: mongo:6.0.4
    restart: unless-stopped
    env_file: .env
    ports:
      - '27017:27017'
    volumes:
      - ./.data/mongo:/data/db
      - ./mongo-init.js:/docker-entrypoint-initdb.d/mongo-init.js:ro