When the traffic handled by your Pulsar cluster increases or decreases, you can scale out or scale in the cluster accordingly. Depending on the specific use case, you may choose to increase or decrease the number of nodes for different components, including Pulsar brokers, Pulsar proxies, bookies, and ZooKeeper. When resizing the Pulsar cluster on Kubernetes created by the Pulsar Operators, you need to perform the scaling action on Custom Resources (CRs) instead of the individual workloads deployed through them. For example, when deploying Pulsar broker workloads, the Pulsar Operators create a broker StatefulSet with 2 Pod replicas by default. To scale the StatefulSet, you should adjust the broker CR instead of manually changing the StatefulSet. This document describes how to manually scale Pulsar components on Kubernetes.

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Prerequisites

You have deployed a Pulsar cluster using the Pulsar Operators.

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Scale Pulsar brokers

If you use the default broker CR, you should have 2 broker replicas running in the pulsar namespace. This example scales the number of Pods from 2 to 5.
  1. View the existing broker CR. 
    kubectl get pb -n pulsar
    You should see the following output: 
    NAME     REPLICAS   READY REPLICAS   DESIRED IMAGE                            ENDPOINT   AGE
brokers  2          2                streamnative/sn-platform-slim:2.10.3.4              10m
  2. Run the following command to scale brokers. 
    kubectl scale pb brokers --replicas=5 -n pulsar
  3. View the newly-created Pods. 
    kubectl get pods -n pulsar
    You should see the following output: 
    NAME                         READY   STATUS    RESTARTS   AGE
bookies-bk-0                 1/1     Running   0          10m
bookies-bk-1                 1/1     Running   0          10m
bookies-bk-2                 1/1     Running   0          10m
bookies-bk-auto-recovery-0   1/1     Running   0          10m
brokers-broker-0             1/1     Running   0          10m
brokers-broker-1             1/1     Running   0          10m
brokers-broker-2             1/1     Running   0          10s
brokers-broker-3             1/1     Running   0          10s
brokers-broker-4             1/1     Running   0          10s
proxys-proxy-0               1/1     Running   0          10m
proxys-proxy-1               1/1     Running   0          10m
zookeepers-zk-0              1/1     Running   0          10m
zookeepers-zk-1              1/1     Running   0          10m
zookeepers-zk-2              1/1     Running   0          10m
  4. Alternatively, you can create a broker YAML file with the following configuration and use the kubectl apply -f command to apply the file. 
    apiVersion: pulsar.streamnative.io/v1alpha1
kind: PulsarBroker
metadata:
name: brokers
namespace: pulsar
spec:
image: streamnative/sn-platform-slim:2.10.3.4
pod:
  resources:
    requests:
    cpu: 200m
    memory: 512Mi
  securityContext:
    runAsNonRoot: true
replicas: 5 # Change the replica count
zkServers: zookeepers-zk:2181

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Scale Pulsar proxies

If you use the default proxy CR, you should have 2 proxy replicas running in the pulsar namespace. This example scales the number of Pods from 2 to 5.
  1. View the existing proxy CR. 
    kubectl get pp -n pulsar
    You should see the following output: 
    NAME     REPLICAS   READY REPLICAS   DESIRED IMAGE                            ENDPOINT   AGE
proxys   2          2                streamnative/sn-platform-slim:2.10.3.4              10m
  2. Run the following command to scale Pulsar proxies. 
    kubectl scale pp proxys --replicas=5 -n pulsar
  3. View the newly created Pods. 
    kubectl get pods -n pulsar
    You should see the following output: 
    NAME                         READY   STATUS    RESTARTS   AGE
bookies-bk-0                 1/1     Running   0          10m
bookies-bk-1                 1/1     Running   0          10m
bookies-bk-2                 1/1     Running   0          10m
bookies-bk-auto-recovery-0   1/1     Running   0          10m
brokers-broker-0             1/1     Running   0          10m
brokers-broker-1             1/1     Running   0          10m
proxys-proxy-0               1/1     Running   0          10m
proxys-proxy-1               1/1     Running   0          10m
proxys-proxy-2               1/1     Running   0          42s
proxys-proxy-3               1/1     Running   0          42s
proxys-proxy-4               1/1     Running   0          42s
zookeepers-zk-0              1/1     Running   0          10m
zookeepers-zk-1              1/1     Running   0          10m
zookeepers-zk-2              1/1     Running   0          10m
  4. Alternatively, you can create a proxy YAML file with the following configuration and use the kubectl apply -f command to apply the file. 
    apiVersion: pulsar.streamnative.io/v1alpha1
kind: PulsarProxy
metadata:
name: proxys
namespace: pulsar
spec:
image: 'streamnative/sn-platform-slim:2.10.3.4'
pod:
  resources:
    requests:
    cpu: 200m
    memory: 512Mi
  securityContext:
    runAsNonRoot: true
brokerAddress: brokers-broker
replicas: 5 # Change the replica count
config:
  tls:
    enabled: false
dnsNames: []
issuerRef:
  name: ''

