// Module included in the following assemblies:
//
//  * serverless/eventing/channels/serverless-channel-default.adoc

:_mod-docs-content-type: PROCEDURE
[id="serverless-channel-default_{context}"]
= Configuring the default channel implementation

.Prerequisites

* You have administrator permissions on {product-title}.
* You have installed the {ServerlessOperatorName} and Knative Eventing on your cluster.
* If you want to use Knative channels for Apache Kafka as the default channel implementation, you must also install the `KnativeKafka` CR on your cluster.

.Procedure

* Modify the `KnativeEventing` custom resource to add configuration details for the `default-ch-webhook` config map:
+
[source,yaml]
----
apiVersion: operator.knative.dev/v1beta1
kind: KnativeEventing
metadata:
  name: knative-eventing
  namespace: knative-eventing
spec:
  config: <1>
    default-ch-webhook: <2>
      default-ch-config: |
        clusterDefault: <3>
          apiVersion: messaging.knative.dev/v1
          kind: InMemoryChannel
          spec:
            delivery:
              backoffDelay: PT0.5S
              backoffPolicy: exponential
              retry: 5
        namespaceDefaults: <4>
          my-namespace:
            apiVersion: messaging.knative.dev/v1beta1
            kind: KafkaChannel
            spec:
              numPartitions: 1
              replicationFactor: 1
----
<1> In `spec.config`, you can specify the config maps that you want to add modified configurations for.
<2> The `default-ch-webhook` config map can be used to specify the default channel implementation for the cluster or for one or more namespaces.
<3> The cluster-wide default channel type configuration. In this example, the default channel implementation for the cluster is `InMemoryChannel`.
<4> The namespace-scoped default channel type configuration. In this example, the default channel implementation for the `my-namespace` namespace is `KafkaChannel`.
+
[IMPORTANT]
====
Configuring a namespace-specific default overrides any cluster-wide settings.
====
