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KafkaVersion

What is KafkaVersion

KafkaVersion is a Kubernetes Custom Resource Definitions (CRD). It provides a declarative configuration to specify the docker images to be used for Kafka database deployed with KubeDB in a Kubernetes native way.

When you install KubeDB, a KafkaVersion custom resource will be created automatically for every supported Kafka versions. You have to specify the name of KafkaVersion crd in spec.version field of Kafka crd. Then, KubeDB will use the docker images specified in the KafkaVersion crd to create your expected database.

Using a separate crd for specifying respective docker images, and pod security policy names allow us to modify the images, and policies independent of KubeDB operator.This will also allow the users to use a custom image for the database.

KafkaVersion Spec

As with all other Kubernetes objects, a KafkaVersion needs apiVersion, kind, and metadata fields. It also needs a .spec section.

apiVersion: catalog.kubedb.com/v1alpha1
kind: KafkaVersion
metadata:
  annotations:
    meta.helm.sh/release-name: kubedb-catalog
    meta.helm.sh/release-namespace: kubedb
  creationTimestamp: "2023-03-23T10:15:24Z"
  generation: 2
  labels:
    app.kubernetes.io/instance: kubedb-catalog
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: kubedb-catalog
    app.kubernetes.io/version: v2023.02.28
    helm.sh/chart: kubedb-catalog-v2023.02.28
  name: 3.4.0
  resourceVersion: "472767"
  uid: 36a167a3-5218-4e32-b96d-d6b5b0c86125
spec:
  db:
    image: kubedb/kafka-kraft:3.4.0
  podSecurityPolicies:
    databasePolicyName: kafka-db
  version: 3.4.0

metadata.name

metadata.name is a required field that specifies the name of the KafkaVersion crd. You have to specify this name in spec.version field of Kafka crd.

We follow this convention for naming KafkaVersion crd:

• Name format: {Original Kafka image version}-{modification tag}

We use official Apache Kafka release tar files to build docker images for supporting Kafka versions and re-tag the image with v1, v2 etc. modification tag when there’s any. An image with higher modification tag will have more features than the images with lower modification tag. Hence, it is recommended to use KafkaVersion crd with the highest modification tag to enjoy the latest features.

spec.version

spec.version is a required field that specifies the original version of Kafka database that has been used to build the docker image specified in spec.db.image field.

spec.deprecated

spec.deprecated is an optional field that specifies whether the docker images specified here is supported by the current KubeDB operator.

The default value of this field is false. If spec.deprecated is set to true, KubeDB operator will skip processing this CRD object and will add a event to the CRD object specifying that the DB version is deprecated.

spec.db.image

spec.db.image is a required field that specifies the docker image which will be used to create StatefulSet by KubeDB operator to create expected Kafka database.

spec.podSecurityPolicies.databasePolicyName

spec.podSecurityPolicies.databasePolicyName is a required field that specifies the name of the pod security policy required to get the database server pod(s) running.

helm upgrade kubedb-operator appscode/kubedb --namespace kube-system \
  --set additionalPodSecurityPolicies[0]=custom-db-policy \
  --set additionalPodSecurityPolicies[1]=custom-snapshotter-policy

Next Steps

• Learn about Kafka crd here.
• Deploy your first Kafka database with KubeDB by following the guide here.