Create a Kafka cluster

This document shows how to create a Kafka cluster.

Before you start

• Install KubeBlocks.

• View all the database types and versions available for creating a cluster.

  Make sure the kafka cluster definition is installed. If the cluster definition is not available, refer to this doc to enable it first.

  kubectl get clusterdefinition kafka
  >
  NAME    TOPOLOGIES   SERVICEREFS   STATUS      AGE
  kafka                              Available   27m

  View all available versions for creating a cluster.

  kubectl get clusterversions -l clusterdefinition.kubeblocks.io/name=kafka

• 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 production environment.
• The controller number suggested ranges from 3 to 5, out of complexity and availability.

Create a Kafka cluster

• 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

note

If you only have one node for deploying a cluster with multiple replicas, set spec.affinity.topologyKeys as null.

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.