How do I pass an argument along with docker-compose up?

Question

I have a docker-compose.yml file and in the terminal I am typing docker-compose up [something] but I would also like to pass an argument to docker-compose.yml. Is this possible? I've read about interpolation variables and tried to specify a variable in the .yml file using ${testval} and then docker-compose up [something] var="test" but I receive the following error:

WARNING: The testval variable is not set. Defaulting to a blank string.
ERROR: No such service: testval=test

Answer 1

Based on dnephin answer, I created this sample repo that you can pass an variable to docker-compose up.

The usage is simple:

MAC / LINUX

• TEST= docker-compose up to create and start both app and db container. The api should then be running on your docker daemon on port 3030.
• TEST=DO docker-compose up to create and start both app and db container. The api should execute the npm run test inside the package.json file.

WINDOWS (Powershell)

• $env:TEST="";docker-compose up to create and start both app and db container. The api should then be running on your docker daemon on port 3030.
• $env:TEST="do";docker-compose up to create and start both app and db container. The api should execute the npm run test inside the package.json file.

Answer 2

You need to ensure 2 things:

1. The docker-compose.yml has the environment variable declared. For example,

services:     app:         image: python3.7         environment:             - "SECRET_KEY=${SECRET_KEY}" 

2. have the variable available in the environment when docker-compose up is called:

SECRET_KEY="not a secret" docker-compose up 

Note that this is not equivalent to pass them during build, as it is not advisable to store secrets in docker images.