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 pass the TAG name as a variable from the docker-compose run command.My compose file looks like below. How can I pass the value for KB_DB_TAG_VERSION as part of docker-compose up command?

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     image:  XX:$KB_DB_TAG_VERSION     image: k-db     ports:       - "3307:3306" 

Answer 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 

Answer 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.