Set env variables from one string URI for https://hub.docker.com/_/postgres

docker-entrypoint.sh

#!/bin/bash
set -Eeo pipefail
# check to see if this file is being run or sourced from another script
_is_sourced() {
	# https://unix.stackexchange.com/a/215279
	[ "${#FUNCNAME[@]}" -ge 2 ] \
		&& [ "${FUNCNAME[0]}" = '_is_sourced' ] \
		&& [ "${FUNCNAME[1]}" = 'source' ]
}

read -r POSTGRES_USER POSTGRES_PASSWORD POSTGRES_DB<<<$(echo "$POSTGRES_URI"|sed -e's,^.*://\([^:]*\):\([^@]*\)@[^/]*/\([^?]*\).*,\1 \2 \3,g');
export $POSTGRES_USER;
export $POSTGRES_PASSWORD;
export $POSTGRES_DB;

source /usr/local/bin/docker-entrypoint.sh

if ! _is_sourced; then
	_main "$@"
fi