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Deploy ClickHouse Operator and a ClickHouse Cluster on KubeSphere

ClickHouse is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP). RadonDB ClickHouse is a deeply customized ClickHouse cluster application maintaining ClickHouse cluster functions and featuring automated cluster management, data redistribution in clusters, and excellent performance with less cost.

This tutorial demonstrates how to deploy ClickHouse Operator and a ClickHouse Cluster on KubeSphere.

Prerequisites

You need to enable the OpenPitrix system.
You need to create a workspace, a project, and two user accounts (ws-admin and project-regular) for this tutorial. The account ws-admin must be granted the role of workspace-admin in the workspace, and the account project-regular must be invited to the project with the role of operator. This tutorial uses demo-workspace and demo-project for demonstration. If they are not ready, refer to Create Workspaces, Projects, Users and Roles.
You need to enable the gateway in your project to provide external access. If they are not ready, refer to Project Gateway.

Hands-on Lab

Step 1: Deploy ClickHouse Operator

Log in to the KubeSphere Web console as admin, and use Kubectl from the Toolbox in the lower-right corner to run the following command to install ClickHouse Operator. It is recommended that you have at least two worker nodes available in your cluster.
```
$ kubectl apply -f https://raw.githubusercontent.com/radondb/radondb-clickhouse-kubernetes/master/clickhouse-operator-install.yml
```
Note

This command will install ClickHouse Operator in the namespace kube-system. Therefore, ClickHouse Operator only needs to be installed once in a Kubernetes cluster.

You can see the expected output as below if the installation is successful.

$ kubectl apply -f https://raw.githubusercontent.com/radondb/radondb-clickhouse-kubernetes/main/clickhouse-operator-install.yml
customresourcedefinition.apiextensions.k8s.io/clickhouseinstallations.clickhouse.radondb.com created
customresourcedefinition.apiextensions.k8s.io/clickhouseinstallationtemplates.clickhouse.radondb.com created
customresourcedefinition.apiextensions.k8s.io/clickhouseoperatorconfigurations.clickhouse.radondb.com created
serviceaccount/clickhouse-operator created
clusterrole.rbac.authorization.k8s.io/clickhouse-operator-kube-system created
clusterrolebinding.rbac.authorization.k8s.io/clickhouse-operator-kube-system created
configmap/etc-clickhouse-operator-files created
configmap/etc-clickhouse-operator-confd-files created
configmap/etc-clickhouse-operator-configd-files created
configmap/etc-clickhouse-operator-templatesd-files created
configmap/etc-clickhouse-operator-usersd-files created
deployment.apps/clickhouse-operator created
service/clickhouse-operator-metrics created

You can run the following command to view the status of ClickHouse Operator resources.

$ kubectl get all --selector=app=clickhouse-operator -n kube-system

Expected output:

NAME                                      READY   STATUS    RESTARTS   AGE
pod/clickhouse-operator-6b8494c8f-tmkmn   2/2     Running   0          6m34s

NAME                                  TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
service/clickhouse-operator-metrics   ClusterIP   10.233.51.66   <none>        8888/TCP   6m34s

NAME                                  READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/clickhouse-operator   1/1     1            1           6m34s

NAME                                            DESIRED   CURRENT   READY   AGE
replicaset.apps/clickhouse-operator-6b8494c8f   1         1         1       6m34s

Step 2: Add an app repository

Log out of KubeSphere and log back in as ws-admin. In demo-workspace, go to App Repositories under App Management, and then click Add.
In the dialog that appears, enter clickhouse for the app repository name and https://radondb.github.io/radondb-clickhouse-kubernetes/ for the repository URL. Click Validate to verify the URL, and you will see a green check mark next to the URL if it is available. Click OK to continue.
Your repository will display in the list after it is successfully imported to KubeSphere.

Step 3: Deploy a ClickHouse Cluster

Log out of KubeSphere and log back in as project-regular. In demo-project, go to Apps under Application Workloads and click Create.
In the dialog that appears, select From App Template.
On the new page that appears, select clickhouse from the drop-down list and then click clickhouse-cluster.
On the Chart Files tab, you can view the configuration and download the values.yaml file. Click Install to continue.
On the Basic Information page, confirm the app name, app version, and deployment location. Click Next to continue.
On the App Settings tab, you can change the YAML file to customize settings. In this tutorial, click Install to use the default settings.
After a while, you can see the app is in the Running status.

Step 4: View ClickHouse cluster status

In Workloads under Application Workloads, click the StatefulSets tab, and you can see the StatefulSets are up and running.
Click a single StatefulSet to go to its detail page. You can see the metrics in line charts over a period of time under the Monitoring tab.
In Pods under Application Workloads, you can see all the Pods are up and running.
In Volumes under Storage, you can see the ClickHouse Cluster components are using persistent volumes.
Volume usage is also monitored. Click a volume item to go to its detail page.
On the Overview page of the project, you can see a list of resource usage in the current project.

Step 5: Access the ClickHouse cluster

Log out of KubeSphere and log back in as admin. Hover your cursor over the hammer icon in the lower-right corner, and then select Kubectl.
In the window that appears, run the following command and then navigate to the username and password of the ClickHouse cluster.
```
$ kubectl edit chi clickho-749j8s -n demo-project
```
Note

In the above command, clickho-749j8s is the ClickHouse application name and demo-project is the project name. Make sure you use your own application name and project name.
Run the following command to access the ClickHouse cluster, and then you can use command like show databases to interact with it.
```
$ kubectl exec -it chi-clickho-749j8s-all-nodes-0-0-0 -n demo-project -- clickhouse-client --user=clickhouse --password=c1ickh0use0perator
```
Note

In the above command, chi-clickho-749j8s-all-nodes-0-0-0 is the Pod name and you can find it in Pods under Application Workloads. Make sure you use your own Pod name, project name, username, and password.

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