zookeeper

Zookeeper Helm Chart

Installs Zookeeper clusters atop Kubernetes.

Introduction

This chart creates a Zookeeper cluster in Kubernetes using the Helm package manager. The chart can be installed multiple times to create Zookeeper cluster in multiple namespaces.

Prerequisites

• Kubernetes 1.15+ with Beta APIs
• Helm 3.2.1+
• Zookeeper Operator. You can install it using its own Helm chart

Installing the Chart

To install the zookeeper chart, use the following commands:

$ helm repo add pravega https://charts.pravega.io
$ helm repo update
$ helm install [RELEASE_NAME] pravega/zookeeper --version=[VERSION]

where:

• [RELEASE_NAME] is the release name for the zookeeper chart.
• [CLUSTER_NAME] is the name of the zookeeper cluster so created. (If [RELEASE_NAME] contains the string zookeeper, [CLUSTER_NAME] = [RELEASE_NAME], else [CLUSTER_NAME] = [RELEASE_NAME]-zookeeper. The [CLUSTER_NAME] can however be overridden by providing --set fullnameOverride=[CLUSTER_NAME] along with the helm install command)
• [VERSION] can be any stable release version for zookeeper from 0.2.8 onwards.

This command deploys zookeeper on the Kubernetes cluster in its default configuration. The configuration section lists the parameters that can be configured during installation.

Upgrading the Chart

To upgrade the zookeeper chart from version [OLD_VERSION] to version [NEW_VERSION], use the following command:

$ helm upgrade [RELEASE_NAME] pravega/zookeeper --version=[NEW_VERSION] --set image.tag=[NEW_VERSION] --reuse-values --timeout 600s

Note: By specifying the --reuse-values option, the configuration of all parameters are retained across upgrades. However if some values need to be modified during the upgrade, the --set flag can be used to specify the new configuration for these parameters. Also, by skipping the reuse-values flag, the values of all parameters are reset to the default configuration that has been specified in the published charts for version [NEW_VERSION].

Uninstalling the Chart

To uninstall/delete the zookeeper chart, use the following command:

$ helm uninstall [RELEASE_NAME]

This command removes all the Kubernetes components associated with the chart and deletes the release.

Configuration

The following table lists the configurable parameters of the zookeeper chart and their default values.

Parameter	Description	Default
replicas	Expected size of the zookeeper cluster (valid range is from 1 to 7)	3
maxUnavailableReplicas	Max unavailable replicas in pdb	1
triggerRollingRestart	If true, the zookeeper cluster is restarted. After the restart is triggered, this value is auto-reverted to false.	false
image.repository	Image repository	pravega/zookeeper
image.tag	Image tag	0.2.14
image.pullPolicy	Image pull policy	IfNotPresent
domainName	External host name appended for dns annotation
kubernetesClusterDomain	Domain of the kubernetes cluster	cluster.local
probes.readiness.initialDelaySeconds	Number of seconds after the container has started before readiness probe is initiated	10
probes.readiness.periodSeconds	Number of seconds in which readiness probe will be performed	10
probes.readiness.failureThreshold	Number of seconds after which the readiness probe times out	3
probes.readiness.successThreshold	Minimum number of consecutive successes for the readiness probe to be considered successful after having failed	1
probes.readiness.timeoutSeconds	Number of times Kubernetes will retry after a readiness probe failure before restarting the container	10
probes.liveness.initialDelaySeconds	Number of seconds after the container has started before liveness probe is initiated	10
probes.liveness.periodSeconds	Number of seconds in which liveness probe will be performed	10
probes.liveness.failureThreshold	Number of seconds after which the liveness probe times out	3
probes.liveness.timeoutSeconds	Number of times Kubernetes will retry after a liveness probe failure before restarting the container	10
labels	Specifies the labels to be attached	{}
ports	Groups the ports for a zookeeper cluster node for easy access	[]
pod	Defines the policy to create new pods for the zookeeper cluster	{}
pod.labels	Labels to attach to the pods	{}
pod.nodeSelector	Map of key-value pairs to be present as labels in the node in which the pod should run	{}
pod.affinity	Specifies scheduling constraints on pods	{}
pod.resources	Specifies resource requirements for the container	{}
pod.tolerations	Specifies the pod's tolerations	[]
pod.env	List of environment variables to set in the container	[]
pod.annotations	Specifies the annotations to attach to pods	{}
pod.securityContext	Specifies the security context for the entire pod	{}
pod.terminationGracePeriodSeconds	Amount of time given to the pod to shutdown normally	30
pod.serviceAccountName	Name for the service account	zookeeper
pod.imagePullSecrets	ImagePullSecrets is a list of references to secrets in the same namespace to use for pulling any images.	[]
clientService	Defines the policy to create client Service for the zookeeper cluster.	{}
clientService.annotations	Specifies the annotations to attach to client Service the operator creates.	{}
headlessService	Defines the policy to create headless Service for the zookeeper cluster.	{}
headlessService.annotations	Specifies the annotations to attach to headless Service the operator creates.	{}
adminServerService	Defines the policy to create AdminServer Service for the zookeeper cluster.	{}
adminServerService.annotations	Specifies the annotations to attach to AdminServer Service the operator creates.	{}
adminServerService.external	Specifies if LoadBalancer should be created for the AdminServer. True means LoadBalancer will be created, false - only ClusterIP will be used.	false
config.initLimit	Amount of time (in ticks) to allow followers to connect and sync to a leader	10
config.tickTime	Length of a single tick which is the basic time unit used by Zookeeper (measured in milliseconds)	2000
config.syncLimit	Amount of time (in ticks) to allow followers to sync with Zookeeper	2
config.globalOutstandingLimit	Max limit for outstanding requests	1000
config.preAllocSize	PreAllocSize in kilobytes	65536
config.snapCount	The number of transactions recorded in the transaction log before a snapshot can be taken	100000
config.commitLogCount	The number of committed requests in memory	500
config.snapSizeLimitInKb	SnapSizeLimitInKb	4194304
config.maxCnxns	The total number of concurrent connections that can be made to a zookeeper server	0
config.maxClientCnxns	The number of concurrent connections that a single client	60
config.minSessionTimeout	The minimum session timeout in milliseconds that the server will allow the client to negotiate	4000
config.maxSessionTimeout	The maximum session timeout in milliseconds that the server will allow the client to negotiate	40000
config.autoPurgeSnapRetainCount	The number of snapshots to be retained	3
config.autoPurgePurgeInterval	The time interval in hours for which the purge task has to be triggered	1
config.quorumListenOnAllIPs	Whether Zookeeper server will listen for connections from its peers on all available IP addresses	false
config.additionalConfig	Additional zookeeper coniguration parameters that should be defined in generated zoo.cfg file	{}
storageType	Type of storage that can be used it can take either ephemeral or persistence as value	persistence
persistence.reclaimPolicy	Reclaim policy for persistent volumes	Delete
persistence.annotations	Specifies the annotations to attach to pvcs	{}
persistence.storageClassName	Storage class for persistent volumes	``
persistence.volumeSize	Size of the volume requested for persistent volumes	20Gi
ephemeral.emptydirvolumesource.medium	What type of storage medium should back the directory.	""
ephemeral.emptydirvolumesource.sizeLimit	Total amount of local storage required for the EmptyDir volume.	20Gi
containers	Application containers run with the zookeeper pod	[]
initContainers	Init Containers to add to the zookeeper pods	[]
volumes	Named volumes that may be accessed by any container in the pod	[]
volumeMounts	Customized volumeMounts for zookeeper container that can be configured to mount volumes to zookeeper container	[]