Brokers can be used in combination with triggers to deliver events from an event source to an event sink. Events are sent from an event source to a broker as an HTTP
POST request. After events have entered the broker, they can be filtered by CloudEvent attributes using triggers, and sent as an HTTP
POST request to an event sink.
There are multiple broker implementations available for use with OpenShift Serverless, each of which have different event delivery guarantees and use different underlying technologies. You can choose the broker implementation when creating a broker by specifying a broker class, otherwise the default broker class is used. The default broker class can be configured by cluster administrators.
The channel-based broker implementation internally uses channels for event delivery. Channel-based brokers provide different event delivery guarantees based on the channel implementation a broker instance uses, for example:
A broker using the
InMemoryChannel implementation is useful for development and testing purposes, but does not provide adequate event delivery guarantees for production environments.
A broker using the
KafkaChannel implementation provides the event delivery guarantees required for a production environment.
Kafka broker is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/.
The Kafka broker is a broker implementation that uses Kafka internally to provide at-least once delivery guarantees. It supports multiple Kafka versions, and has a native integration with Kafka for storing and routing events.
OpenShift Serverless provides a
default Knative broker that you can create by using the
kn CLI. You can also create the
default broker by adding the
eventing.knative.dev/injection: enabled annotation to a trigger, or by adding the
eventing.knative.dev/injection=enabled label to a namespace.
Brokers can be used in combination with triggers to deliver events from an event source to an event sink. Using the
kn CLI to create brokers provides a more streamlined and intuitive user interface over modifying YAML files directly. You can use the
kn broker create command to create a broker by using the
The OpenShift Serverless Operator and Knative Eventing are installed on your OpenShift Container Platform cluster.
You have installed the Knative (
You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.
$ kn broker create default
kn command to list all existing brokers:
$ kn broker list
NAME URL AGE CONDITIONS READY REASON default http://broker-ingress.knative-eventing.svc.cluster.local/test/default 45s 5 OK / 5 True
Optional: If you are using the OpenShift Container Platform web console, you can navigate to the Topology view in the Developer perspective, and observe that the broker exists: