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Horizontal Scale Kafka Combined Cluster
This guide will show you how to use KubeDB Ops-manager operator to scale the Kafka combined cluster.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.Install
KubeDBProvisioner and Ops-manager operator in your cluster following the steps here.You should be familiar with the following
KubeDBconcepts:
To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/examples/kafka directory of kubedb/docs repository.
Apply Horizontal Scaling on Combined Cluster
Here, we are going to deploy a Kafka combined cluster using a supported version by KubeDB operator. Then we are going to apply horizontal scaling on it.
Prepare Kafka Combined cluster
Now, we are going to deploy a Kafka combined cluster with version 3.6.1.
Deploy Kafka combined cluster
In this section, we are going to deploy a Kafka combined cluster. Then, in the next section we will scale the cluster using KafkaOpsRequest CRD. Below is the YAML of the Kafka CR that we are going to create,
apiVersion: kubedb.com/v1
kind: Kafka
metadata:
name: kafka-dev
namespace: demo
spec:
replicas: 2
version: 3.6.1
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: standard
storageType: Durable
deletionPolicy: WipeOut
Let’s create the Kafka CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/kafka/scaling/kafka-combined.yaml
kafka.kubedb.com/kafka-dev created
Now, wait until kafka-dev has status Ready. i.e,
$ kubectl get kf -n demo -w
NAME TYPE VERSION STATUS AGE
kafka-dev kubedb.com/v1 3.6.1 Provisioning 0s
kafka-dev kubedb.com/v1 3.6.1 Provisioning 24s
.
.
kafka-dev kubedb.com/v1 3.6.1 Ready 92s
Let’s check the number of replicas has from kafka object, number of pods the petset have,
$ kubectl get kafka -n demo kafka-dev -o json | jq '.spec.replicas'
2
$ kubectl get petset -n demo kafka-dev -o json | jq '.spec.replicas'
2
We can see from both command that the cluster has 2 replicas.
Also, we can verify the replicas of the combined from an internal kafka command by exec into a replica.
Now let’s exec to a instance and run a kafka internal command to check the number of replicas,
$ kubectl exec -it -n demo kafka-dev-0 -- kafka-broker-api-versions.sh --bootstrap-server localhost:9092 --command-config config/clientauth.properties
kafka-dev-0.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 0 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
kafka-dev-1.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 1 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
We can see from the above output that the kafka has 2 nodes.
We are now ready to apply the KafkaOpsRequest CR to scale this cluster.
Scale Up Replicas
Here, we are going to scale up the replicas of the combined cluster to meet the desired number of replicas after scaling.
Create KafkaOpsRequest
In order to scale up the replicas of the combined cluster, we have to create a KafkaOpsRequest CR with our desired replicas. Below is the YAML of the KafkaOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: KafkaOpsRequest
metadata:
name: kfops-hscale-up-combined
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: kafka-dev
horizontalScaling:
node: 3
Here,
spec.databaseRef.namespecifies that we are performing horizontal scaling operation onkafka-devcluster.spec.typespecifies that we are performingHorizontalScalingon kafka.spec.horizontalScaling.nodespecifies the desired replicas after scaling.
Let’s create the KafkaOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/kafka/scaling/horizontal-scaling/kafka-hscale-up-combined.yaml
kafkaopsrequest.ops.kubedb.com/kfops-hscale-up-combined created
Verify Combined cluster replicas scaled up successfully
If everything goes well, KubeDB Ops-manager operator will update the replicas of Kafka object and related PetSets and Pods.
Let’s wait for KafkaOpsRequest to be Successful. Run the following command to watch KafkaOpsRequest CR,
$ watch kubectl get kafkaopsrequest -n demo
NAME TYPE STATUS AGE
kfops-hscale-up-combined HorizontalScaling Successful 106s
We can see from the above output that the KafkaOpsRequest has succeeded. If we describe the KafkaOpsRequest we will get an overview of the steps that were followed to scale the cluster.
$ kubectl describe kafkaopsrequests -n demo kfops-hscale-up-combined
Name: kfops-hscale-up-combined
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: KafkaOpsRequest
Metadata:
Creation Timestamp: 2024-08-02T10:19:56Z
Generation: 1
Resource Version: 353093
UID: f91de2da-82c4-4175-aab4-de0f3e1ce498
Spec:
Apply: IfReady
Database Ref:
Name: kafka-dev
Horizontal Scaling:
Node: 3
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2024-08-02T10:19:57Z
Message: Kafka ops-request has started to horizontally scaling the nodes
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2024-08-02T10:20:05Z
Message: get pod; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: GetPod--kafka-dev-0
Last Transition Time: 2024-08-02T10:20:05Z
Message: evict pod; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: EvictPod--kafka-dev-0
Last Transition Time: 2024-08-02T10:20:15Z
Message: check pod running; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: CheckPodRunning--kafka-dev-0
Last Transition Time: 2024-08-02T10:20:20Z
Message: get pod; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: GetPod--kafka-dev-1
Last Transition Time: 2024-08-02T10:20:20Z
Message: evict pod; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: EvictPod--kafka-dev-1
Last Transition Time: 2024-08-02T10:21:00Z
Message: check pod running; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: CheckPodRunning--kafka-dev-1
Last Transition Time: 2024-08-02T10:21:05Z
Message: Successfully restarted all nodes
Observed Generation: 1
Reason: RestartNodes
Status: True
Type: RestartNodes
Last Transition Time: 2024-08-02T10:22:15Z
Message: Successfully Scaled Up Server Node
Observed Generation: 1
Reason: ScaleUpCombined
Status: True
Type: ScaleUpCombined
Last Transition Time: 2024-08-02T10:21:10Z
Message: patch pet setkafka-dev; ConditionStatus:True
Observed Generation: 1
Status: True
Type: PatchPetSetkafka-dev
Last Transition Time: 2024-08-02T10:22:10Z
Message: node in cluster; ConditionStatus:True
Observed Generation: 1
Status: True
Type: NodeInCluster
Last Transition Time: 2024-08-02T10:22:15Z
Message: Successfully completed horizontally scale kafka cluster
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 4m34s KubeDB Ops-manager Operator Start processing for KafkaOpsRequest: demo/kfops-hscale-up-combined
Normal Starting 4m34s KubeDB Ops-manager Operator Pausing Kafka databse: demo/kafka-dev
Normal Successful 4m34s KubeDB Ops-manager Operator Successfully paused Kafka database: demo/kafka-dev for KafkaOpsRequest: kfops-hscale-up-combined
Warning get pod; ConditionStatus:True; PodName:kafka-dev-0 4m26s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:kafka-dev-0
Warning evict pod; ConditionStatus:True; PodName:kafka-dev-0 4m26s KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:kafka-dev-0
Warning check pod running; ConditionStatus:False; PodName:kafka-dev-0 4m21s KubeDB Ops-manager Operator check pod running; ConditionStatus:False; PodName:kafka-dev-0
Warning check pod running; ConditionStatus:True; PodName:kafka-dev-0 4m16s KubeDB Ops-manager Operator check pod running; ConditionStatus:True; PodName:kafka-dev-0
Warning get pod; ConditionStatus:True; PodName:kafka-dev-1 4m11s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:kafka-dev-1
Warning evict pod; ConditionStatus:True; PodName:kafka-dev-1 4m11s KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:kafka-dev-1
Warning check pod running; ConditionStatus:False; PodName:kafka-dev-1 4m6s KubeDB Ops-manager Operator check pod running; ConditionStatus:False; PodName:kafka-dev-1
Warning check pod running; ConditionStatus:True; PodName:kafka-dev-1 3m31s KubeDB Ops-manager Operator check pod running; ConditionStatus:True; PodName:kafka-dev-1
Normal RestartNodes 3m26s KubeDB Ops-manager Operator Successfully restarted all nodes
Warning patch pet setkafka-dev; ConditionStatus:True 3m21s KubeDB Ops-manager Operator patch pet setkafka-dev; ConditionStatus:True
Warning node in cluster; ConditionStatus:False 2m46s KubeDB Ops-manager Operator node in cluster; ConditionStatus:False
Warning node in cluster; ConditionStatus:True 2m21s KubeDB Ops-manager Operator node in cluster; ConditionStatus:True
Normal ScaleUpCombined 2m16s KubeDB Ops-manager Operator Successfully Scaled Up Server Node
Normal Starting 2m16s KubeDB Ops-manager Operator Resuming Kafka database: demo/kafka-dev
Normal Successful 2m16s KubeDB Ops-manager Operator Successfully resumed Kafka database: demo/kafka-dev for KafkaOpsRequest: kfops-hscale-up-combined
Now, we are going to verify the number of replicas this cluster has from the Kafka object, number of pods the petset have,
$ kubectl get kafka -n demo kafka-dev -o json | jq '.spec.replicas'
3
$ kubectl get petset -n demo kafka-dev -o json | jq '.spec.replicas'
3
Now let’s connect to a kafka instance and run a kafka internal command to check the number of replicas,
$ kubectl exec -it -n demo kafka-dev-0 -- kafka-broker-api-versions.sh --bootstrap-server localhost:9092 --command-config config/clientauth.properties
kafka-dev-0.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 0 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
kafka-dev-1.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 1 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
kafka-dev-2.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 2 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
From all the above outputs we can see that the brokers of the combined kafka is 3. That means we have successfully scaled up the replicas of the Kafka combined cluster.
Scale Down Replicas
Here, we are going to scale down the replicas of the kafka combined cluster to meet the desired number of replicas after scaling.
Create KafkaOpsRequest
In order to scale down the replicas of the kafka combined cluster, we have to create a KafkaOpsRequest CR with our desired replicas. Below is the YAML of the KafkaOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: KafkaOpsRequest
metadata:
name: kfops-hscale-down-combined
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: kafka-dev
horizontalScaling:
node: 2
Here,
spec.databaseRef.namespecifies that we are performing horizontal scaling down operation onkafka-devcluster.spec.typespecifies that we are performingHorizontalScalingon kafka.spec.horizontalScaling.nodespecifies the desired replicas after scaling.
Let’s create the KafkaOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/kafka/scaling/horizontal-scaling/kafka-hscale-down-combined.yaml
kafkaopsrequest.ops.kubedb.com/kfops-hscale-down-combined created
Verify Combined cluster replicas scaled down successfully
If everything goes well, KubeDB Ops-manager operator will update the replicas of Kafka object and related PetSets and Pods.
Let’s wait for KafkaOpsRequest to be Successful. Run the following command to watch KafkaOpsRequest CR,
$ watch kubectl get kafkaopsrequest -n demo
NAME TYPE STATUS AGE
kfops-hscale-down-combined HorizontalScaling Successful 2m32s
We can see from the above output that the KafkaOpsRequest has succeeded. If we describe the KafkaOpsRequest we will get an overview of the steps that were followed to scale the cluster.
$ kubectl describe kafkaopsrequests -n demo kfops-hscale-down-combined
Name: kfops-hscale-down-combined
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: KafkaOpsRequest
Metadata:
Creation Timestamp: 2024-08-02T10:46:39Z
Generation: 1
Resource Version: 354924
UID: f1a0b85d-1a86-463c-a3e4-72947badd108
Spec:
Apply: IfReady
Database Ref:
Name: kafka-dev
Horizontal Scaling:
Node: 2
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2024-08-02T10:46:39Z
Message: Kafka ops-request has started to horizontally scaling the nodes
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2024-08-02T10:47:07Z
Message: Successfully Scaled Down Server Node
Observed Generation: 1
Reason: ScaleDownCombined
Status: True
Type: ScaleDownCombined
Last Transition Time: 2024-08-02T10:46:57Z
Message: reassign partitions; ConditionStatus:True
Observed Generation: 1
Status: True
Type: ReassignPartitions
Last Transition Time: 2024-08-02T10:46:57Z
Message: is pet set patched; ConditionStatus:True
Observed Generation: 1
Status: True
Type: IsPetSetPatched
Last Transition Time: 2024-08-02T10:46:57Z
Message: get pod; ConditionStatus:True
Observed Generation: 1
Status: True
Type: GetPod
Last Transition Time: 2024-08-02T10:46:58Z
Message: delete pvc; ConditionStatus:True
Observed Generation: 1
Status: True
Type: DeletePvc
Last Transition Time: 2024-08-02T10:47:02Z
Message: get pvc; ConditionStatus:True
Observed Generation: 1
Status: True
Type: GetPvc
Last Transition Time: 2024-08-02T10:47:13Z
Message: successfully reconciled the Kafka with modified node
Observed Generation: 1
Reason: UpdatePetSets
Status: True
Type: UpdatePetSets
Last Transition Time: 2024-08-02T10:47:18Z
Message: get pod; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: GetPod--kafka-dev-0
Last Transition Time: 2024-08-02T10:47:18Z
Message: evict pod; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: EvictPod--kafka-dev-0
Last Transition Time: 2024-08-02T10:47:28Z
Message: check pod running; ConditionStatus:True; PodName:kafka-dev-0
Observed Generation: 1
Status: True
Type: CheckPodRunning--kafka-dev-0
Last Transition Time: 2024-08-02T10:47:33Z
