For VM and Containers (Docker), we can use logmet service (logging and metrics) as described in the Bluemix documentation. I wonder if we can use this service for Cloud Foundry app or not using log drain ( https://docs.cloudfoundry.org/devguide/services/log-management.html ).
Ref: https://developer.ibm.com/bluemix/2015/12/11/sending-logs-to-bluemix-using-logstash-forwarder/
For Cloud Foundry applications the Monitoring & Analytics service in the catalog provides similar functionality.