Creating brokers - Develop | Serverless | OpenShift Container Platform 4.9

Creating a broker by using the Knative CLI
Creating a broker by annotating a trigger
Creating a broker by labeling a namespace
Deleting a broker that was created by injection
Creating a broker by using the web console
Creating a Kafka broker when it is not configured as the default broker type
- Creating a Kafka broker by using YAML
- Creating a Kafka broker that uses an externally managed Kafka topic
Managing brokers
- Listing existing brokers by using the Knative CLI
- Describing an existing broker by using the Knative CLI
Next steps
Additional resources

Knative provides a default, channel-based broker implementation. This channel-based broker can be used for development and testing purposes, but does not provide adequate event delivery guarantees for production environments.

If a cluster administrator has configured your OpenShift Serverless deployment to use Kafka as the default broker type, creating a broker by using the default settings creates a Kafka-based broker.

If your OpenShift Serverless deployment is not configured to use Kafka broker as the default broker type, the channel-based broker is created when you use the default settings in the following procedures.

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/.

Creating a broker by using the Knative CLI

Brokers can be used in combination with triggers to deliver events from an event source to an event sink. Using the Knative (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.

Prerequisites

The OpenShift Serverless Operator and Knative Eventing are installed on your OpenShift Container Platform cluster.
You have installed the Knative (kn) CLI.
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.

Procedure

Create a broker:
```
$ kn broker create <broker_name>
```

Verification

Use the kn command to list all existing brokers:

$ kn broker list

Example output

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:

Creating a broker by annotating a trigger

Brokers can be used in combination with triggers to deliver events from an event source to an event sink. You can create a broker by adding the eventing.knative.dev/injection: enabled annotation to a Trigger object.

If you create a broker by using the eventing.knative.dev/injection: enabled annotation, you cannot delete this broker without cluster administrator permissions. If you delete the broker without having a cluster administrator remove this annotation first, the broker is created again after deletion.

Prerequisites

The OpenShift Serverless Operator and Knative Eventing are installed on your OpenShift Container Platform cluster.
Install the OpenShift CLI (oc).
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.

Procedure

Create a Trigger object as a YAML file that has the eventing.knative.dev/injection: enabled annotation:

apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  annotations:
    eventing.knative.dev/injection: enabled
  name: <trigger_name>
spec:
  broker: default
  subscriber: (1)
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: <service_name>

1	Specify details about the event sink, or subscriber, that the trigger sends events to.

Apply the Trigger YAML file:
```
$ oc apply -f <filename>
```

Verification

You can verify that the broker has been created successfully by using the oc CLI, or by observing it in the Topology view in the web console.

Enter the following oc command to get the broker:

$ oc -n <namespace> get broker default

Example output

NAME      READY     REASON    URL                                                                     AGE
default   True                http://broker-ingress.knative-eventing.svc.cluster.local/test/default   3m56s

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: