Configure cluster parameters

This guide shows how to configure cluster parameters.

From v0.9.0, KubeBlocks supports dynamic configuration. When the specification of a database instance changes (e.g. a user vertically scales a cluster), KubeBlocks automatically matches the appropriate configuration template based on the new specification. This is because different specifications of a database instance may require different optimal configurations to optimize performance and resource utilization. When you choose a different database instance specification, KubeBlocks automatically detects it and determines the best database configuration for the new specification, ensuring optimal performance and configuration of the database under the new specifications.

This feature simplifies the process of configuring parameters, which saves you from manually configuring database parameters as KubeBlocks handles the updates and configurations automatically to adapt to the new specifications. This saves time and effort and reduces performance issues caused by incorrect configuration.

But it's also important to note that the dynamic parameter configuration doesn't apply to all parameters. Some parameters may require manual configuration. Additionally, if you have manually modified database parameters before, KubeBlocks may overwrite your customized configurations when updating the database configuration template. Therefore, when using the dynamic configuration feature, it is recommended to back up and record your custom configuration so that you can restore them if needed.

kbcli

View parameter information

View the current configuration file of a cluster.

kbcli cluster describe-config mycluster -n demo

From the meta information, the cluster mycluster has a configuration file named my.cnf.

You can also view the details of this configuration file and parameters.

• View the details of the current configuration file.

  kbcli cluster describe-config mycluster --show-detail -n demo

• View the parameter description.

  kbcli cluster explain-config mycluster -n demo | head -n 20

• View the user guide of a specified parameter.

  kbcli cluster explain-config mycluster --param=innodb_buffer_pool_size --config-specs=mysql-replication-config -n demo

  --config-specs is required to specify a configuration template since MySQL currently supports multiple templates. You can run kbcli cluster describe-config mycluster to view the all template names.

  Output

  component: mysql
  template meta:
    ConfigSpec: mysql-replication-config  ComponentName: mysql    ClusterName: mycluster
  
  Configure Constraint:
    Parameter Name:     innodb_buffer_pool_size
    Allowed Values:     [5242880-18446744073709552000]
    Scope:              Global
    Dynamic:            true
    Type:               integer
    Description:        The size in bytes of the memory buffer innodb uses to cache data and indexes of its tables 
  • Allowed Values: It defines the valid value range of this parameter.
  • Dynamic: The value of Dynamic in Configure Constraint defines how the parameter configuration takes effect. There are two different configuration strategies based on the effectiveness type of modified parameters, i.e. dynamic and static.
    • When Dynamic is true, it means the effectiveness type of parameters is dynamic and can be configured online.
    • When Dynamic is false, it means the effectiveness type of parameters is static and a pod restarting is required to make the configuration effective.
  • Description: It describes the parameter definition.

Configure parameters

Configure parameters with configure command

The example below takes configuring max_connections and innodb_buffer_pool_size as an example.

1. View the current values of max_connections and innodb_buffer_pool_size.

   kbcli cluster connect mycluster -n demo

   mysql> show variables like '%max_connections%';
   >
   +-----------------+-------+
   | Variable_name   | Value |
   +-----------------+-------+
   | max_connections | 167   |
   +-----------------+-------+
   1 row in set (0.04 sec)

   mysql> show variables like '%innodb_buffer_pool_size%';
   >
   +-------------------------+-----------+
   | Variable_name           | Value     |
   +-------------------------+-----------+
   | innodb_buffer_pool_size | 134217728 |
   +-------------------------+-----------+
   1 row in set (0.00 sec)

2. Adjust the values of max_connections and innodb_buffer_pool_size.

   kbcli cluster configure mycluster --set=max_connections=600,innodb_buffer_pool_size=512M -n demo
   note

   Make sure the value you set is within the Allowed Values of this parameter. If you set a value that does not meet the value range, the system prompts an error. For example,

   kbcli cluster configure mycluster  --set=max_connections=200,innodb_buffer_pool_size=2097152 -n demo
   error: failed to validate updated config: [failed to cue template render configure: [mysqld.innodb_buffer_pool_size: invalid value 2097152 (out of bound >=5242880):
    343:34
   ]
   ]

3. Search the status of the parameter configuration.

   Status.Progress shows the overall status of the parameter configuration and Conditions show the details.

   kbcli cluster describe-ops mycluster-reconfiguring-pxs46 -n demo
   Output

   Spec:
   Name: mycluster-reconfiguring-pxs46 NameSpace: demo Cluster: mycluster  Type: Reconfiguring
   
   Command:
     kbcli cluster configure mycluster --components=mysql --config-specs=mysql-replication-config --config-file=my.cnf --set innodb_buffer_pool_size=512M --set max_connections=600 --namespace=demo
   
