Your application lives only if containers remain alive. If you want to make data storage persistent use volumes.
How? Nothing change here:
docker-compose up -d
But docker-compose.yml has slightly changed:
version: '3.5'
services:
db:
image: drupaldocker/mariadb:10.3
environment:
MYSQL_ALLOW_EMPTY_PASSWORD: 'True'
volumes:
- db_volume:/var/lib/mysql
cli:
image: drupaldocker/php:7.0-cli-2.x
links:
- db
volumes:
- file_volume:/var/www/html
volumes:
db_volume:
file_volume: