Fluentd collects events from various data sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop and so on. Fluentd helps you unify your logging infrastructure. Fluentd can be used to tail access/error logs and transport them reliably to remote systems. It can "grep" for events and send out alerts. It can function as middleware to enable asynchronous, scalable logging for user action events.