Message: get pod; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: GetPod--kafka-dev-1
Last Transition Time: 2024-08-02T10:47:33Z
Message: evict pod; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: EvictPod--kafka-dev-1
Last Transition Time: 2024-08-02T10:48:53Z
Message: check pod running; ConditionStatus:True; PodName:kafka-dev-1
Observed Generation: 1
Status: True
Type: CheckPodRunning--kafka-dev-1
Last Transition Time: 2024-08-02T10:48:58Z
Message: Successfully restarted all nodes
Observed Generation: 1
Reason: RestartNodes
Status: True
Type: RestartNodes
Last Transition Time: 2024-08-02T10:48:58Z
Message: Successfully completed horizontally scale kafka cluster
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 2m39s KubeDB Ops-manager Operator Start processing for KafkaOpsRequest: demo/kfops-hscale-down-combined
Normal Starting 2m39s KubeDB Ops-manager Operator Pausing Kafka databse: demo/kafka-dev
Normal Successful 2m39s KubeDB Ops-manager Operator Successfully paused Kafka database: demo/kafka-dev for KafkaOpsRequest: kfops-hscale-down-combined
Warning reassign partitions; ConditionStatus:True 2m21s KubeDB Ops-manager Operator reassign partitions; ConditionStatus:True
Warning is pet set patched; ConditionStatus:True 2m21s KubeDB Ops-manager Operator is pet set patched; ConditionStatus:True
Warning get pod; ConditionStatus:True 2m21s KubeDB Ops-manager Operator get pod; ConditionStatus:True
Warning delete pvc; ConditionStatus:True 2m20s KubeDB Ops-manager Operator delete pvc; ConditionStatus:True
Warning get pvc; ConditionStatus:False 2m20s KubeDB Ops-manager Operator get pvc; ConditionStatus:False
Warning get pod; ConditionStatus:True 2m16s KubeDB Ops-manager Operator get pod; ConditionStatus:True
Warning delete pvc; ConditionStatus:True 2m16s KubeDB Ops-manager Operator delete pvc; ConditionStatus:True
Warning get pvc; ConditionStatus:True 2m16s KubeDB Ops-manager Operator get pvc; ConditionStatus:True
Normal ScaleDownCombined 2m11s KubeDB Ops-manager Operator Successfully Scaled Down Server Node
Normal UpdatePetSets 2m5s KubeDB Ops-manager Operator successfully reconciled the Kafka with modified node
Warning get pod; ConditionStatus:True; PodName:kafka-dev-0 2m KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:kafka-dev-0
Warning evict pod; ConditionStatus:True; PodName:kafka-dev-0 2m KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:kafka-dev-0
Warning check pod running; ConditionStatus:False; PodName:kafka-dev-0 115s KubeDB Ops-manager Operator check pod running; ConditionStatus:False; PodName:kafka-dev-0
Warning check pod running; ConditionStatus:True; PodName:kafka-dev-0 110s KubeDB Ops-manager Operator check pod running; ConditionStatus:True; PodName:kafka-dev-0
Warning get pod; ConditionStatus:True; PodName:kafka-dev-1 105s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:kafka-dev-1
Warning evict pod; ConditionStatus:True; PodName:kafka-dev-1 105s KubeDB Ops-manager Operator evict pod; ConditionStatus:True; PodName:kafka-dev-1
Warning check pod running; ConditionStatus:False; PodName:kafka-dev-1 100s KubeDB Ops-manager Operator check pod running; ConditionStatus:False; PodName:kafka-dev-1
Warning check pod running; ConditionStatus:True; PodName:kafka-dev-1 25s KubeDB Ops-manager Operator check pod running; ConditionStatus:True; PodName:kafka-dev-1
Normal RestartNodes 20s KubeDB Ops-manager Operator Successfully restarted all nodes
Normal Starting 20s KubeDB Ops-manager Operator Resuming Kafka database: demo/kafka-dev
Normal Successful 20s KubeDB Ops-manager Operator Successfully resumed Kafka database: demo/kafka-dev for KafkaOpsRequest: kfops-hscale-down-combined
