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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.

View parameter information​

View the current configuration file of a cluster.

kbcli cluster describe-config pg-cluster

From the meta information, you can find the configuration files of this PostgreSQL cluster.

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

  • View the details of the current configuration file.

    kbcli cluster describe-config pg-cluster --show-detail

  • View the parameter description.

    kbcli cluster explain-config pg-cluster | head -n 20

  • View the user guide of a specified parameter.

    kbcli cluster explain-config pg-cluster --param=max_connections
    Output
    template meta:
      ConfigSpec: postgresql-configuration ComponentName: postgresql ClusterName: pg-cluster

    Configure Constraint:
      Parameter Name:     max_connections
      Allowed Values:     [6-8388607]
      Scope:              Global
      Dynamic:            true
      Type:               integer
      Description:        Sets the maximum number of concurrent connections.
    • 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 as an example.

  1. View the current values of max_connections.

    kbcli cluster connect pg-cluster
    postgres=# show max_connections;
     max_connections
    -----------------
     100
    (1 row)

  2. Adjust the values of max_connections.

    kbcli cluster configure pg-cluster --set=max_connections=200
    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 pg-cluster  --set=max_connections=5
    error: failed to validate updated config: [failed to cue template render configure: [pg.acllog-max-len: invalid value 5 (out of bound 6-8388607):
     343:34
    ]
    ]

  3. View the status of the parameter configuration.

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

    When the Status.Status shows Succeed, the configuration is completed.

    kbcli cluster describe-ops pg-cluster-reconfiguring-fq6q7 -n default
    Output
    Spec:
      Name: pg-cluster-reconfiguring-fq6q7 NameSpace: default Cluster: pg-cluster Type: Reconfiguring

    Command:
      kbcli cluster configure pg-cluster --components=postgresql --config-specs=postgresql-configuration --config-file=postgresql.conf --set max_connections=100 --namespace=default

    Status:
      Start Time:         Mar 17,2023 19:25 UTC+0800
      Completion Time:    Mar 17,2023 19:25 UTC+0800
      Duration:           2s
      Status:             Succeed
      Progress:           1/1
                          OBJECT-KEY   STATUS   DURATION   MESSAGE

    Conditions:
    LAST-TRANSITION-TIME         TYPE                 REASON                            STATUS   MESSAGE
    Mar 17,2023 19:25 UTC+0800   Progressing          OpsRequestProgressingStarted      True     Start to process the OpsRequest: pg-cluster-reconfiguring-fq6q7 in Cluster: pg-cluster
    Mar 17,2023 19:25 UTC+0800   Validated            ValidateOpsRequestPassed          True     OpsRequest: pg-cluster-reconfiguring-fq6q7 is validated
    Mar 17,2023 19:25 UTC+0800   Reconfigure          ReconfigureStarted                True     Start to reconfigure in Cluster: pg-cluster, Component: postgresql
    Mar 17,2023 19:25 UTC+0800   ReconfigureMerged    ReconfigureMerged                 True     Reconfiguring in Cluster: pg-cluster, Component: postgresql, ConfigSpec: postgresql-configuration, info: updated: map[postgresql.conf:{"max_connections":"200"}], added: map[], deleted:map[]
    Mar 17,2023 19:25 UTC+0800   ReconfigureSucceed   ReconfigureSucceed                True     Reconfiguring in Cluster: pg-cluster, Component: postgresql, ConfigSpec: postgresql-configuration, info: updated policy: <operatorSyncUpdate>, updated: map[postgresql.conf:{"max_connections":"100"}], added: map[], deleted:map[]
    Mar 17,2023 19:25 UTC+0800   Succeed              OpsRequestProcessedSuccessfully   True     Successfully processed the OpsRequest: pg-cluster-reconfiguring-fq6q7 in Cluster: pg-cluster

  4. Connect to the database to verify whether the parameter is configured as expected.

    The whole searching process has a 30-second delay since it takes some time for kubelet to synchronize modifications to the volume of the pod.

    kbcli cluster connect pg-cluster
    postgres=# show max_connections;
     max_connections
    -----------------
     200
    (1 row)

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 pg-cluster
    note

    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 xxx -n default

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

    kbcli cluster connect pg-cluster
    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 pg-cluster
Output
ConfigSpecs Meta:
CONFIG-SPEC-NAME            FILE                  ENABLED   TEMPLATE                    CONSTRAINT        RENDERED                                          COMPONENT    CLUSTER
postgresql-configuration    kb_restore.conf       false     postgresql-configuration    postgresql14-cc   pg-cluster-postgresql-postgresql-configuration    postgresql   pg-cluster
postgresql-configuration    pg_hba.conf           false     postgresql-configuration    postgresql14-cc   pg-cluster-postgresql-postgresql-configuration    postgresql   pg-cluster
postgresql-configuration    postgresql.conf       true      postgresql-configuration    postgresql14-cc   pg-cluster-postgresql-postgresql-configuration    postgresql   pg-cluster
postgresql-configuration    kb_pitr.conf          false     postgresql-configuration    postgresql14-cc   pg-cluster-postgresql-postgresql-configuration    postgresql   pg-cluster
postgresql-custom-metrics   custom-metrics.yaml   false     postgresql-custom-metrics                     pg-cluster-postgresql-postgresql-custom-metrics   postgresql   pg-cluster

History modifications:
OPS-NAME                         CLUSTER      COMPONENT    CONFIG-SPEC-NAME           FILE              STATUS    POLICY    PROGRESS   CREATED-TIME                 VALID-UPDATED
pg-cluster-reconfiguring-fq6q7   pg-cluster   postgresql   postgresql-configuration   postgresql.conf   Succeed             1/1        Mar 17,2023 19:25 UTC+0800   {"postgresql.conf":"{\"max_connections\":\"100\"}"}
pg-cluster-reconfiguring-bm84z   pg-cluster   postgresql   postgresql-configuration   postgresql.conf   Succeed             1/1        Mar 17,2023 19:27 UTC+0800   {"postgresql.conf":"{\"max_connections\":\"200\"}"}
pg-cluster-reconfiguring-cbqxd   pg-cluster   postgresql   postgresql-configuration   postgresql.conf   Succeed             1/1        Mar 17,2023 19:35 UTC+0800   {"postgresql.conf":"{\"max_connections\":\"500\"}"}
pg-cluster-reconfiguring-rcnzb   pg-cluster   postgresql   postgresql-configuration   postgresql.conf   Succeed   restart   1/1        Mar 17,2023 19:38 UTC+0800   {"postgresql.conf":"{\"shared_buffers\":\"512MB\"}"}

From the above results, there are three parameter modifications.

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

kbcli cluster diff-config pg-cluster-reconfiguring-bm84z pg-cluster-reconfiguring-rcnzb
>
DIFF-CONFIG RESULT:
  ConfigFile: postgresql.conf TemplateName: postgresql-configuration ComponentName: postgresql ClusterName: pg-cluster UpdateType: update

PARAMETERNAME     PG-CLUSTER-RECONFIGURING-BM84Z   PG-CLUSTER-RECONFIGURING-RCNZB
max_connections   200                              500
shared_buffers    256MB                            512MB