How to pass environment variable to docker-compose up

Question

I am trying to run a container. I already have the image uploaded to private Docker registry. I want to write a compose file to download and deploy the image. But I want to

Answer 1

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.

Answer 2

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
   

Answer 3

In your docker-compose.yml file add

env_file:
  - .env_file

to your db service where .env_file is your .env file (change its name accordingly).

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