Migration from Zookeper to Apache Kafka Raft (KRaft) for Kafka online

Prerequisites

To bootstrap from a live cluster, complete the following steps:

Make sure that all the operator and datastore pods are running before you begin the migration.

kubectl get all -n instana-kafka

Migration Steps

1. You must enable node-pool to support both broker and controller.

   kubectl annotate kafka instana -n instana-kafka strimzi.io/node-pools="enabled" --overwrite
   

2. Disable KRaft.

   kubectl annotate kafka instana -n instana-kafka strimzi.io/kraft="disabled" --overwrite
   

3. Create a YAML file for the broker. For example, kafka-broker.yaml with the broker configuration.

   apiVersion: kafka.strimzi.io/v1beta2
   kind: KafkaNodePool
   metadata:
     name: kafka
     labels:
       strimzi.io/cluster: instana
   spec:
     replicas: 3
     roles:
        - broker
     storage:
       type: jbod
       volumes:
         - id: 0
           type: persistent-claim
           size: 50Gi
           deleteClaim: true
     template:
       pod:
         tmpDirSizeLimit: 500Mi
   

4. Deploy Broker.

   kubectl apply -f kafka-broker.yaml -n instana-kafka
   

   Broker pods appear.

5. Create a YAML file for the controller. For example, kafka-controller.yaml with the controller configuration.

   apiVersion: kafka.strimzi.io/v1beta2
   kind: KafkaNodePool
   metadata:
     name: controller
     labels:
       strimzi.io/cluster: instana
   spec:
     replicas: 3
     roles:
       - controller
     storage:
       type: persistent-claim
       size: 50Gi
       deleteClaim: true
     template:
       pod:
         tmpDirSizeLimit: 500Mi
   

6. Deploy Controller.

   kubectl apply -f kafka-controller.yaml -n instana-kafka
   

   You can use this command to verify the state of node pools.

   kubectl get kafka kafka -n instana-kafka -o jsonpath='{.status.kafkaNodePools}'
   

7. Enable migration.

   kubectl annotate kafka instana -n instana-kafka strimzi.io/kraft="migration" --overwrite
   

8. Verify the migration status.

   kubectl get kafka instana -n instana-kafka -o jsonpath='{.status.kafkaMetadataState}'
   

9. Optional: Replica and storage fields in the kafka.yaml are ignored now. You can remove these fields from the file.

   apiVersion: kafka.strimzi.io/v1beta2
   kind: Kafka
   metadata:
     ...
   spec:
     kafka:
       ...
    #    storage:
    #      type: jbod
    #      volumes:
    #        - id: 0
    #         type: persistent-claim
    #         size: 50Gi
    #         deleteClaim: true
    #    template:
    #      pod:
    #        tolerations:
    #           - key: node.instana.io/monitor
    #             operator: Equal
    #             effect: NoSchedule
    #             value: "true"
    #             affinity:
    #               nodeAffinity:
    #                 requiredDuringSchedulingIgnoredDuringExecution:
    #                    nodeSelectorTerms:
    #                      - matchExpressions:
    #                          - key: node-role.kubernetes.io/monitor
    #                            operator: In
    #                            values:
    #                            - "true"
    #  zookeeper:
    #    replicas: 3
    #      storage:
    #      type: persistent-claim
    #      size: 5Gi
    #      deleteClaim: true
    #      template:
    #        pod:
    #          tolerations:
    #            - key: node.instana.io/monitor
    #              operator: Equal
    #              effect: NoSchedule
    #              value: "true"
    #              affinity:
    #                nodeAffinity:
    #                  requiredDuringSchedulingIgnoredDuringExecution:
    #                     nodeSelectorTerms:
    #                        - matchExpressions:
    #                            - key: node-role.kubernetes.io/monitor
    #                              operator: In
    #                              values:
    #                              - "true"
   

entityOperator: ...

10. Set the KRaft status to enable when the state is 'KRaftPostMigration'.

```bash {: codeblock}
kubectl annotate kafka instana -n instana-kafka strimzi.io/kraft="enabled" --overwrite

Broker and controller pods are restarted. Kafka and Zookeeper pods are terminated.

11. Verify the migration status again.

kubectl get kafka instana -n instana-kafka -o jsonpath='{.status.kafkaMetadataState}'

The state must show KRaft now.

12. Verify the deployment.

kubectl get all -n instana-kafka

The output might be as the following example.

NAME                                           READY   STATUS    RESTARTS   AGE
pod/instana-entity-operator-8564975588-mrz2f   3/3     Running   0          15m
pod/instana-kafka-0                            1/1     Running   0          16m
pod/instana-kafka-1                            1/1     Running   0          16m
pod/instana-kafka-2                            1/1     Running   0          16m
pod/instana-controller-0                       1/1     Running   0          17m
pod/instana-controller-1                       1/1     Running   0          17m
pod/instana-controller-2                       1/1     Running   0          17m
pod/strimzi-cluster-operator-cf49c75d8-qm8jq   1/1     Running   0          34m

NAME                               TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
service/instana-kafka-bootstrap    ClusterIP   192.168.1.239   <none>        9091/TCP,9092/TCP            16m
service/instana-kafka-brokers      ClusterIP   None            <none>        9090/TCP,9091/TCP,9092/TCP   16m

NAME                                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/instana-entity-operator    1/1     1            1           15m
deployment.apps/strimzi-cluster-operator   1/1     1            1           34m

NAME                                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/instana-entity-operator-8564975588   1         1         1       15m
replicaset.apps/strimzi-cluster-operator-cf49c75d8   1         1         1       34m