helm-charts
zookeeper
A Helm chart for Confluent Zookeeper on Kubernetes
Introduction
This chart bootstraps an ensemble Apache Zookeeper Servers using the Confluent stable version.
ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services, used as a backend by distributed applications.
Developing Environment
| component | version |
|---|---|
| Podman | v4.3.1 |
| Minikube | v1.28.0 |
| Kubernetes | v1.25.3 |
| Helm | v3.10.2 |
| Confluent Platform | v7.3.0 |
| Zookeeper | v3.6.3 |
Installing the Chart
Add the chart repository, if not done before:
helm repo add rhcharts https://ricardo-aires.github.io/helm-charts/
To install the chart with the release name zkp:
$ helm upgrade --install zkp rhcharts/zookeeper
Release "zkp" does not exist. Installing it now.
NAME: zkp
LAST DEPLOYED: Mon Nov 21 15:49:17 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
** Please be patient while the zookeeper chart is being deployed in release zkp **
This chart bootstraps an ensemble Apache Zookeeper Servers made of "3" servers using the Confluent stable version that can be accessed from within your cluster:
zkp-zookeeper-headless.default:2181
To connect to your ZooKeeper server run the following commands:
$ kubectl exec -it -n default zkp-zookeeper-0 -- zookeeper-shell zkp-zookeeper-headless.default:2181
More info:
https://ricardo-aires.github.io/helm-charts/charts/zookeeper/
$
This command deploy ZooKeeper on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.
The chart will create the next resources:
- A PodDisruptionBudget to ensure service availability during planned maintenance.
- A Headless Service to control the network domain for the ZooKeeper processes and to expose the AdminServer.
- A StatefulSet which contains 3 Zookeeper Pods, by default.
One can run the:
- helm list command to list releases installed
- helm status to display the status of the named release
- helm test to run tests for a release
This chart uses the srvr command of the Zookeeper Four Letter Words to check that every Zookeeper Server is responding.
To uninstall the zkp deployment run:
helm uninstall zkp
The command removes all the Kubernetes components associated with the chart and deletes the release.
Keep in mind that the PersistentVolumeClaims are in retain.
Parameters
You can 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 upgrade --install zkp -f my-values.yaml rhcharts/zookeeper
A default values.yaml is available and should be checked for more advanced usage.
Image
By default the confluentinc/cp-zookeeper is in use.
| Parameter | Description | Default |
|---|---|---|
image.registry |
Registry used to distribute the Docker Image. | docker.io |
image.repository |
Docker Image of Confluent Zookeeper. | confluentinc/cp-zookeeper |
image.tag |
Docker Image Tag of Confluent Zookeeper. | 7.3.0 |
One can easily change the image.tag to use another version. When using a local/proxy docker registry we must change image.registry as well.
Zookeeper Ensemble
The configuration parameters in this section control the resources requested and utilized by the zookeeper chart.
| Parameter | Description | Default |
|---|---|---|
replicaCount |
The number of ZooKeeper servers. | 3 |
A minimum of three servers are required for a fault tolerant clustered setup, and it is strongly recommended that you have an odd number of servers, because Zookeeper requires a majority.
The value for the PodDisruptionBudget is calculated automatically from the given
replicaCount.
Confluent Zookeeper Configuration
The next configuration related to Zookeeper are available:
| Parameter | Description | Default |
|---|---|---|
tickTime |
The length of a single tick, which is the basic time unit used by ZooKeeper, as measured in milliseconds. | 2000 |
initLimit |
Amount of time, in ticks (see tickTime), to allow followers to connect and sync to a leader. |
10 |
syncLimit |
Amount of time, in ticks (see tickTime), to allow followers to sync with ZooKeeper. |
5 |
maxClientCnxns |
Limits the number of concurrent connections that a single client may make to a single member of the ZooKeeper ensemble. | 60 |
autopurge.purgeInterval |
The time interval in hours for which the purge task has to be triggered. | 24 |
autopurge.snapRetainCount |
umber of most recent snapshots and the corresponding transaction logs in the dataDir and dataLogDir to keep. | 3 |
quorumListenOnAllIPs |
When set to true the ZooKeeper server will listen for connections from its peers on all available IP addresses | true |
maxSessionTimeout |
The maximum session timeout in milliseconds that the server will allow the client to negotiate. | 40000 |
adminEnableServer |
Flag for the AdminServer | true |
log4jRootLogLevel |
Log level of ZooKeeper server | INFO |
More information can be found in the Apache Zookeeper Documentation and in the Confluent Documentation.
Ports used by Zookeeper
ZooKeeper default ports:
| Parameter | Description | Default |
|---|---|---|
port.peers |
The port on which the ZooKeeper servers listen for requests from other servers in the ensemble. | 2888 |
port.leader |
The port on which the ZooKeeper servers perform leader election. | 3888 |
port.client |
The port to listen for client connections; that is, the port that clients attempt to connect to. | 2181 |
Since 3.5.0 we may also set the AdminServer which by default listens in the 8080 port but can be changed by setting the port.admin in the AdminServer configuration.
Enable Kerberos
This chart is prepared to enable Kerberos authentication in Zookeeper
| Parameter | Description | Default |
|---|---|---|
kerberos.enabled |
Boolean to control if Kerberos is enabled. | false |
kerberos.krb5Conf |
Name of the ConfigMap that stores the krb5.conf, Kerberos Configuration file |
nil¹ |
kerberos.keyTabSecret |
Name of the Secret that stores the Keytab | nil¹ |
kerberos.jaasConf |
Name of the ConfigMap that stores the JAAS configuration files per host. | nil¹ |
¹ When
kerberos.enabledthese parameters are required, and the ConfigMap and Secret need to exist before.
Data Persistence
The ZooKeeper server continually saves znode snapshot files in a Data Directory to enable you to recover data, transactional logs in this deployment are store in a separated directory.
| Parameter | Description | Default |
|---|---|---|
data.storageClass |
Valid options: nil, "-", or storage class name. |
nil |
data.storageSize |
Size for data dir. | 1Gi |
This will allow the creation of two Persistent Volume using a specific Storage Class and the same size for both.
Resources for Containers
Regarding the management of Resources for Containers the next defaults regarding resources and limits are set:
| Parameter | Description | Default |
|---|---|---|
resources.limits.cpu |
a container cannot use more CPU than the configured limit | 200m |
resources.limits.memory |
a container cannot use more Memory than the configured limit | 650Mi |
resources.requests.cpu |
a container is guaranteed to be allocated as much CPU as it requests | 100m |
resources.requests.memory |
a container is guaranteed to be allocated as much Memory as it requests | 320Mi |
In terms of the JVM the next default is set:
| Parameter | Description | Default |
|---|---|---|
heapOpts |
The JVM Heap Options for Zookeeper Server. | "-XX:MaxRAMPercentage=75.0 -XX:InitialRAMPercentage=50.0" |
Advance Configuration
Check the values.yaml for more advance configuration such as: