I’m starting the containers using podman compose. The compose.yaml like this,

services:
  db:
    image: mysql:8.0
    restart: always
    env_file:
      - .env.local
    ports:
      - 5432:5432

and varialbes are defined in .env.local like this,

# use by Drizzle ORM
DATABASE_USERNAME=dummy
DATABASE_PASSWORD=secret
DATABASE_NAME=demo

# use to start MySQL container
MYSQL_DATABASE=demo
MYSQL_USER=dummy
MYSQL_PASSWORD=secret
MYSQL_ROOT_PASSWORD=supersecret

the above configuration are working fine.

Now that there are duplicated variables like DATABASE_USERNAME and MYSQL_DATABASE and I tried to simplify the .env.local like this,

DATABASE_USERNAME=dummy
DATABASE_PASSWORD=secret
DATABASE_NAME=demo

MYSQL_DATABASE=${DATABASE_USERNAME}
MYSQL_USER=${DATABASE_USERNAME}
MYSQL_PASSWORD=${MYSQL_PASSWORD}
MYSQL_ROOT_PASSWORD=supersecret

and it looks like the interpolation does not work. Do you know what am I missing here?

See also Interpolation in Compose file specification