Scaling the Broker Cluster

Scale the MQTT broker cluster up, down, or to zero.

Scaling the broker cluster allows you to adjust the number of broker replicas in your Kubernetes deployment, either by adding (scaling up) or removing (scaling down) broker nodes.

Scaling the Broker Cluster Up or Down

Prerequisites

• Helm version 3 is installed on your system.

• The Kubernetes command-line tool kubectl is configured and has access to the target installation.

• You know the name and namespace of your Connectware installation. See Obtaining the name, namespace, and version of your Connectware installation.

Procedure

1. Check how many replicas are currently set for the broker StatefulSet:

kubectl get sts broker -n ${CONNECTWARE_NAMESPACE}

Example output

NAME     READY   AGE
broker   3/3     6m52s

1. Scale the StatefulSet to the desired number of replicas.

• To scale up (add brokers), increase the replica count. For example, to scale up from 2 to 3 replicas:

kubectl scale sts broker -n ${CONNECTWARE_NAMESPACE} --replicas 3

• To scale down (remove brokers), decrease the replica count. For example, to scale down from 3 to 2 replicas:

kubectl scale sts broker -n ${CONNECTWARE_NAMESPACE} --replicas 2

1. Verify that all broker nodes have formed a healthy cluster:

kubectl get pod -lapp=broker -n ${CONNECTWARE_NAMESPACE} -o name | xargs -I % kubectl exec % -- vmq-admin cluster show

Scaling Down the Broker Cluster to Zero

Prerequisites

• Helm version 3 is installed on your system.

• The Kubernetes command-line tool kubectl is configured and has access to the target installation.

• You know the name and namespace of your Connectware installation. See Obtaining the name, namespace, and version of your Connectware installation.

Procedure

1. Check how many replicas are currently set for the broker StatefulSet:

kubectl get sts broker -n ${CONNECTWARE_NAMESPACE}

Example output

NAME     READY   AGE
broker   3/3     6m52s

1. Set the number of broker replicas to zero to remove all broker pods:

kubectl scale sts broker -n ${CONNECTWARE_NAMESPACE} --replicas 0

1. Verify that all broker pods have been terminated:

kubectl get pods -n ${CONNECTWARE_NAMESPACE} -l app=broker