Help us understand the problem. What is going on with this article?

docker-compose の .env ファイルとは? コンテナの中で使える環境変数ではなく、あくまで docker-compose の記法で評価されるらしい。( #docker ))

.env

MESSAGE=yes

docker-compose.yml

version: '3'
services:
  message:
    image: alpine
    command: "echo ${MESSAGE}"
  display-env:
    image: alpine
    command: env

run

コマンドとして渡したメッセージは表示されるが、環境変数が増えているわけではない。

$ docker-compose run message
yes
$ docker-compose run display-env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=925b3197c65a
TERM=xterm
HOME=/root

.env ファイルよりも docker-compose コマンドに渡す環境変数のほうが強い

$ docker-compose run message
yes

$ MESSAGE=overwritten docker-compose run message
overwritten

ref

Environment variables in Compose | Docker Documentation

Original by Github issue

https://github.com/YumaInaura/YumaInaura/issues/2617

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