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Reconfigure ClickHouse Cluster

This guide will show you how to use KubeDB Ops-manager operator to reconfigure a ClickHouse cluster.

Before You Begin

  • At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster.

  • Install KubeDB Provisioner and Ops-manager operator in your cluster following the steps here.

  • You should be familiar with the following KubeDB concepts:

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored in docs/examples/clickhouse directory of kubedb/docs repository.

Now, we are going to deploy a ClickHouse cluster using a supported version by KubeDB operator. Then we are going to apply ClickHouseOpsRequest to reconfigure its configuration.

Prepare ClickHouse Cluster

Now, we are going to deploy a ClickHouse topology cluster with version 24.4.1.

Deploy ClickHouse

At first, we will create a secret with the ch-config.yaml file containing required configuration settings.

ch-config.yaml:

profiles:
      default:
        max_query_size: 200000

Here, max_query_size is set to 200000, whereas the default value is 262144

Let’s create a k8s secret containing the above configuration where the file name will be the key and the file-content as the value:

apiVersion: v1
kind: Secret
metadata:
  name: ch-custom-config
  namespace: demo
type: Opaque
stringData:
  ch-config.yaml: |
    profiles:
      default:
        max_query_size: 200000    

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.10.17/docs/examples/clickhouse/reconfigure/ch-config-secret.yaml
secret/ch-custom-config created

In this section, we are going to create a ClickHouse object specifying spec.configSecret field to apply this custom configuration. Below is the YAML of the ClickHouse CR that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: ClickHouse
metadata:
  name: clickhouse-prod
  namespace: demo
spec:
  version: 24.4.1
  configSecret:
    name: ch-custom-config
  clusterTopology:
    clickHouseKeeper:
      externallyManaged: false
      spec:
        replicas: 3
        storage:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 1Gi
    cluster:
        name: appscode-cluster
        shards: 2
        replicas: 2
        podTemplate:
          spec:
            containers:
              - name: clickhouse
                resources:
                  limits:
                    memory: 4Gi
                  requests:
                    cpu: 500m
                    memory: 2Gi
            initContainers:
              - name: clickhouse-init
                resources:
                  limits:
                    memory: 1Gi
                  requests:
                    cpu: 500m
                    memory: 1Gi
        storage:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 1Gi
  deletionPolicy: WipeOut

Let’s create the ClickHouse CR we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2025.10.17/docs/examples/clickhouse/reconfigure/clickhouse-cluster.yaml
clickhouse.kubedb.com/clickhouse-prod created

Now, wait until clickhouse-prod has status Ready. i.e,

➤ kubectl get ch -n demo clickhouse-prod -w
NAME              TYPE                  VERSION   STATUS         AGE
clickhouse-prod   kubedb.com/v1alpha2   24.4.1    Provisioning   101s
clickhouse-prod   kubedb.com/v1alpha2   24.4.1    Provisioning   109s
.
.
clickhouse-prod   kubedb.com/v1alpha2   24.4.1    Ready          2m17s

Now, we will check if the clickhouse has started with the custom configuration we have provided.

Exec into the ClickHouse pod and execute the following commands to see the configurations:

➤ kubectl exec -it -n demo clickhouse-prod-appscode-cluster-shard-0-0 -- bash
Defaulted container "clickhouse" out of: clickhouse, clickhouse-init (init)
clickhouse@clickhouse-prod-appscode-cluster-shard-0-0:/$ cat /etc/clickhouse-server/conf.d/ch-config.yaml
profiles:
  default:
    max_query_size: 200000

Here, we can see that our given configuration is applied to the ClickHouse cluster . profiles.default.max_query_size is set to 200000 from the default value 262144.

Reconfigure using new config secret

Now we will reconfigure this cluster to set max_query_size to 150000.

Now, update our ch-config.yaml file with the new configuration.

profiles:
      default:
        max_query_size: 150000

Then, we will create a new secret with this configuration file.

At first, create clickhouse.yaml file containing required configuration settings.

$ cat clickhouse.yaml
read_request_timeout: 6500ms

Then, we will create a new secret with this configuration file.

apiVersion: v1
kind: Secret
metadata:
  name: new-ch-custom-config
  namespace: demo
type: Opaque
stringData:
  ch-config.yaml: |
    profiles:
      default:
        max_query_size: 150000    

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.10.17/docs/examples/clickhouse/reconfigure/new-ch-config-secret.yaml
secret/new-ch-custom-config created

Create ClickHouseOpsRequest

Now, we will use this secret to replace the previous secret using a ClickHouseOpsRequest CR. The ClickHouseOpsRequest yaml is given below,

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-cluster-reconfigure-with-secret
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: clickhouse-prod
  configuration:
    configSecret:
      name: new-ch-custom-config
  timeout: 10m
  apply: IfReady

Here,

  • spec.databaseRef.name specifies that we are reconfiguring clickhouse-prod database.
  • spec.type specifies that we are performing Reconfigure on our database.
  • spec.configSecret.name specifies the name of the new secret.

