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ClickHouseOpsRequest

What is ClickHouseOpsRequest

ClickHouseOpsRequest is a Kubernetes Custom Resource Definitions (CRD). It provides a declarative configuration for ClickHouse administrative operations like database version updating, horizontal scaling, vertical scaling etc. in a Kubernetes native way.

ClickHouseOpsRequest CRD Specifications

Like any official Kubernetes resource, a ClickHouseOpsRequest has TypeMeta, ObjectMeta, Spec and Status sections.

Here, some sample ClickHouseOpsRequest CRs for different administrative operations is given below:

Sample ClickHouseOpsRequest for updating database:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: update-version
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: clickhouse-prod
  type: UpdateVersion
  updateVersion:
    targetVersion: 25.7.1
status:
  conditions:
    - lastTransitionTime: "2025-08-21T07:54:21Z"
      message: Successfully completed update clickhouse version
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest for Horizontal Scaling of Database Cluster:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-scale-horizontal-up
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: clickhouse-prod
  horizontalScaling:
    replicas: 3
  type: HorizontalScaling
status:
  conditions:
    - lastTransitionTime: "2025-08-21T08:04:41Z"
      message: Successfully completed horizontally scale ClickHouse cluster
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest for Vertical Scaling of Database:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: ch-scale-vertical-cluster
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: clickhouse-prod
  type: VerticalScaling
  verticalScaling:
    node:
      resources:
        limits:
          cpu: "2"
          memory: 2Gi
        requests:
          cpu: "2"
          memory: 2Gi
status:
  conditions:
    - lastTransitionTime: "2025-08-21T08:15:43Z"
      message: Successfully completed the vertical scaling for ClickHouse
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest Objects for Reconfiguring ClickHouse database with config:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-reconfiugre
  namespace: demo
spec:
  apply: IfReady
  configuration:
    applyConfig:
      config.yaml: |
        profiles:
          default:
            max_query_size: 180000        
  databaseRef:
    name: clickhouse-prod
  type: Reconfigure
status:
  conditions:
    - lastTransitionTime: "2025-08-21T08:27:41Z"
      message: Successfully completed reconfigure ClickHouse
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest Objects for Reconfiguring ClickHouse database with secret:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-reconfiugre
  namespace: demo
spec:
  apply: IfReady
  configuration:
    configSecret:
      name: ch-custom-config
  databaseRef:
    name: clickhouse-prod
  type: Reconfigure
status:
  conditions:
    - lastTransitionTime: "2025-08-21T10:00:04Z"
      message: Successfully completed reconfigure ClickHouse
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest Objects for Volume Expansion of ClickHouse:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: ch-offline-volume-expansion
  namespace: demo
spec:
  apply: IfReady
  databaseRef:
    name: clickhouse-prod
  type: VolumeExpansion
  volumeExpansion:
    mode: Offline
    node: 2Gi
status:
  conditions:
    - lastTransitionTime: "2025-08-21T10:36:53Z"
      message: Successfully completed volumeExpansion for ClickHouse
      observedGeneration: 1
      reason: Successful
      status: "True"
      type: Successful
  observedGeneration: 1
  phase: Successful

Sample ClickHouseOpsRequest Objects for Reconfiguring TLS of the database:

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-add-tls
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: clickhouse-prod
  tls:
    sslVerificationMode: "strict"
    issuerRef:
      apiGroup: cert-manager.io
      kind: Issuer
      name: ch-issuer
    certificates:
      - alias: server
        subject:
          organizations:
            - kubedb:server
        dnsNames:
          - localhost
        ipAddresses:
          - "127.0.0.1"

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-rotate
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: clickhouse-prod
  tls:
    rotateCertificates: true

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-update-issuer
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: clickhouse-prod
  tls:
    issuerRef:
      name: ch-new-issuer
      kind: Issuer
      apiGroup: "cert-manager.io"

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-remove-tls
  namespace: demo
spec:
  type: ReconfigureTLS
  databaseRef:
    name: clickhouse-prod
  tls:
    remove: true

Here, we are going to describe the various sections of a ClickHouseOpsRequest crd.

A ClickHouseOpsRequest object has the following fields in the spec section.

spec.databaseRef

spec.databaseRef is a required field that point to the ClickHouse object for which the administrative operations will be performed. This field consists of the following sub-field:

• spec.databaseRef.name : specifies the name of the ClickHouse object.

spec.type

spec.type specifies the kind of operation that will be applied to the database. Currently, the following types of operations are allowed in ClickHouseOpsRequest.

