How to pass environment variable to docker-compose up

Solution 1:

You have two options:

1. Create the .env file as already suggested in another answer.

2. Prepend KEY=VALUE pair(s) to your docker-compose command, e.g:

   KB_DB_TAG_VERSION=kb-1.3.20-v1.0.0 docker-compose up
   

   Exporting it earlier in a script should also work, e.g.:

   export KB_DB_TAG_VERSION=kb-1.3.20-v1.0.0
   docker-compose up
   

Solution 2:

You can create a .env file on the directory where you execute the docker-compose up command (and your docker-compose.yml file is located) with the following content:

KB_DB_TAG_VERSION=kb-1.3.20-v1.0.0

Your docker-compose.yml file should look like the following (added { and }):

version: '3'
services:
   db:
     user: "1000:50"
     volumes:
       - /data/mysql:/var/lib/mysql
     container_name: k-db
     environment:
       - MYSQL_ALLOW_EMPTY_PASSWORD=yes
     image: XX:${KB_DB_TAG_VERSION}
     image: k-db
     ports:
       - "3307:3306"

After making the above changes , check whether the changes are reflected or not using the command docker-compose config. The variable will be replaced by the variable value. Please refer to the page here to understand more about variable replacement.

Solution 3:

Just to supplement what has been outlined by others, in particular by @JakubKukul

For security purposes you probably wouldn't want to keep vulnerable information such as username/password in your docker-compose files if they're under version control. You can map environment variables that you have on your host to environment variables inside container as well. In this case it could be something like the following:

version: '3'
services:
   db:
    #build: k-db
    user: "1000:50"
    volumes:
      - /data/mysql:/var/lib/mysql
    container_name: k-db
    environment:
      - MYSQL_ALLOW_EMPTY_PASSWORD=yes
      - MYSQL_PASSWORD=${MYSQL_PASSWORD}
    image:  XX:$KB_DB_TAG_VERSION
    image: k-db
    ports:
      - "3307:3306"

where MYSQL_PASSWORD would be both:

1. An environment variable on your host (maybe just in the current shell session)
2. An environment variable inside the containers from the db service