Let’s create the ClickHouseOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.10.17/docs/examples/clickhouse/reconfigure/ch-reconfigure-ops-with-secret.yaml
clickhouseopsrequest.ops.kubedb.com/chops-cluster-reconfigure-with-secret created

Verify the new configuration is working

If everything goes well, KubeDB Ops-manager operator will update the configSecret of ClickHouse object.

Let’s wait for ClickHouseOpsRequest to be Successful. Run the following command to watch ClickHouseOpsRequest CR,

➤ kubectl get clickhouseopsrequests -n demo 
NAME                                    TYPE          STATUS       AGE
chops-cluster-reconfigure-with-secret   Reconfigure   Successful   48m

We can see from the above output that the ClickHouseOpsRequest has succeeded. If we describe the ClickHouseOpsRequest we will get an overview of the steps that were followed to reconfigure the database.

➤ kubectl describe chops -n demo chops-cluster-reconfigure-with-secret 
Name:         chops-cluster-reconfigure-with-secret
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         ClickHouseOpsRequest
Metadata:
  Creation Timestamp:  2025-08-22T10:39:47Z
  Generation:          1
  Resource Version:    458839
  UID:                 54b3c1b1-976b-4129-9b08-dcb11426b990
Spec:
  Apply:  IfReady
  Configuration:
    Config Secret:
      Name:  new-ch-custom-config
  Database Ref:
    Name:   clickhouse-prod
  Timeout:  10m
  Type:     Reconfigure
Status:
  Conditions:
    Last Transition Time:  2025-08-22T10:39:47Z
    Message:               ClickHouse ops-request has started to reconfigure ClickHouse nodes
    Observed Generation:   1
    Reason:                Reconfigure
    Status:                True
    Type:                  Reconfigure
    Last Transition Time:  2025-08-22T10:39:55Z
    Message:               successfully reconciled the ClickHouse with new configure
    Observed Generation:   1
    Reason:                UpdatePetSets
    Status:                True
    Type:                  UpdatePetSets
    Last Transition Time:  2025-08-22T10:39:55Z
    Message:               reconcile; ConditionStatus:True
    Observed Generation:   1
    Status:                True
    Type:                  Reconcile
    Last Transition Time:  2025-08-22T10:42:20Z
    Message:               Successfully restarted all nodes
    Observed Generation:   1
    Reason:                RestartNodes
    Status:                True
    Type:                  RestartNodes
    Last Transition Time:  2025-08-22T10:40:00Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-0-0
    Last Transition Time:  2025-08-22T10:40:00Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-0-0
    Last Transition Time:  2025-08-22T10:40:05Z
    Message:               running pod; ConditionStatus:False
    Observed Generation:   1
    Status:                False
    Type:                  RunningPod
    Last Transition Time:  2025-08-22T10:40:40Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-0-1
    Last Transition Time:  2025-08-22T10:40:40Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-0-1
    Last Transition Time:  2025-08-22T10:41:20Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-1-0
    Last Transition Time:  2025-08-22T10:41:20Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-1-0
    Last Transition Time:  2025-08-22T10:42:00Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-1-1
    Last Transition Time:  2025-08-22T10:42:00Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-1-1
    Last Transition Time:  2025-08-22T10:42:20Z
    Message:               Successfully completed reconfigure ClickHouse
    Observed Generation:   1
    Reason:                Successful
    Status:                True
    Type:                  Successful
  Observed Generation:     1
  Phase:                   Successful
Events:
  Type     Reason                                                                               Age   From                         Message
  ----     ------                                                                               ----  ----                         -------
  Normal   Starting                                                                             49m   KubeDB Ops-manager Operator  Start processing for ClickHouseOpsRequest: demo/chops-cluster-reconfigure-with-secret
  Normal   Starting                                                                             49m   KubeDB Ops-manager Operator  Pausing ClickHouse databse: demo/clickhouse-prod
  Normal   Successful                                                                           49m   KubeDB Ops-manager Operator  Successfully paused ClickHouse database: demo/clickhouse-prod for ClickHouseOpsRequest: chops-cluster-reconfigure-with-secret
  Warning  reconcile; ConditionStatus:True                                                      49m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Warning  reconcile; ConditionStatus:True                                                      49m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Warning  reconcile; ConditionStatus:True                                                      49m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Normal   UpdatePetSets                                                                        49m   KubeDB Ops-manager Operator  successfully reconciled the ClickHouse with new configure
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0    48m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0  48m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
  Warning  running pod; ConditionStatus:False                                                   48m   KubeDB Ops-manager Operator  running pod; ConditionStatus:False
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1    48m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1  48m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0    47m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0  47m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1    46m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1  46m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
  Normal   RestartNodes                                                                         46m   KubeDB Ops-manager Operator  Successfully restarted all nodes
  Normal   Starting                                                                             46m   KubeDB Ops-manager Operator  Resuming ClickHouse database: demo/clickhouse-prod
  Normal   Successful                                                                           46m   KubeDB Ops-manager Operator  Successfully resumed ClickHouse database: demo/clickhouse-prod for ClickHouseOpsRequest: chops-cluster-reconfigure-with-secret

