$ docker-compose run cli composer install
Starting m2_elasticsearch_1 ... done
Starting m2_db_1 ... done
Starting m2_redis_1 ... done
Composer could not find a composer.json file in /var/www/html
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
Composer could not find a composer.json file in /var/www/html 唔明