Now, we are going to verify the number of replicas this cluster has from the Kafka object, number of pods the petset have,
$ kubectl get kafka -n demo kafka-dev -o json | jq '.spec.replicas'
2
$ kubectl get petset -n demo kafka-dev -o json | jq '.spec.replicas'
2
Now let’s connect to a kafka instance and run a kafka internal command to check the number of replicas,
$ kubectl exec -it -n demo kafka-dev-0 -- kafka-broker-api-versions.sh --bootstrap-server localhost:9092 --command-config config/clientauth.properties
kafka-dev-0.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 0 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
kafka-dev-1.kafka-dev-pods.demo.svc.cluster.local:9092 (id: 1 rack: null) -> (
Produce(0): 0 to 9 [usable: 9],
Fetch(1): 0 to 15 [usable: 15],
ListOffsets(2): 0 to 8 [usable: 8],
Metadata(3): 0 to 12 [usable: 12],
LeaderAndIsr(4): UNSUPPORTED,
StopReplica(5): UNSUPPORTED,
UpdateMetadata(6): UNSUPPORTED,
ControlledShutdown(7): UNSUPPORTED,
OffsetCommit(8): 0 to 8 [usable: 8],
OffsetFetch(9): 0 to 8 [usable: 8],
FindCoordinator(10): 0 to 4 [usable: 4],
JoinGroup(11): 0 to 9 [usable: 9],
Heartbeat(12): 0 to 4 [usable: 4],
LeaveGroup(13): 0 to 5 [usable: 5],
SyncGroup(14): 0 to 5 [usable: 5],
DescribeGroups(15): 0 to 5 [usable: 5],
ListGroups(16): 0 to 4 [usable: 4],
SaslHandshake(17): 0 to 1 [usable: 1],
ApiVersions(18): 0 to 3 [usable: 3],
CreateTopics(19): 0 to 7 [usable: 7],
DeleteTopics(20): 0 to 6 [usable: 6],
DeleteRecords(21): 0 to 2 [usable: 2],
InitProducerId(22): 0 to 4 [usable: 4],
OffsetForLeaderEpoch(23): 0 to 4 [usable: 4],
AddPartitionsToTxn(24): 0 to 4 [usable: 4],
AddOffsetsToTxn(25): 0 to 3 [usable: 3],
EndTxn(26): 0 to 3 [usable: 3],
WriteTxnMarkers(27): 0 to 1 [usable: 1],
TxnOffsetCommit(28): 0 to 3 [usable: 3],
DescribeAcls(29): 0 to 3 [usable: 3],
CreateAcls(30): 0 to 3 [usable: 3],
DeleteAcls(31): 0 to 3 [usable: 3],
DescribeConfigs(32): 0 to 4 [usable: 4],
AlterConfigs(33): 0 to 2 [usable: 2],
AlterReplicaLogDirs(34): 0 to 2 [usable: 2],
DescribeLogDirs(35): 0 to 4 [usable: 4],
SaslAuthenticate(36): 0 to 2 [usable: 2],
CreatePartitions(37): 0 to 3 [usable: 3],
CreateDelegationToken(38): 0 to 3 [usable: 3],
RenewDelegationToken(39): 0 to 2 [usable: 2],
ExpireDelegationToken(40): 0 to 2 [usable: 2],
DescribeDelegationToken(41): 0 to 3 [usable: 3],
DeleteGroups(42): 0 to 2 [usable: 2],
ElectLeaders(43): 0 to 2 [usable: 2],
IncrementalAlterConfigs(44): 0 to 1 [usable: 1],
AlterPartitionReassignments(45): 0 [usable: 0],
ListPartitionReassignments(46): 0 [usable: 0],
OffsetDelete(47): 0 [usable: 0],
DescribeClientQuotas(48): 0 to 1 [usable: 1],
AlterClientQuotas(49): 0 to 1 [usable: 1],
DescribeUserScramCredentials(50): 0 [usable: 0],
AlterUserScramCredentials(51): 0 [usable: 0],
DescribeQuorum(55): 0 to 1 [usable: 1],
AlterPartition(56): UNSUPPORTED,
UpdateFeatures(57): 0 to 1 [usable: 1],
Envelope(58): UNSUPPORTED,
DescribeCluster(60): 0 [usable: 0],
DescribeProducers(61): 0 [usable: 0],
UnregisterBroker(64): 0 [usable: 0],
DescribeTransactions(65): 0 [usable: 0],
ListTransactions(66): 0 [usable: 0],
AllocateProducerIds(67): UNSUPPORTED,
ConsumerGroupHeartbeat(68): UNSUPPORTED
)
From all the above outputs we can see that the replicas of the combined cluster is 2. That means we have successfully scaled down the replicas of the Kafka combined cluster.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete kf -n demo kafka-dev
kubectl delete kafkaopsrequest -n demo kfops-hscale-up-combined kfops-hscale-down-combined
kubectl delete ns demo
Next Steps
- Detail concepts of Kafka object.
- Different Kafka topology clustering modes here.
- Monitor your Kafka with KubeDB using out-of-the-box Prometheus operator.
- Want to hack on KubeDB? Check our contribution guidelines.