   Status:
     Start Time:         Jul 05,2024 19:00 UTC+0800
     Completion Time:    Jul 05,2024 19:00 UTC+0800
     Duration:           2s
     Status:             Succeed
     Progress:           2/2
                         OBJECT-KEY   STATUS   DURATION   MESSAGE
   
   Conditions:
   LAST-TRANSITION-TIME         TYPE                 REASON                            STATUS   MESSAGE
   Jul 05,2024 19:00 UTC+0800   WaitForProgressing   WaitForProgressing                True     wait for the controller to process the OpsRequest: mycluster-reconfiguring-pxs46 in Cluster: mycluster
   Jul 05,2024 19:00 UTC+0800   Validated            ValidateOpsRequestPassed          True     OpsRequest: mycluster-reconfiguring-pxs46 is validated
   Jul 05,2024 19:00 UTC+0800   Reconfigure          ReconfigureStarted                True     Start to reconfigure in Cluster: mycluster, Component: mysql
   Jul 05,2024 19:00 UTC+0800   Succeed              OpsRequestProcessedSuccessfully   True     Successfully processed the OpsRequest: mycluster-reconfiguring-pxs46 in Cluster: mycluster
   
   Warning Events: <none>

4. Connect to the database to verify whether the parameters are configured as expected.

   It takes about 30 seconds for the configuration to take effect because the kubelet requires some time to sync changes in the ConfigMap to the Pod's volume.

   kbcli cluster connect mycluster -n demo

   mysql> show variables like '%max_connections%';
   >
   +-----------------+-------+
   | Variable_name   | Value |
   +-----------------+-------+
   | max_connections | 600   |
   +-----------------+-------+
   1 row in set (0.04 sec)

   mysql> show variables like '%innodb_buffer_pool_size%';
   >
   +-------------------------+-----------+
   | Variable_name           | Value     |
   +-------------------------+-----------+
   | innodb_buffer_pool_size | 536870912 |
   +-------------------------+-----------+
   1 row in set (0.00 sec)

Configure parameters with edit-config command

For your convenience, KubeBlocks offers a tool edit-config to help you configure parameters in a visualized way.

For Linux and macOS, you can edit configuration files by vi. For Windows, you can edit files on the notepad.

1. Edit the configuration file.

   kbcli cluster edit-config mycluster --config-spec=mysql-replication-config -n demo
   note

   • Since MySQL currently supports multiple templates, it is required to use --config-spec to specify a configuration template. You can run kbcli cluster describe-config mycluster to view all template names.
   • If there are multiple components in a cluster, use --components to specify a component.

2. View the status of the parameter configuration.

   kbcli cluster describe-ops mycluster-reconfiguring-bbh86 -n demo

3. Connect to the database to verify whether the parameters are configured as expected.

   kbcli cluster connect mycluster -n demo
   note

   1. For the edit-config function, static parameters and dynamic parameters cannot be edited at the same time.
   2. Deleting a parameter will be supported later.

View history and compare differences

After the configuration is completed, you can search the configuration history and compare the parameter differences.

View the parameter configuration history.

kbcli cluster describe-config mycluster -n demo
>
component: mysql

ConfigSpecs Meta:
CONFIG-SPEC-NAME           FILE                              ENABLED   TEMPLATE                          CONSTRAINT                           RENDERED                                   COMPONENT   CLUSTER
mysql-replication-config   my.cnf                            true      oracle-mysql8.0-config-template   oracle-mysql8.0-config-constraints   mycluster-mysql-mysql-replication-config   mysql       mycluster
agamotto-configuration     agamotto-config.yaml              false     mysql-agamotto-configuration                                           mycluster-mysql-agamotto-configuration     mysql       mycluster
agamotto-configuration     agamotto-config-with-proxy.yaml   false     mysql-agamotto-configuration                                           mycluster-mysql-agamotto-configuration     mysql       mycluster

History modifications:
OPS-NAME                        CLUSTER     COMPONENT   CONFIG-SPEC-NAME           FILE     STATUS    POLICY              PROGRESS   CREATED-TIME                 VALID-UPDATED
mycluster-reconfiguring-pxs46   mycluster   mysql       mysql-replication-config   my.cnf   Succeed   syncDynamicReload   2/2        Jul 05,2024 19:00 UTC+0800   {"my.cnf":"{\"mysqld\":{\"innodb_buffer_pool_size\":\"512M\",\"max_connections\":\"600\"}}"}
mycluster-reconfiguring-x52fb   mycluster   mysql       mysql-replication-config   my.cnf   Succeed   syncDynamicReload   2/2        Jul 05,2024 19:04 UTC+0800   {"my.cnf":"{\"mysqld\":{\"max_connections\":\"1000\"}}"}                    

From the above results, there are two parameter modifications.

