Fission RMQ Connector

This is a Fission KEDA Connector. It is deployed by KEDA and is used to consume data from the configured message queue and forward it to the respective Function. In other words: connecting the Function with the Message Queue.

More connectors can be found here: https://github.com/fission/keda-connectors.

A custom connector was created, as the existing AMQP connector can only consume and publish to a queue and not an exchange. Since SensorBucket uses Exchanges to route messages to the correct worker, this was a requirement.

The custom connector allows the Function to respond with a header X-AMQP-Topic which indicates to which topic the result should be published.

Configuration

The RMQ Connector requires the following environment variables to be set.

Variable	Description	Required	Default
HOST	The AMQP Host	Yes
QUEUE_NAME	The queue to consume from	Yes
AMQP_PREFETCH	The amount of messages allowed to fetch ahead. It makes sense to have this equal to the amount of parallel invocations the corresponding Function can have	Yes	5
EXCHANGE	The AMQP Exchange to publish to	Yes
HTTP_ENDPOINT	The HTTP Endpoint to invoke for every message. KEDA and Fission sets this to the corresponding Function URL by default	Yes	The corresponding Fission Function URL
MAX_RETRIES	How many times the HTTP Endpoint will be retried in case of an error	Yes	3
METRICS_ADDR	The endpoint on which prometheus metrics will be exposed	No	:2112