How to hide sensitive data in docker-compose file

Question

services:
  mys-backend:
    restart: always
    build: .
    container_name: mys-backend
    ports:
      - '9095:8080'
    links:
      - 'mys-database:database'
    depends_on:
      - mys-database
    environment:
      - SPRING_DATASOURCE_URL=jdbc:postgresql://${POSTGRES_HOST}:${POSTGRES_PORT}/${DB_NAME}
      - SPRING_DATASOURCE_USERNAME=${POSTGRES_USER}
      - SPRING_DATASOURCE_PASSWORD=${POSTGRES_PASSWORD}
  mys-database:
    ports:
      - '5432:5432'
    image: postgres:12-alpine
    container_name: mys-database
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USERNAME}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    volumes:
      - ./postgres-data:/var/lib/postgresql/data

I put all the values in the application.properties hoping that these values would be pulled up when I am running the docker compose up command but to no avail

Answer 1

You can use an .env file and set variables like:

POSTGRES_HOST = http://localhost
POSTGRES_PORT = 9095
...

and pass it to your Docker image:

docker-compose run image_to_run --env-file .env

Check Docker docs