Compare these modifications to view the configured parameters and their different values for different versions.

kbcli cluster diff-config mycluster-reconfiguring-pxs46 mycluster-reconfiguring-x9zsf -n demo
>
DIFF-CONFIGURE RESULT:
  ConfigFile: my.cnf    TemplateName: mysql-replication-config ComponentName: mysql    ClusterName: mycluster       UpdateType: update      

PARAMETERNAME             mycluster-reconfiguring-pxs46   mycluster-reconfiguring-x9zsf   
max_connections           600                             2000                                      
innodb_buffer_pool_size   512M                            1G 

Edit config file

KubeBlocks supports configuring cluster parameters by editing its configuration file.

1. Get the configuration file of this cluster.

   kubectl edit configurations.apps.kubeblocks.io mycluster-mysql -n demo

2. Configure parameters according to your needs. The example below adds the spec.configFileParams part to configure max_connections.

   spec:
     clusterRef: mycluster
     componentName: mysql
     configItemDetails:
     - configFileParams:
         my.cnf:
           parameters:
             max_connections: "600"
       configSpec:
         constraintRef: oracle-mysql8.0-config-constraints
         name: mysql-replication-config
         namespace: kb-system
         templateRef: oracle-mysql8.0-config-template
         volumeName: mysql-config
       name: mysql-replication-config
     - configSpec:
         defaultMode: 292

3. Connect to this cluster to verify whether the configuration takes effect.

   1. Get the username and password.

      kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.username}' | base64 -d
      >
      root
      
      kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.password}' | base64 -d
      >
      2gvztbvz

   2. Connect to this cluster and verify whether the parameters are configured as expected.

      kubectl exec -ti -n demo mycluster-mysql-0 -- bash
      
      mysql -uroot -p2gvztbvz
      >
      mysql> show variables like 'max_connections';
      +-----------------+-------+
      | Variable_name   | Value |
      +-----------------+-------+
      | max_connections | 600   |
      +-----------------+-------+
      1 row in set (0.00 sec)

note

Just in case you cannot find the configuration file of your cluster, you can switch to the kbcli tab to view the current configuration file of a cluster.

OpsRequest

KubeBlocks supports configuring cluster parameters with OpsRequest.

1. Define an OpsRequest file and configure the parameters in the OpsRequest in a yaml file named mycluster-configuring-demo.yaml. In this example, max_connections is configured as 600.

   apiVersion: apps.kubeblocks.io/v1alpha1
   kind: OpsRequest
   metadata:
     name: mycluster-configuring-demo
     namespace: demo
   spec:
     clusterName: mycluster
     reconfigure:
       componentName: mysql
       configurations:
       - keys:
         - key: my.cnf
           parameters:
           - key: max_connections
             value: "600"
         name: mysql-replication-configuration
     preConditionDeadlineSeconds: 0
     type: Reconfiguring
   EOF

   Field	Definition
   metadata.name	It specifies the name of this OpsRequest.
   metadata.namespace	It specifies the namespace where this cluster is created.
   spec.clusterName	It specifies the cluster name that this operation is targeted at.
   spec.reconfigure	It specifies a component and its configuration updates.
   spec.reconfigure.componentName	It specifies the component name of this cluster.
   spec.configurations	It contains a list of ConfigurationItem objects, specifying the component's configuration template name, upgrade policy, and parameter key-value pairs to be updated.
   spec.reconfigure.configurations.keys.key	It specifies the configuration map.
   spec.reconfigure.configurations.keys.parameters	It defines a list of key-value pairs for a single configuration file.
   spec.reconfigure.configurations.keys.parameter.key	It represents the name of the parameter you want to edit.
   spec.reconfigure.configurations.keys.parameter.value	It represents the parameter values that are to be updated. If set to nil, the parameter defined by the Key field will be removed from the configuration file.
   spec.reconfigure.configurations.name	It specifies the configuration template name.
   preConditionDeadlineSeconds	It specifies the maximum number of seconds this OpsRequest will wait for its start conditions to be met before aborting. If set to 0 (default), the start conditions must be met immediately for the OpsRequest to proceed.

2. Apply the configuration opsRequest.

   kubectl apply -f mycluster-configuring-demo.yaml -n demo

3. Connect to this cluster to verify whether the configuration takes effect.

   1. Get the username and password.

      kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.username}' | base64 -d
      >
      root
      
      kubectl get secrets -n demo mycluster-conn-credential -o jsonpath='{.data.password}' | base64 -d
      >
      2gvztbvz

   2. Connect to this cluster and verify whether the parameters are configured as expected.

      kubectl exec -ti -n demo mycluster-mysql-0 -- bash
      
      mysql -uroot -p2gvztbvz
      >
      mysql> show variables like 'max_connections';
      +-----------------+-------+
      | Variable_name   | Value |
      +-----------------+-------+
      | max_connections | 600   |
      +-----------------+-------+
      1 row in set (0.00 sec)

note

Just in case you cannot find the configuration file of your cluster, you can switch to the kbcli tab to view the current configuration file of a cluster.