• UpdateVersion
• HorizontalScaling
• VerticalScaling
• VolumeExpansion
• Reconfigure
• ReconfigureTLS
• Restart

You can perform only one type of operation on a single ClickHouseOpsRequest CR. For example, if you want to update your database and scale up its replica then you have to create two separate ClickHouseOpsRequest. At first, you have to create a ClickHouseOpsRequest for updating. Once it is completed, then you can create another ClickHouseOpsRequest for scaling.

spec.updateVersion

If you want to update you ClickHouse version, you have to specify the spec.updateVersion section that specifies the desired version information. This field consists of the following sub-field:

• spec.updateVersion.targetVersion refers to a ClickHouseVersion CR that contains the ClickHouse version information where you want to update.

You can only update between ClickHouse versions. KubeDB does not support downgrade for ClickHouse.

spec.horizontalScaling.node

If you want to scale-up or scale-down your ClickHouse cluster or different components of it, you have to specify spec.horizontalScaling.node section.

spec.verticalScaling.node

spec.verticalScaling.node is a required field specifying the information of ClickHouse resources like cpu, memory etc that will be scaled. this has the below structure:

requests:
  memory: "200Mi"
  cpu: "0.1"
limits:
  memory: "300Mi"
  cpu: "0.2"

Here, when you specify the resource request, the scheduler uses this information to decide which node to place the container of the Pod on and when you specify a resource limit for the container, the kubelet enforces those limits so that the running container is not allowed to use more of that resource than the limit you set. You can found more details from here.

spec.volumeExpansion

To use the volume expansion feature the storage class must support volume expansion

If you want to expand the volume of your ClickHouse cluster or different components of it, you have to specify spec.volumeExpansion section. This field consists of the following sub-field:

• spec.mode specifies the volume expansion mode. Supported values are Online & Offline. The default is Online.
• spec.volumeExpansion.node indicates the desired size for the persistent volume for a ClickHouse cluster.

Example usage of this field is given below:

spec:
  volumeExpansion:
    node: "2Gi"

This will expand the volume size of all the combined nodes to 2 GB.

spec.configuration

If you want to reconfigure your Running ClickHouse cluster or different components of it with new custom configuration, you have to specify spec.configuration section. This field consists of the following sub-field:

• spec.configuration.configSecret points to a secret in the same namespace of a ClickHouse resource, which contains the new custom configurations. If there are any configSecret set before in the database, this secret will replace it.

• applyConfig is a map where the key represents the target config file (e.g., config.yaml) and the value contains the corresponding configuration content.

  applyConfig:
    config.yaml: |
      profiles:
        default:
          max_query_size: 180000      

• removeCustomConfig is a boolean field. Specify this field to true if you want to remove all the custom configuration from the deployed clickhouse cluster.

spec.tls

If you want to reconfigure the TLS configuration of your ClickHouse i.e. add TLS, remove TLS, update issuer/cluster issuer or Certificates and rotate the certificates, you have to specify spec.tls section. This field consists of the following sub-field:

• spec.tls.issuerRef specifies the issuer name, kind and api group.
• spec.tls.certificates specifies the certificates. You can learn more about this field from here.
• spec.tls.rotateCertificates specifies that we want to rotate the certificate of this clickhouse.
• spec.tls.remove specifies that we want to remove tls from this clickhouse.

spec.timeout

As we internally retry the ops request steps multiple times, This timeout field helps the users to specify the timeout for those steps of the ops request (in second). If a step doesn’t finish within the specified timeout, the ops request will result in failure.

spec.apply

This field controls the execution of obsRequest depending on the database state. It has two supported values: Always & IfReady. Use IfReady, if you want to process the opsRequest only when the database is Ready. And use Always, if you want to process the execution of opsReq irrespective of the Database state.

ClickHouseOpsRequest Status

.status describes the current state and progress of a ClickHouseOpsRequest operation. It has the following fields:

status.phase

status.phase indicates the overall phase of the operation for this ClickHouseOpsRequest. It can have the following three values:

Important: Ops-manager Operator can skip an opsRequest, only if its execution has not been started yet & there is a newer opsRequest applied in the cluster. spec.type has to be same as the skipped one, in this case.

status.observedGeneration

status.observedGeneration shows the most recent generation observed by the ClickHouseOpsRequest controller.

status.conditions

status.conditions is an array that specifies the conditions of different steps of ClickHouseOpsRequest processing. Each condition entry has the following fields:

• types specifies the type of the condition. ClickHouseOpsRequest has the following types of conditions:

• The status field is a string, with possible values True, False, and Unknown.
  • status will be True if the current transition succeeded.
  • status will be False if the current transition failed.
  • status will be Unknown if the current transition was denied.
• The message field is a human-readable message indicating details about the condition.
• The reason field is a unique, one-word, CamelCase reason for the condition’s last transition.
• The lastTransitionTime field provides a timestamp for when the operation last transitioned from one state to another.
• The observedGeneration shows the most recent condition transition generation observed by the controller.