How to use .env variable in Dockerfile in command?

Question

I have variable in.env EMAIL=mail@mail.com My docker-compose.yml look:

services:
  web:
    container_name: ${NAME}}
    environment:
      EMAIL: ${EMAIL}
    build: "."
    ports:
      - 3011:3000
    stdin_open: true
    tty: true
    volumes:
      - "./app:/src/app"

I want use EMAIL var in dockerfile, in command:

RUN  ssh-keygen -q -t rsa -N "EMAIL"  -f ~/.ssh/id_rsa 

How look like this command? "${EMAIL}"?

Answer 1

For this you should use build args :

# docker-compose.yml
services:
  web:
    build:
      context: "."
      args:
        EMAIL: ${EMAIL}
   # ...

# Dockerfile

# ...

ARG EMAIL
RUN ssh-keygen -q -t rsa -N "${EMAIL}" -f ~/.ssh/id_rsa