Now let’s exec one of the instance to check the new configuration we have provided.

➤ kubectl exec -it -n demo clickhouse-prod-appscode-cluster-shard-0-0 -- bash
Defaulted container "clickhouse" out of: clickhouse, clickhouse-init (init)
clickhouse@clickhouse-prod-appscode-cluster-shard-0-0:/$ cat /etc/clickhouse-server/conf.d/ch-config.yaml 
profiles:
  default:
    max_query_size: "150000"

As we can see from the configuration of ready clickhouse, the value of max_query_size has been changed from 200000 to 150000. So the reconfiguration of the cluster is successful.

Reconfigure using apply config

Now we will reconfigure this cluster again to set 180000 to ``. This time we won’t use a new secret. We will use the applyConfig field of the ClickHouseOpsRequest. This will merge the new config in the existing secret.

Create ClickHouseOpsRequest

Now, we will use the new configuration in the applyConfig field in the ClickHouseOpsRequest CR. The ClickHouseOpsRequest yaml is given below,

apiVersion: ops.kubedb.com/v1alpha1
kind: ClickHouseOpsRequest
metadata:
  name: chops-cluster-reconfigure-with-config
  namespace: demo
spec:
  type: Reconfigure
  databaseRef:
    name: clickhouse-prod
  configuration:
    applyConfig:
      ch-config.yaml: |
        profiles:
          default:
            max_query_size: 180000        
  timeout: 10m
  apply: IfReady

Here,

  • spec.databaseRef.name specifies that we are reconfiguring clickhouse-prod cluster.
  • spec.type specifies that we are performing Reconfigure on clickhouse.
  • spec.configuration.applyConfig specifies the new configuration that will be merged in the existing secret.

Let’s create the ClickHouseOpsRequest CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2025.10.17/docs/examples/clickhouse/reconfigure/ch-reconfigure-ops-with-apply-config.yaml
clickhouseopsrequest.ops.kubedb.com/chops-cluster-reconfiugre-with-config created

Verify the new configuration is working

If everything goes well, KubeDB Ops-manager operator will merge this new config with the existing configuration.

Let’s wait for ClickHouseOpsRequest to be Successful. Run the following command to watch ClickHouseOpsRequest CR,

➤ kubectl get chops -n demo chops-cluster-reconfiugre-with-config 
NAME                                    TYPE          STATUS       AGE
chops-cluster-reconfiugre-with-config   Reconfigure   Successful   12m

We can see from the above output that the ClickHouseOpsRequest has succeeded. If we describe the ClickHouseOpsRequest we will get an overview of the steps that were followed to reconfigure the cluster.

➤ kubectl describe chops -n demo chops-cluster-reconfiugre-with-config 
Name:         chops-cluster-reconfiugre-with-config
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         ClickHouseOpsRequest
Metadata:
  Creation Timestamp:  2025-08-22T11:34:23Z
  Generation:          1
  Resource Version:    466167
  UID:                 2270c10b-490c-43db-9cc9-92171b9513bb
Spec:
  Apply:  IfReady
  Configuration:
    Apply Config:
      config.yaml:  profiles:
  default:
    max_query_size: 180000

