Docker映像：创建内部可用的环境变量

Question

On my image I want to set some environment variables eg: MY_VAR where it will have a static value eg: MY_VAR=12 but I do NOT want to be able to set it via docker's -e param or via docker-compose.yml's environment section.

Furthermore I do not want to be as build argument when i do either docker build or docker-compose build

How can I do that?

Answer 1

You can do that from an entrypoint script.

In your Dockerfile:

ENTRYPOINT ["/entrypoint.sh"]

Example entrypoint.sh:

#!/bin/sh
export VAR=foobar
exec /usr/bin/python "$@"

To be more flexible and allow setting it with the -e option:

export VAR=${VAR:-"foobar"}
...

Answer 2

The best solution for your question is to include an env_file on your docker-compose build

version: '3.2'
services:
  db:
    restart: always
    image: postgres:alpine
    volumes:
      - backup-data:/var/lib/postgresql/data
    env_file:
      - ./env/.dev

Then in your env_file:

POSTGRES_USER=my_user
POSTGRES_PASSWORD=my_password
POSTGRES_DB=my_db