Variable images in Docker-compose

Question

I want to assign a value to the drupal 'image' tag in a Docker-compose file.

docker-compose.yml

version: '3'
services:
  drupal:
    image: jonasvbogaert/digipolis-migration:latest
    container_name: drupalenv
    ports:
      - 8080:80
    volumes:
      - ../drupal_site_eloket-brandweerzonecentrum/:/var/www/html/
    restart: always
    environment:
      DRUPAL_SITE_NAME: Drupal
      DRUPAL_USER: admin
      DRUPAL_PASS: admin
  mariadb:
    image: mariadb:latest
    container_name: mariadbenv
    restart: always
    ports:
      - 3036:3036
    depends_on:
      - drupal
    environment:
      MYSQL_ROOT_PASSWORD: ""
      MYSQL_ALLOW_EMPTY_PASSWORD: 'yes'
      MYSQL_USER: drupal
      MYSQL_PASSWORD: drupal
      MYSQL_DATABASE: drupal

With the help of a shell script I want to ask the user what Drupal version they want to use. Based on their answer (7 or 8) I want the image value to switch between 2 images.

Answer 1

You can use environment variables in docker-compose.yml . Change below

image: jonasvbogaert/digipolis-migration:latest

to

image: jonasvbogaert/digipolis-migration:${DRUPAL_VERSION}

In your bash script you would use

export DRUPAL_VERSION=8 #will come from the user
docker-compose up -d

Both the images with given tag should actually exist beforehand. If you need to build them manually then you can use build args in your Dockerfile.