Docker environment variables from file

[helasz-hu]

Hi All,
Openmetadata has a lot of environment variables in its docker compose file. Using Docker Swarm it would come really handy, if the sensible ones (passwords, etc.) may be read from file. Postgres Docker Image has a very nice builtin function (see below) which checks whether the name of the Environment variable ends with '_FILE', and if so then it reads the value from the file (for example: DB_PASSWORD_FILE: /run/secrets/db_password). I would appreciate a similar solution in Openmetadata entrypoint scripts.

The official entrypoint script of Postgres reads:

# usage: file_env VAR [DEFAULT]
#    ie: file_env 'XYZ_DB_PASSWORD' 'example'
# (will allow for "$XYZ_DB_PASSWORD_FILE" to fill in the value of
#  "$XYZ_DB_PASSWORD" from a file, especially for Docker's secrets feature)
file_env() {
<------>local var="$1"
<------>local fileVar="${var}_FILE"
<------>local def="${2:-}"
<------>if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
<------><------>printf >&2 'error: both %s and %s are set (but are exclusive)\n' "$var" "$fileVar"
<------><------>exit 1
<------>fi
<------>local val="$def"
<------>if [ "${!var:-}" ]; then
<------><------>val="${!var}"
<------>elif [ "${!fileVar:-}" ]; then
<------><------>val="$(< "${!fileVar}")"
<------>fi
<------>export "$var"="$val"
<------>unset "$fileVar"
}

(Actual workaround /ie. hacking the entrypoint script/ we use is not a nice solution)