Use docker-compose env variable in Dockerbuild file

Question

Having the following docker-compose file:

db:
    build: .
    environment:
        - MYSQL_ROOT_PASSWORD=password
        - ENV=test
    env_file: .env
         


        

Answer 1

It works ok this way:

docker-compose.yml

version: '3.5'

services:
    container:
        build:
            context: .
            args:
                ENV: ${ENV} # from .env file
        env_file:
            - .env

Dockerfile

# from compose args
ARG ENV 
ADD ${ENV}/data.xml /data/

.env

ENV=myenv

Thus all the values are taken from .env file