The Controller component implements the KafkaChannel CRD (api, client, reconciler, etc.) based on the latest knative-eventing SharedMain reconciler framework and utilities.
The controller is based against the KafkaChannel CRD and reconciles all such
instances in the K8S Cluster. It actually consists of two reconcilers, one for
watching "Kafka" Secrets (those in knative-eventing labelled
eventing-kafka.knative.dev/kafka-secret: "true") which provisions the Kafka
Topic and creates the Channel / Producer Deployment & Service, and another which
is watching KafkaChannel resources and creates the Dispatcher / Consumer
Deployment & Service.
Note - Deleting a KafkaChannel CRD instance is destructive in that it will Remove the Kafka Topic resulting in the loss of all events therein. While the Dispatcher and Producer will perform semi-graceful shutdown there is no attempt to "drain" the topic or complete incoming CloudEvents.
The current implementation supports the following mechanisms for handling Topic
creation / deletion as specified by the KAFKA_ADMIN_TYPE environment
variable...
- "kafka" - The default value if not specified is to use the standard Sarama Kafka ClusterAdmin implementation.
- "eventhub" - If you wish to use the implementation with Azure EventHubs you will need to specify this as a custom client/api must be used for such.
- "custom" - If you need to implement your own custom AdminClient you will use this value (see the common/kafka/README.md).