​
Scale bookies

If you use the default BookKeeper CR, you should have 3 bookie replicas running in the pulsar namespace. This example scales the number of bookie Pods from 3 to 7.
  1. View the existing BookKeeper CR. 
    kubectl get bk -n pulsar
    You should see the following output: 
    NAME      REPLICAS   READY REPLICAS   ZKSERVERS            DESIRED IMAGE                            AGE
bookies   3          3                zookeepers-zk:2181   streamnative/sn-platform-slim:2.10.3.4   13m
  2. Run the following command to scale bookies. 
    kubectl scale bk bookies --replicas=7 -n pulsar
  3. View the newly-created Pods. 
    kubectl get pods -n pulsar
    You should see the following output: 
    NAME                         READY   STATUS    RESTARTS   AGE
bookies-bk-0                 1/1     Running   0          10m
bookies-bk-1                 1/1     Running   0          10m
bookies-bk-2                 1/1     Running   0          10m
bookies-bk-3                 1/1     Running   0          40s
bookies-bk-4                 1/1     Running   0          40s
bookies-bk-5                 1/1     Running   0          40s
bookies-bk-6                 1/1     Running   0          40s
bookies-bk-auto-recovery-0   1/1     Running   0          10m
brokers-broker-0             1/1     Running   0          10m
brokers-broker-1             1/1     Running   0          10m
proxys-proxy-0               1/1     Running   0          10m
proxys-proxy-1               1/1     Running   0          10m
zookeepers-zk-0              1/1     Running   0          10m
zookeepers-zk-1              1/1     Running   0          10m
zookeepers-zk-2              1/1     Running   0          10m
  4. Alternatively, you can create a BookKeeper YAML file with the following configuration and use the kubectl apply -f command to apply the file. 
    apiVersion: bookkeeper.streamnative.io/v1alpha1
kind: BookKeeperCluster
metadata:
name: bookies
namespace: pulsar
spec:
image: streamnative/sn-platform-slim:2.10.3.4
replicas: 7 # Change the replica count
pod:
  resources:
    requests:
    cpu: 200m
    memory: 512Mi
  securityContext:
    runAsNonRoot: true
storage:
  journal:
    numDirsPerVolume: 1
    numVolumes: 1
    volumeClaimTemplate:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 8Gi
  ledger:
    numDirsPerVolume: 1
    numVolumes: 1
    volumeClaimTemplate:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 16Gi
  reclaimPolicy: Delete
zkServers: zookeepers-zk:2181

​
Scale ZooKeeper

If you use the default ZooKeeper CR, you should have 3 ZooKeeper replicas running in the pulsar namespace. This example scales the number of Pods from 3 to 5.
  1. View the existing ZooKeeper CR. 
    kubectl get zk -n pulsar
    You should see the following output: 
    NAME         REPLICAS   READY REPLICAS   DESIRED IMAGE                            AGE
zookeepers   3          3                streamnative/sn-platform-slim:2.10.3.4   16m
  2. Run the following command to scale ZooKeeper. 
    kubectl scale zk zookeepers --replicas=5 -n pulsar
  3. View the newly-created Pods. 
    kubectl get pods -n pulsar
    You should see the following output: 
    NAME                         READY   STATUS    RESTARTS   AGE
bookies-bk-0                 1/1     Running   0          10m
bookies-bk-1                 1/1     Running   0          10m
bookies-bk-2                 1/1     Running   0          10m
bookies-bk-auto-recovery-0   1/1     Running   0          10m
brokers-broker-0             1/1     Running   0          10m
brokers-broker-1             1/1     Running   0          10m
proxys-proxy-0               1/1     Running   0          10m
proxys-proxy-1               1/1     Running   0          10m
zookeepers-zk-0              1/1     Running   0          54s
zookeepers-zk-1              1/1     Running   0          31s
zookeepers-zk-2              1/1     Running   0          71s
zookeepers-zk-3              1/1     Running   0          98s
zookeepers-zk-4              1/1     Running   0          98s
  4. Alternatively, you can create a ZooKeeper YAML file with the following configuration and use the kubectl apply -f command to apply the file. 
    apiVersion: zookeeper.streamnative.io/v1alpha1
kind: ZooKeeperCluster
metadata:
name: zookeepers
namespace: pulsar
spec:
image: streamnative/sn-platform-slim:2.10.3.4
pod:
  resources:
    requests:
    cpu: 50m
    memory: 256Mi
  securityContext:
    runAsNonRoot: true
persistence:
  data:
    accessModes:
      - ReadWriteOnce
    resources:
    requests:
      storage: 8Gi
  dataLog:
    accessModes:
      - ReadWriteOnce
    resources:
    requests:
      storage: 2Gi
  reclaimPolicy: Delete
replicas: 5 # Change the replica count