You must especificate the file JSON wich have the proper configuration for your app wich environment do you want to use (declared in your ecosystem file).
pm2 start ecosystem_cluster_mode.json --env production
pm2 save (Autostart your application when PM2 service is started/restarted)
pm2 ls (Shows PM2 runnings apps)
netstat -ntpl | grep pm2 (Filter running PM2 applications)