  Database Ref:
    Name:   clickhouse-prod
  Timeout:  10m
  Type:     Reconfigure
Status:
  Conditions:
    Last Transition Time:  2025-08-22T11:34:23Z
    Message:               ClickHouse ops-request has started to reconfigure ClickHouse nodes
    Observed Generation:   1
    Reason:                Reconfigure
    Status:                True
    Type:                  Reconfigure
    Last Transition Time:  2025-08-22T11:34:26Z
    Message:               Successfully prepared user provided custom config secret
    Observed Generation:   1
    Reason:                PrepareCustomConfig
    Status:                True
    Type:                  PrepareCustomConfig
    Last Transition Time:  2025-08-22T11:34:31Z
    Message:               successfully reconciled the ClickHouse with new configure
    Observed Generation:   1
    Reason:                UpdatePetSets
    Status:                True
    Type:                  UpdatePetSets
    Last Transition Time:  2025-08-22T11:34:31Z
    Message:               reconcile; ConditionStatus:True
    Observed Generation:   1
    Status:                True
    Type:                  Reconcile
    Last Transition Time:  2025-08-22T11:36:56Z
    Message:               Successfully restarted all nodes
    Observed Generation:   1
    Reason:                RestartNodes
    Status:                True
    Type:                  RestartNodes
    Last Transition Time:  2025-08-22T11:34:36Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-0-0
    Last Transition Time:  2025-08-22T11:34:36Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-0-0
    Last Transition Time:  2025-08-22T11:34:41Z
    Message:               running pod; ConditionStatus:False
    Observed Generation:   1
    Status:                False
    Type:                  RunningPod
    Last Transition Time:  2025-08-22T11:34:56Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-0-1
    Last Transition Time:  2025-08-22T11:34:56Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-0-1
    Last Transition Time:  2025-08-22T11:35:36Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-1-0
    Last Transition Time:  2025-08-22T11:35:36Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-1-0
    Last Transition Time:  2025-08-22T11:36:21Z
    Message:               get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--clickhouse-prod-appscode-cluster-shard-1-1
    Last Transition Time:  2025-08-22T11:36:21Z
    Message:               evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--clickhouse-prod-appscode-cluster-shard-1-1
    Last Transition Time:  2025-08-22T11:36:56Z
    Message:               Successfully completed reconfigure ClickHouse
    Observed Generation:   1
    Reason:                Successful
    Status:                True
    Type:                  Successful
  Observed Generation:     1
  Phase:                   Successful
Events:
  Type     Reason                                                                               Age   From                         Message
  ----     ------                                                                               ----  ----                         -------
  Normal   Starting                                                                             13m   KubeDB Ops-manager Operator  Start processing for ClickHouseOpsRequest: demo/chops-cluster-reconfiugre-with-config
  Normal   Starting                                                                             13m   KubeDB Ops-manager Operator  Pausing ClickHouse databse: demo/clickhouse-prod
  Normal   Successful                                                                           13m   KubeDB Ops-manager Operator  Successfully paused ClickHouse database: demo/clickhouse-prod for ClickHouseOpsRequest: chops-cluster-reconfiugre-with-config
  Warning  reconcile; ConditionStatus:True                                                      13m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Warning  reconcile; ConditionStatus:True                                                      13m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Warning  reconcile; ConditionStatus:True                                                      13m   KubeDB Ops-manager Operator  reconcile; ConditionStatus:True
  Normal   UpdatePetSets                                                                        13m   KubeDB Ops-manager Operator  successfully reconciled the ClickHouse with new configure
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0    13m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0  13m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-0
  Warning  running pod; ConditionStatus:False                                                   13m   KubeDB Ops-manager Operator  running pod; ConditionStatus:False
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1    12m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1  12m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-0-1
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0    12m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0  12m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-0
  Warning  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1    11m   KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
  Warning  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1  11m   KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:clickhouse-prod-appscode-cluster-shard-1-1
  Normal   RestartNodes                                                                         10m   KubeDB Ops-manager Operator  Successfully restarted all nodes
  Normal   Starting                                                                             10m   KubeDB Ops-manager Operator  Resuming ClickHouse database: demo/clickhouse-prod
  Normal   Successful                                                                           10m   KubeDB Ops-manager Operator  Successfully resumed ClickHouse database: demo/clickhouse-prod for ClickHouseOpsRequest: chops-cluster-reconfiugre-with-config

Now let’s exec into one of the instance to check the new configuration we have provided.

➤ kubectl exec -it -n demo clickhouse-prod-appscode-cluster-shard-0-0 -- bash
Defaulted container "clickhouse" out of: clickhouse, clickhouse-init (init)
clickhouse@clickhouse-prod-appscode-cluster-shard-0-0:/$ cat /etc/clickhouse-server/conf.d/ch-config.yaml 
profiles:
    default:
        max_query_size: 180000

As we can see from the configuration of ready clickhouse, the value of max_query_size has been changed from 150000 to 180000. So the reconfiguration of the database using the applyConfig field is successful.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

kubectl delete ch -n demo clickhouse-prod
kubectl delete clickhouseopsrequest -n demo chops-cluster-reconfigure-with-config chops-cluster-reconfigure-with-secret
kubectl delete secret -n demo ch-custom-config new-ch-custom-config
kubectl delete ns demo

Next Steps

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