Zookeeper helm chart

The simple helm chart bases on an implementation of the ZooKeeper StatefulSet in kubernetes/contrib repo.

Prerequisites

To use the charts here, Helm must be installed in your Kubernetes cluster. Setting up Kubernetes and Helm and is outside the scope of this README. Please refer to the Kubernetes and Helm documentation. The versions required are:

• Helm 2.12+ - This is the earliest version of Helm tested. It is possible it works with earlier versions but this chart is untested for those versions.
• Kubernetes 1.11+ with Beta APIs enabled. This is the earliest version of Kubernetes tested. It is possible that this chart works with earlier versions but it is untested.
• Persistence volume support on underlying infrastructure
• NetworkPolicy should be enabled on a Kubernetes cluster in case if network accessibility of Zookeeper containers inside of the cluster, must be restricted by enabling cluster.networkPolicy chart parameter.

Installing the Chart

To use the charts, you must download this repository or the chart archive file and unpack it into a directory. Assuming this repository was unpacked into the directory zookeeper-helm, the chart can then be installed directly:

$ wget https://github.com/frizner/zookeeper-helm/archive/v0.1.0.tar.gz 
$ tar -zxf v0.1.0.tar.gz  
$ helm install --name zkcluster1 ./zookeeper-helm-0.1.0

As result helm should deploy realese zkcluster1 using default configuration. The configuration section lists the parameters that can be configured during the installation.

Uninstalling the Chart

To uninstall/delete the chart/zkcluster1 deployment:

$ helm delete --purge zkcluster1

The command removes all the Kubernetes components associated with the release, excluding PersistentVolumeClaim resources, and deletes the release.

Cleanup orphaned Persistent Volumes

Deleting a StateFul will not delete associated Persistent Volumes.

Do the following after deleting the chart release to clean up orphaned Persistent Volumes.

$ kubectl delete pvc -l zkcluster=zkcluster1

Configuration

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

Parameter	Description	Default
size	Number of ZooKeeper nodes in the cluster	3
podDisruptionBudget.maxUnavailable	The number of nodes that can be unavailable	1
updateStrategy.type	This feature can be used to upgrade the container images, resource requests and/or limits, labels, and annotations	RollingUpdate
image	Docker image	k8s.gcr.io/kubernetes-zookeeper:1.0-3.4.10
maxUnavailable	Number of unavailable ZooKeeper nodes in the cluster	1
imagePullPolicy	Zookeeper image pull policy	IfNotPresent
networkPolicy	If set to enabled restricts network access to server and election ports of each node by nodes of the same Zookeeper cluster. NetworkPolicy should be enabled on a Kubernetes cluster	disabled
resources	CPU/Memory resource requests/limits	Requests: 0.5/1Gi, Limits: 1/2Gi, see values.yaml
livenessProbe	A command and parameters for livenessProbe test	see values.yaml
readinessProbe	A command and parameters for readinessProbe test	see values.yaml
heap	Size of the Java Heap	512M
storage	Size of a persist volume for the each Zookeeper node	10Gi
logLevel	Level of logging	INFO
clientPort	Client port	2181
serverPort	Server follower port	2888
leadElectionPort	Leader election port	3888
user	User ID to start Zookeeper process	1000
group	Group ID to start Zookeeper process	1000
initLimit	Amount of time, in ticks, to allow followers to connect and sync to a leader.	1
tickTime	The length of a single tick, milliseconds	2000
maxClientCnxns	Limits the number of concurrent connections (at the socket level) that a single client, identified by IP address, may make to a single member of the ZooKeeper ensemble.	60
snapRetainCount	When enabled, ZooKeeper auto purge feature retains the autopurge.snapRetainCount most recent snapshots and the corresponding transaction logs in the dataDir and dataLogDir respectively and deletes the rest.	3
purgeInterval	The time interval in hours for which the purge task has to be triggered.	12
maxSessionTimeout	The maximum session timeout in milliseconds that the server will allow the client to negotiate.	40000
minSessionTimeout:	The minimum session timeout in milliseconds that the server will allow the client to negotiate.	4000

Specify each parameter using the --set key=value[,key=value] argument to helm install.

Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,

$ helm install --name zkcluster1 -f values.yaml ./zookeeper-helm

Tip: You can use the default values.yaml