logging-operator | golang based CRD operator to setup and manage | Continuous Deployment library

Performance and resource utilization. FluentBit is much more lightweight and therefore less expensive to run as a DaemonSet. Forwarding on to FluentD also makes sense, since FluentD has hundreds more plugins and is generally more flexible and configurable. The FluentBit docs themselves say:

Fluentd is a great option due to it flexibility and availability of plugins (more than 300 extensions!) but if the data collection will happen in an Embedded environment or an IoT device where the system capacity is restricted, Fluent Bit is the solution to use.

So what it looks like this operator is doing is using FluentBit to forward the logs in as lightweight a process as possible, then using FluentD to do the heavy processing/aggregating/shipping to destinations, the same way an app might use its own log forwarder to send to FluentD (for example over the HTTP input from somewhere outside of Kubernetes) and then have FluentD manage processing those logs and shipping them to destinations.