ksqldb

ksqlDB

A Helm chart for ksqlDB on Kubernetes

Introduction

This chart bootstraps a ksqlDB.

ksqlDB is an event streaming database purpose-built to help developers create stream processing applications on top of Apache Kafka.

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
ksqlDB	v0.28.2

Installing the Chart

Add the chart repository, if not done before:

helm repo add rhcharts https://ricardo-aires.github.io/helm-charts/

By default this chart is set to use the umbrella chart kstack, but can be run against an external Kafka, Schema Registry and Kafka Connect by passing:

helm install --set kafka.enabled=false --set kafka.bootstrapServers=PLAINTEXT://kstack-kafka-headless.default:9092 --set schema-registry.enabled=false --set schema-registry.url=kstack-schema-registry.default:8081 --set kafka-connect.enabled=false --set kafka-connect.url=kstack-kafka-connect.default:8083 ktool rhcharts/ksqldb
NAME: ktool
LAST DEPLOYED: Tue Mar 23 18:35:37 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
** Please be patient while the ksqldb chart is being deployed in release ktool **

This chart bootstraps a ksqldb that can be accessed from within your cluster:

    ktool-ksqldb.default:8088

$

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

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

To uninstall the ktool deployment run:

helm uninstall ktool

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

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 install ktool -f my-values.yaml rhcharts/ksqldb

A default values.yaml is available and should be checked for more advanced usage.

Image

By default the confluentinc/ksqldb-server is in use.

Parameter	Description	Default
image.registry	Registry used to distribute the Docker Image.	docker.io
image.repository	Docker Image of ksqlDB.	confluentinc/ksqldb-server
image.tag	Docker Image Tag of ksqlDB.	0.28.2

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.

ksqlDB Configuration

Deploying ksqlDB in headless mode

ksqlDB supports locked-down, "headless" deployment scenarios where interactive use of the ksqlDB cluster is disabled. For example, the CLI enables a team of users to develop and verify their queries interactively on a shared testing ksqlDB cluster. But when you deploy these queries in your production environment, you want to lock down access to ksqlDB servers, version-control the exact queries, and store them in a .sql file. This prevents users from interacting directly with the production ksqlDB cluster. For more information, see Headless Deployment.

To enable headless mode in this chart, simply pass the name of a ConfiMap containing the sql script file:

Parameter	Description	Default
queriesFileConfigMap	Name of the ConfigMap that stores the queries.sql script with all the ksql queries for a given use case	nil

Ports used by ksqlDB

By default the Service will expose the pods in the port 8088, port.

Enable Kerberos

This chart is prepared to enable Kerberos authentication in Kafka

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
serviceName	Primary of the Principal (user, service, host)
domain	REALM of the Principal	nil

¹ When kerberos.enabled these parameters are required, and the ConfigMap and Secret need to exist beforehand.

Resources for Containers

Regarding the management of Resources for Containers the next defaults regarding requests and limits are set:

Parameter	Description	Default
resources.limits.cpu	a container cannot use more CPU than the configured limit	1
resources.limits.memory	a container cannot use more Memory than the configured limit	3000Mi
resources.requests.cpu	a container is guaranteed to be allocated as much CPU as it requests	250m
resources.requests.memory	a container is guaranteed to be allocated as much Memory as it requests	1000Mi

In terms of the JVM the next default is set:

Parameter	Description	Default
heapOpts	The JVM Heap Options for ksqlDB.	"-XX:MaxRAMPercentage=50.0 -XX:InitialRAMPercentage=50.0"

Advance Configuration

Check the values.yaml for more advance configuration such as:

• Liveness and Readiness Probes
• Pod Security Context
• Container Security Context
• Create a pod that gets scheduled to your chosen node