Deploy ClickHouse on Kubernetes without Operator

 

Clickhouse is a fast SQL based database. To deploy it we can use the clickhouse operator. This however is an overkill for a small deployment such as a deployment for local testing and debug.

This post describes deployment of a single pod clickhouse without the need of an operator.

We start by creating a role and a service account.

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: my-clickhouse-role
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: my-clickhouse-service-account
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: my-clickhouse-role-binding
subjects:
  - kind: ServiceAccount
    name: my-clickhouse-service-account
    namespace: default
roleRef:
  kind: ClusterRole
  name: my-clickhouse-role
  apiGroup: rbac.authorization.k8s.io
    
    

Next we add the a config map that includes the required configuration files.

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-clickhouse-config
    
    
data:
  custom.xml: |-
    <clickhouse>
        <logger>
            <level>information</level>
            <console>true</console>
        </logger>
    </clickhouse>
  users.xml: |-
    <clickhouse>
        <users>
            <default>
                <password></password>
                <networks>
                    <ip>::/0</ip>
                </networks>
            </default>
        </users>
    </clickhouse>

To make the tables persistent we add a persistent volume to hostpath.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-clickhouse-pv-0
  labels:
    type: local
spec:
  storageClassName: hostpath-my-clickhouse
  capacity:
    storage: 100Mi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/hostpath/my-clickhouse"

We expose the clickhouse port as well as the HTTP based port in a service.

apiVersion: v1
kind: Service
metadata:
  name: my-clickhouse-service
spec:
  selector:
    configid: my-clickhouse-container
  type: ClusterIP
  ports:
    - name: native
      port: 9000
      targetPort: 9000
    - name: http
      port: 8123
      targetPort: 8123

And finally we add the statefulset to run the clickhouse.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: my-clickhouse-statefulset
spec:
  serviceName: my-clickhouse-service
  replicas: 1
  selector:
    matchLabels:
      configid: my-clickhouse-container
  template:
    metadata:
      labels:
        configid: my-clickhouse-container        
        
        
    spec:
      serviceAccountName: my-clickhouse-service-account
      containers:
        - name: my-clickhouse
          image: clickhouse/clickhouse-server:latest
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 9000
              name: native
            - containerPort: 8123
              name: http
          volumeMounts:
            - name: pvc
              mountPath: /var/lib/clickhouse
            - name: my-clickhouse-config
              mountPath: /etc/clickhouse-server/config.d/custom.xml
              subPath: custom.xml
            - name: my-clickhouse-config
              mountPath: /etc/clickhouse-server/users.d/users.xml
              subPath: users.xml
      volumes:
        - name: my-clickhouse-config
          configMap:
            name: my-clickhouse-config
  volumeClaimTemplates:
    - metadata:
        name: pvc
      spec:
        accessModes: [ "ReadWriteOnce" ]
        storageClassName: "hostpath-my-clickhouse"
        resources:
          requests:
            storage: 100Mi