Configure Channels for Apache Kafka

Note

This guide assumes Knative Eventing is installed in the knative-eventing namespace. If you have installed Knative Eventing in a different namespace, replace knative-eventing with the name of that namespace.

To use Kafka Channels, you must:

1. Install the KafkaChannel custom resource definition (CRD).
2. Create a ConfigMap that specifies default configurations for how KafkaChannel instances are created.

Create a kafka-channel ConfigMap

1. Create a YAML file for the kafka-channel ConfigMap using the following template:

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: kafka-channel
     namespace: knative-eventing
   data:
     channel-template-spec: |
       apiVersion: messaging.knative.dev/v1beta1
       kind: KafkaChannel
       spec:
         numPartitions: 3
         replicationFactor: 1
   

   Note

   This example specifies two extra parameters that are specific to Kafka Channels; numPartitions and replicationFactor.

2. Apply the YAML file by running the command:

   kubectl apply -f <filename>.yaml
   

   Where <filename> is the name of the file you created in the previous step.

3. Optional. To create a Broker that uses Kafka Channels, specify the kafka-channel ConfigMap in the Broker spec. You can do this by creating a YAML file using the following template:

   apiVersion: eventing.knative.dev/v1
   kind: Broker
   metadata:
     annotations:
       eventing.knative.dev/broker.class: MTChannelBasedBroker
     name: kafka-backed-broker
     namespace: default
   spec:
     config:
       apiVersion: v1
       kind: ConfigMap
       name: kafka-channel
       namespace: knative-eventing
   

4. Apply the YAML file by running the command:

   kubectl apply -f <filename>.yaml
   

   Where <filename> is the name of the file you created in the previous step.

Enable/configure autoscaling of KafkaChannel dispatchers

To enable autoscaling of the KafkaChannel dispatcher you can read the instructions here