Kubernetes

The Stackable Data Platform runs on Kubernetes, a Kubernetes cluster is a prerequisite to running the platform. On this page you will find information on the supported Kubernetes distributions for production as well as how to set up a local test installation to try out parts of the platform right away.

Supported production distributions

The Stackable Data Platform requires a Kubernetes cluster to be present, where you can install things into. How to set up Kubernetes as well as a cluster depends on the distribution you chose.

The following distributions are supported for a production setup of the Stackable Data Platform:

In this version of the SDP, the following Kubernetes versions are supported:

  • 1.28

  • 1.27

  • 1.26

Consult the release notes to find out which specific versions are supported for the Stackable Data Platform you are using.

Notes on OpenShift

SDP operators are certified for the OpenShift platform and can be installed from the OperatorHub.

Install the SDP operators in a namespace/project called stackable-operators. Installing the operators anywhere else may lead to unwanted effects or even faulty installations. This restriction is caused by limitations in the Operator Bundle Format (OPM) used by OpenShift.

Customizing operator installations

Depending on the cluster size, you may need to customize the resources requested by the SDP operator Pods. This is possible when installing the operators from the command line. For example, to assign 256Mi of memory to the Apache Kafka operator, you need to create a custom Subscription as follows:

---
apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: stackable-kafka-operator
  namespace: stackable-operators
spec:
  channel: stable
  installPlanApproval: Automatic
  name: stackable-kafka-operator
  source: certified-operators
  sourceNamespace: openshift-marketplace
  startingCSV: kafka-operator.v23.11.0
  config:
    resources:
      limits:
        memory: 256Mi
      requests:
        memory: 256Mi

In addition, You can restrict the operator to watch a specific namespace. By default, the operator watches all namespaces. For example, to restrict the Kafka operator to watching only a namespace called kafka-namespace you add the following properties to the Subscription manifest:

spec:
  config:
    env:
      - name: WATCH_NAMESPACE
        value: kafka-namespace

Installing a testinging/development Kubernetes instance locally

Stackable’s control plane is built around Kubernetes, and we’ll give some brief examples of how to install Kubernetes on your machine.

Installing kubectl

Stackable operators and their services are managed by applying manifest files to the Kubernetes cluster. For this purpose, you need to have the kubectl tool installed. Follow the instructions here for your platform.

Installing Kubernetes using Kind

Kind offers a very quick and easy way to bootstrap your Kubernetes infrastructure in Docker. The big advantage of this is that you can simply remove the Docker containers when you’re finished and clean up easily, making it great for testing and development.

If you don’t already have Docker then visit Docker Website to find out how to install Docker. Kind is a single executable that performs the tasks of installing and configuring Kubernetes for you within Docker containers. The Kind Website has instructions for installing Kind on your system.

Once you have both of these installed then you can build a Kubernetes cluster in Docker. We’re going to create a simple, single node cluster to test out Stackable, with the one node hosting both the Kubernetes control plane and the Stackable services.

kind create cluster --name quickstart

Installing Kubernetes using K3s

K3s provides a quick way of installing Kubernetes. On your control node run the following command to install K3s:

curl -sfL https://get.k3s.io | sh -s - --write-kubeconfig-mode 644

So long as you have an Internet connection K3s will download and automatically configure a simple Kubernetes environment.

Create a symlink to the Kubernetes configuration from your home directory to allow tools like Helm to find the correct configuration.

mkdir ~/.kube
ln -s /etc/rancher/k3s/k3s.yaml ~/.kube/config

Testing your Kubernetes installation

To check if everything worked as expected you can use kubectl cluster-info to retrieve the cluster information. The output should look similar to:

Kubernetes control plane is running at https://127.0.0.1:6443
CoreDNS is running at https://127.0.0.1:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

If you set up your cluster using K3s you will additionally see the metrics server:

Kubernetes control plane is running at https://127.0.0.1:6443
CoreDNS is running at https://127.0.0.1:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
Metrics-server is running at https://127.0.0.1:6443/api/v1/namespaces/kube-system/services/https:metrics-server:https/proxy