Single-cluster install with kustomize

Quickstart with Kustomize to install K8ssandraCluster in single-cluster Kubernetes.

This topic shows how you can use Kustomize to declaratively install and configure the K8ssandraCluster custom resource in single-cluster local Kubernetes.

Prerequisites

If you haven’t already, see the install prerequisites.

Introduction

You can install K8ssandra Operator with Kustomize, which takes a declarative approach to configuring and deploying resources, whereas Helm takes more of an imperative approach.

Kustomize is integrated directly into kubectl. For example, kubectl apply -k essentially runs kustomize build over the specified directory followed by kubectl apply. See this topic for details on the integration of Kustomize into kubectl.

K8ssandra Operator uses some features of Kustomize that are only available in kubectl v1.23 or later. For this reason the following examples use kustomize build <dir> | kubectl apply -f -.

Single-cluster local Kubernetes

Let’s look at a single-cluster install to demonstrate that while K8ssandra Operator is designed for multi-cluster use, it can be used in a single cluster without any extra configuration.

Create kind cluster

Run setup-kind-multicluster.sh as follows:

./setup-kind-multicluster.sh --kind-worker-nodes 4

Install Cert Manager

We need to first install Cert Manager because it is a dependency of cass-operator:

kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.7.1/cert-manager.yaml

Install K8ssandra Operator

Install with:

kustomize build "github.com/k8ssandra/k8ssandra-operator/config/deployments/control-plane?ref=v1.1.1" | k apply --server-side -f -

Verify that the following CRDs are installed:

* `cassandrabackups.medusa.k8ssandra.io`
* `cassandrarestores.medusa.k8ssandra.io`
* `certificaterequests.cert-manager.io`
* `certificates.cert-manager.io`
* `challenges.acme.cert-manager.io`
* `clientconfigs.config.k8ssandra.io`
* `clusterissuers.cert-manager.io`
* `issuers.cert-manager.io`
* `k8ssandraclusters.k8ssandra.io`
* `orders.acme.cert-manager.io`
* `reapers.reaper.k8ssandra.io`
* `replicatedsecrets.replication.k8ssandra.io`
* `stargates.stargate.k8ssandra.io`


Check that there are two Deployments. The output should look similar to this:

```console
kubectl -n k8ssandra-operator get deployment
NAME                 READY   UP-TO-DATE   AVAILABLE   AGE
cass-operator-controller-manager   1/1     1            1           77s
k8ssandra-operator                 1/1     1            1           77s

Verify that the K8SSANDRA_CONTROL_PLANE environment variable is set to true:

kubectl -n k8ssandra-operator get deployment k8ssandra-operator -o jsonpath='{.spec.template.spec.containers[0].env[?(@.name=="K8SSANDRA_CONTROL_PLANE")].value}'

Deploy a K8ssandraCluster

Now we will deploy a K8ssandraCluster that consists of a 3-node Cassandra cluster and a Stargate node.

cat <<EOF | kubectl -n k8ssandra-operator apply -f -
apiVersion: k8ssandra.io/v1alpha1
kind: K8ssandraCluster
metadata:
  name: demo
spec:
  cassandra:
    serverVersion: "4.0.3"
    datacenters:
      - metadata:
          name: dc1
        size: 3
        storageConfig:
          cassandraDataVolumeClaimSpec:
            storageClassName: standard
            accessModes:
              - ReadWriteOnce
            resources:
              requests:
                storage: 5Gi
        config:
          jvmOptions:
            heapSize: 512M
        stargate:
          size: 1
          heapSize: 256M
EOF

Confirm that the resource has been created:

kubectl -n k8ssandra-operator get k8ssandraclusters
NAME   AGE
demo   45s
kubectl -n k8ssandra-operator describe k8ssandracluster demo
Name:         demo
Namespace:    k8ssandra-operator
Labels:       <none>
Annotations:  <none>
API Version:  k8ssandra.io/v1alpha1
Kind:         K8ssandraCluster
...
Status:
  Datacenters:
    dc1:
      Cassandra:
        Cassandra Operator Progress:  Updating
        Node Statuses:
Events:  <none>

Monitor the status of the deployment, eventually resulting in all the resources being in the Ready state:

kubectl -n k8ssandra-operator describe K8ssandraCluster demo
Name:         demo
Namespace:    k8ssandra-operator
Labels:       <none>
Annotations:  <none>
API Version:  k8ssandra.io/v1alpha1
Kind:         K8ssandraCluster
...
Status:
  Datacenters:
    dc1:
      Cassandra:
        Cassandra Operator Progress:  Ready
      ...
      Stargate:
        Available Replicas:  1
        Conditions:
          Last Transition Time:  2021-09-28T03:32:07Z
          Status:                True
          Type:                  Ready
        Deployment Refs:
          demo-dc1-default-stargate-deployment
        Progress:              Running
        Ready Replicas:        1
        Ready Replicas Ratio:  1/1
        Replicas:              1
        Service Ref:           demo-dc1-stargate-service
        Updated Replicas:      1
Events:                        <none>

Next steps

  • See other local install options, including K8ssandra Operator in multi-cluster Kubernetes.
  • Also, dig into the K8ssandra Operator components.


Last modified October 21, 2022: Upgrade CRD reference (00955bc)