Feeders
Conceptually, a feeder is anything that generates a Cirrus Process Payload and queues it for processing. In practice this could be anything from a user hand-rolling JSON and pasting it into the AWS console, to an automated process that turns external events into process payloads and publishes them to the Cirrus process topic.
Within a Cirrus project instance, however, the term feeder refers
specifically to an AWS Lambda function that takes arbitrary input in, generates
one or more Cirrus Process Payloads, and publishes them to the Cirrus process
SNS topic.
As a component with a Lambda base, the Lambda-based components documentation contains relevant information for this and other Lambda components.