bitnamicharts/zookeeper

Bitnami Secure Images Helm chart for Apache ZooKeeper

Apache ZooKeeper provides a reliable, centralized register of configuration data and services for distributed applications.

Overview of Apache ZooKeeper

Trademarks: This software listing is packaged by Bitnami. The respective trademarks mentioned in the offering are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

TL;DR

console
helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/zookeeper

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository.

Introduction

This chart bootstraps a https://github.com/bitnami/containers/tree/main/bitnami/zookeeper deployment on a Kubernetes cluster using the Helm package manager.

Before you begin

• Kubernetes 1.23+
• Helm 3.8.0+
• PV provisioner support in the underlying infrastructure

Installing the Chart

To install the chart with the release name my-release:

console
helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/zookeeper

Note: You need to substitute the placeholders REGISTRY_NAME and REPOSITORY_NAME with a reference to your Helm chart registry and repository. For example, in the case of Bitnami, you need to use REGISTRY_NAME=registry-1.docker.io and REPOSITORY_NAME=bitnamicharts.

These commands deploy ZooKeeper on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.

Tip: List all releases using helm list

Configuration and installation details

This section describes credentials, configuration, and other installation options.

Resource requests and limits

Bitnami charts allow setting resource requests and limits for all containers inside the chart deployment. These are inside the resources value (check parameter table). Setting requests is essential for production workloads and these should be adapted to your specific use case.

To make this process easier, the chart contains the resourcesPreset values, which automatically sets the resources section according to different presets. Check these presets in https://github.com/bitnami/charts/blob/main/bitnami/common/templates/_resources.tpl#L15. However, in production workloads using resourcesPreset is discouraged as it may not fully adapt to your specific needs. Find more information on container resource management in the official Kubernetes documentation.

Update credentials

Bitnami charts configure credentials at first boot. Any further change in the secrets or credentials require manual intervention. Follow these instructions:

• Update the user password following the upstream documentation
• Update the password secret with the new values (replace the SECRET_NAME, CLIENT_PASSWORD and SERVER_PASSWORD placeholders)

shell
kubectl create secret generic SECRET_NAME --from-literal=client-password=CLIENT_PASSWORD --from-literal=server-password=SERVER_PASSWORD --dry-run -o yaml | kubectl apply -f -

Prometheus metrics

This chart can be integrated with Prometheus by setting metrics.enabled to true. This will expose Zookeeper native Prometheus endpoint and a metrics service configurable under the metrics.service section. It will have the necessary annotations to be automatically scraped by Prometheus.

Prometheus requirements

It is necessary to have a working installation of Prometheus or Prometheus Operator for the integration to work. Install the https://github.com/bitnami/charts/tree/main/bitnami/prometheus or the https://github.com/bitnami/charts/tree/main/bitnami/kube-prometheus to easily have a working Prometheus in your cluster.

Integration with Prometheus Operator

The chart can deploy ServiceMonitor objects for integration with Prometheus Operator installations. To do so, set the value metrics.serviceMonitor.enabled=true. Ensure that the Prometheus Operator CustomResourceDefinitions are installed in the cluster or it will fail with the following error:

text
no matches for kind "ServiceMonitor" in version "monitoring.coreos.com/v1"

Install the https://github.com/bitnami/charts/tree/main/bitnami/kube-prometheus for having the necessary CRDs and the Prometheus Operator.

Rolling vs Immutable tags

It is strongly recommended to use immutable tags in a production environment. This ensures your deployment does not change automatically if the same tag is updated with a different image.

Bitnami will release a new chart updating its containers if a new version of the main container, significant changes, or critical vulnerabilities exist.

Configure log level

You can configure the ZooKeeper log level using the ZOO_LOG_LEVEL environment variable or the parameter logLevel. By default, it is set to ERROR because each use of the liveness probe and the readiness probe produces an INFO message on connection and a WARN message on disconnection, generating a high volume of noise in your logs.

In order to remove that log noise so levels can be set to 'INFO', two changes must be made.

First, ensure that you are not getting metrics via the deprecated pattern of polling mntr on the ZooKeeper client port. The preferred method of polling for Apache ZooKeeper metrics is the ZooKeeper metrics server. This is supported in this chart when setting metrics.enabled to true.

Second, to avoid the connection/disconnection messages from the probes, you can set custom values for these checks which direct them to the ZooKeeper Admin Server instead of the client port. By default, an Admin Server will be started that listens on localhost at port 8080. The following is an example of this use of the Admin Server for probes:

yaml
livenessProbe:
  enabled: false
readinessProbe:
  enabled: false
customLivenessProbe:
  exec:
    command: ['/bin/bash', '-c', 'curl -s -m 2 http://localhost:8080/commands/ruok | grep ruok']
  initialDelaySeconds: 30
  periodSeconds: 10
  timeoutSeconds: 5
  successThreshold: 1
  failureThreshold: 6
customReadinessProbe:
  exec:
    command: ['/bin/bash', '-c', 'curl -s -m 2 http://localhost:8080/commands/ruok | grep error | grep null']
  initialDelaySeconds: 5
  periodSeconds: 10
  timeoutSeconds: 5
  successThreshold: 1
  failureThreshold: 6

You can also set the log4j logging level and what log appenders are turned on, by using ZOO_LOG4J_PROP set inside of conf/log4j.properties as zookeeper.root.logger by default to

console
zookeeper.root.logger=INFO, CONSOLE

The available appenders are:

• CONSOLE
• ROLLINGFILE
• RFAAUDIT
• TRACEFILE

Backup and restore

To back up and restore Helm chart deployments on Kubernetes, you need to back up the persistent volumes from the source deployment and attach them to a new deployment using Velero, a Kubernetes backup/restore tool. Find the instructions for using Velero in this guide.

FIPS parameters

The FIPS parameters only have effect if you are using images from the Bitnami Secure Images catalog.

For more information on this new support, please refer to the FIPS Compliance section.

Persistence

The https://github.com/bitnami/containers/tree/main/bitnami/zookeeper image stores the ZooKeeper data and configurations at the /bitnami/zookeeper path of the container.

Persistent Volume Claims are used to keep the data across deployments. This is known to work in GCE, AWS, and minikube. See the Parameters section to configure the PVC or to disable persistence.

If you encounter errors when working with persistent volumes, refer to our troubleshooting guide for persistent volumes.

Adjust permissions of persistent volume mountpoint

As the image run as non-root by default, it is necessary to adjust the ownership of the persistent volume so that the container can write data into it.

By default, the chart is configured to use Kubernetes Security Context to automatically change the ownership of the volume. However, this feature does not work in all Kubernetes distributions. As an alternative, this chart supports using an initContainer to change the ownership of the volume before mounting it in the final destination.

You can enable this initContainer by setting volumePermissions.enabled to true.

Configure the data log directory

You can use a dedicated device for logs (instead of using the data directory) to help avoiding competition between logging and snaphots. To do so, set the dataLogDir parameter with the path to be used for writing transaction logs. Alternatively, set this parameter with an empty string and it will result in the log being written to the data directory (Zookeeper's default behavior).

When using a dedicated device for logs, you can use a PVC to persist the logs. To do so, set persistence.enabled to true. See the Persistence Parameters section for more information.

Set pod affinity

This chart allows you to set custom pod affinity using the affinity parameter. Find more information about pod affinity in the Kubernetes documentation.

As an alternative, you can use any of the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the https://github.com/bitnami/charts/tree/main/bitnami/common#affinities chart. To do so, set the podAffinityPreset, podAntiAffinityPreset, or nodeAffinityPreset parameters.

Parameters

The following subsections list global, common, and component-specific parameters.

Global parameters

Common parameters

ZooKeeper chart parameters

_Note: the README for this chart is longer than the DockerHub length limit of 25000, so it has been trimmed. The full README can be found at [***]