Create a Kafka cluster

This document shows how to create a Kafka cluster.

Before you start

• Install kbcli if you want to create a Kafka cluster by kbcli.

• Install KubeBlocks by kbcli or by Helm.

• Make sure Kafka Addon is enabled with kbcli addon list. If this Addon is not enabled, enable it first. Both kbccli and Helm options are available.

  kbcli addon list
  >
  NAME                           VERSION         PROVIDER    STATUS     AUTO-INSTALL
  ...
  kafka                          0.9.0           community   Enabled    true
  ...

• To keep things isolated, create a separate namespace called demo throughout this tutorial.

  kubectl create namespace demo

note

• KubeBlocks integrates Kafka v3.3.2, running it in KRaft mode.
• You are not recommended to use kraft cluster in combined mode in a production environment.
• The controller number suggested ranges from 3 to 5, out of complexity and availability.

Create a Kafka cluster

kbcli

1. Create a Kafka cluster.

   The cluster creation command is simply kbcli cluster create. Further, you can customize your cluster resources as demanded by using the --set flag.

   kbcli cluster create kafka mycluster -n demo

   kbcli provides more options for creating a Kafka cluster, such as setting cluster version, termination policy, CPU, and memory. You can view these options by adding --help or -h flag.

   kbcli cluster create kafka --help
   
   kbcli cluster create kafka -h

2. Verify whether this cluster is created successfully.

   kbcli cluster list -n demo
   >
   NAME        NAMESPACE   CLUSTER-DEFINITION   VERSION       TERMINATION-POLICY   STATUS    CREATED-TIME
   mycluster   demo        kafka                kafka-3.3.2   Delete               Running   Sep 27,2024 15:15 UTC+0800

kubectl

1. Create a Kafka cluster. If you only have one node for deploying a cluster with multiple replicas, set spec.affinity.topologyKeys as null. But for a production environment, it is not recommended to deploy all replicas on one node, which may decrease the cluster availability.

   • Create a Kafka cluster in combined mode.

     # create kafka in combined mode 
     kubectl apply -f - <<EOF
     apiVersion: apps.kubeblocks.io/v1alpha1
     kind: Cluster
     metadata:
       name: mycluster
       namespace: demo
       annotations:
         "kubeblocks.io/extra-env": '{"KB_KAFKA_ENABLE_SASL":"false","KB_KAFKA_BROKER_HEAP":"-XshowSettings:vm -XX:MaxRAMPercentage=100 -Ddepth=64","KB_KAFKA_CONTROLLER_HEAP":"-XshowSettings:vm -XX:MaxRAMPercentage=100 -Ddepth=64","KB_KAFKA_PUBLIC_ACCESS":"false", "KB_KAFKA_BROKER_NODEPORT": "false"}'
         kubeblocks.io/enabled-pod-ordinal-svc: broker
     spec:
       clusterDefinitionRef: kafka
       clusterVersionRef: kafka-3.3.2
       terminationPolicy: Delete
       affinity:
         podAntiAffinity: Preferred
         topologyKeys:
         - kubernetes.io/hostname
       tolerations:
         - key: kb-data
           operator: Equal
           value: "true"
           effect: NoSchedule
       services:
       - name: bootstrap
         serviceName: bootstrap
         componentSelector: broker
         spec:
           type: ClusterIP
           ports:
           - name: kafka-client
             targetPort: 9092
             port: 9092
       componentSpecs:
       - name: broker
         componentDef: kafka-combine
         tls: false
         replicas: 1
         serviceAccountName: kb-kafka-cluster
         resources:
           limits:
             cpu: '0.5'
             memory: 0.5Gi
           requests:
             cpu: '0.5'
             memory: 0.5Gi
         volumeClaimTemplates:
         - name: data
           spec:
             accessModes:
             - ReadWriteOnce
             resources:
               requests:
                 storage: 20Gi
         - name: metadata
           spec:
             accessModes:
             - ReadWriteOnce
             resources:
               requests:
                 storage: 20Gi
       - name: metrics-exp
         componentDefRef: kafka-exporter
         componentDef: kafka-exporter
         replicas: 1
         resources:
           limits:
             cpu: '0.5'
             memory: 0.5Gi
           requests:
             cpu: '0.5'
             memory: 0.5Gi
     EOF

   • Create a Kafka cluster in separated mode.

     # Create kafka cluster in separated mode
     kubectl apply -f - <<EOF
     apiVersion: apps.kubeblocks.io/v1alpha1
     kind: Cluster
     metadata:
       name: kafka-cluster
       namespace: demo
       annotations:
         "kubeblocks.io/extra-env": '{"KB_KAFKA_ENABLE_SASL":"false","KB_KAFKA_BROKER_HEAP":"-XshowSettings:vm -XX:MaxRAMPercentage=100 -Ddepth=64","KB_KAFKA_CONTROLLER_HEAP":"-XshowSettings:vm -XX:MaxRAMPercentage=100 -Ddepth=64","KB_KAFKA_PUBLIC_ACCESS":"false", "KB_KAFKA_BROKER_NODEPORT": "false"}'
         kubeblocks.io/enabled-pod-ordinal-svc: broker
     spec:
       clusterDefinitionRef: kafka
       clusterVersionRef: kafka-3.3.2
       terminationPolicy: Delete
       affinity:
         podAntiAffinity: Preferred
         topologyKeys:
         - kubernetes.io/hostname
         tolerations:
           - key: kb-data
             operator: Equal
             value: "true"
             effect: NoSchedule
         services:
           - name: bootstrap
             serviceName: bootstrap
             componentSelector: broker
         spec:
             type: ClusterIP
             ports:
             - name: kafka-client
               targetPort: 9092
               port: 9092
     componentSpecs:
     - name: broker
       componentDef: kafka-broker
       tls: false
       replicas: 1
       serviceAccountName: kb-kafka-cluster
       resources:
         limits:
           cpu: '0.5'
           memory: 0.5Gi
         requests:
           cpu: '0.5'
           memory: 0.5Gi
       volumeClaimTemplates:
       - name: data
         spec:
           accessModes:
           - ReadWriteOnce
           resources:
             requests:
               storage: 20Gi
       - name: metadata
         spec:
           storageClassName: null
           accessModes:
           - ReadWriteOnce
           resources:
             requests:
               storage: 5Gi
     - name: controller
       componentDefRef: controller
       componentDef: kafka-controller
       tls: false
       replicas: 1
       serviceAccountName: kb-kafka-cluster
       resources:
         limits:
           cpu: '0.5'
           memory: 0.5Gi
         requests:
           cpu: '0.5'
           memory: 0.5Gi
       volumeClaimTemplates:
       - name: metadata
         spec:
           storageClassName: null
           accessModes:
           - ReadWriteOnce
           resources:
             requests:
               storage: 20Gi
     - name: metrics-exp
       componentDefRef: kafka-exporter
       componentDef: kafka-exporter
       replicas: 1
       resources:
         limits:
           cpu: '0.5'
           memory: 0.5Gi
         requests:
           cpu: '0.5'
           memory: 0.5Gi
     EOF

   Field	Definition
   metadata.annotations."kubeblocks.io/extra-env"	It defines Kafka broker's jvm heap setting.
   metadata.annotations.kubeblocks.io/enabled-pod-ordinal-svc	It defines kafka cluster annotation keys for nodeport feature gate. You can also setkubeblocks.io/enabled-node-port-svc: broker and kubeblocks.io/disabled-cluster-ip-svc: broker.
   spec.clusterDefinitionRef	It specifies the name of the ClusterDefinition for creating a specific type of cluster.
   spec.clusterVersionRef	It is the name of the cluster version CRD that defines the cluster version.
   spec.terminationPolicy	It is the policy of cluster termination. The default value is Delete. Valid values are DoNotTerminate, Halt, Delete, WipeOut. - DoNotTerminate blocks deletion operation. - Halt deletes workload resources such as statefulset and deployment workloads but keep PVCs. - Delete is based on Halt and deletes PVCs. - WipeOut is based on Delete and wipe out all volume snapshots and snapshot data from a backup storage location.
   spec.affinity	It defines a set of node affinity scheduling rules for the cluster's Pods. This field helps control the placement of Pods on nodes within the cluster.
   spec.affinity.podAntiAffinity	It specifies the anti-affinity level of Pods within a component. It determines how pods should spread across nodes to improve availability and performance.
   spec.affinity.topologyKeys	It represents the key of node labels used to define the topology domain for Pod anti-affinity and Pod spread constraints.
   spec.tolerations	It is an array that specifies tolerations attached to the cluster's Pods, allowing them to be scheduled onto nodes with matching taints.
   spec.services	It defines the services to access a cluster.
   spec.componentSpecs	It is the list of components that define the cluster components. This field allows customized configuration of each component within a cluster.
   spec.componentSpecs.componentDefRef	It is the name of the component definition that is defined in the cluster definition and you can get the component definition names with kubectl get clusterdefinition kafka -o json \| jq '.spec.componentDefs[].name'.
   spec.componentSpecs.name	It specifies the name of the component.
   spec.componentSpecs.replicas	It specifies the number of replicas of the component.
   spec.componentSpecs.resources	It specifies the resource requirements of the component.

2. Verify whether this cluster is created successfully.

   kubectl get cluster mycluster -n demo
   >
   NAME        CLUSTER-DEFINITION   VERSION       TERMINATION-POLICY   STATUS    AGE
   mycluster   kafka                kafka-3.3.2   Delete               Running   2m2s