How to change default elasticsearch password in docker-compose?

Question

Elasticsearch's official docker image documentation provides this docker-compose.yml example:

version: '2'
services:
  elasticsearch1:
    image: docker.elastic.co/elasticsearch/elasticsearch:5.6.3
    container_name: elasticsearch1
    environment:
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    mem_limit: 1g
    volumes:
      - esdata1:/usr/share/elasticsearch/data
    ports:
      - 9200:9200
    networks:
      - esnet
  elasticsearch2:
    image: docker.elastic.co/elasticsearch/elasticsearch:5.6.3
    environment:
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
      - "discovery.zen.ping.unicast.hosts=elasticsearch1"
    ulimits:
      memlock:
        soft: -1
        hard: -1
    mem_limit: 1g
    volumes:
      - esdata2:/usr/share/elasticsearch/data
    networks:
      - esnet

volumes:
  esdata1:
    driver: local
  esdata2:
    driver: local

networks:
  esnet:

However, it doesn't explain how to customize the password. It does direct us to a X-Pack documentation page, but I refuse to believe I have to go through all that trouble just to change a password. Is there any simpler, canonical way of configuring a custom password for elasticsearch on a Docker Compose file?

Answer 1

Starting from 6.0 elasticsearch docker images has the ability to configure the password using the following environment variable - ELASTIC_PASSWORD.
For example:
docker run -e ELASTIC_PASSWORD=MagicWord docker.elastic.co/elasticsearch/elasticsearch-platinum:6.1.3
See: https://www.elastic.co/guide/en/elasticsearch/reference/6.1/docker.html