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Perform a Canary Upgrade on TiDB Operator

This document describes how to perform a canary upgrade on TiDB Operator. Using canary upgrades, you can prevent normal TiDB Operator upgrade from causing an unexpected impact on all the TiDB clusters in Kubernetes. After you confirm the impact of TiDB Operator upgrade or that the upgraded TiDB Operator works stably, you can normally upgrade TiDB Operator.

Note:

  • You can perform a canary upgrade only on tidb-controller-manager and tidb-scheduler. AdvancedStatefulSet controller and tidb-admission-webhook do not support the canary upgrade.
  • Canary upgrade is supported since v1.1.10. The version of your current TiDB Operator should be >= v1.1.10.

To support canary upgrade, some parameters are added to the values.yaml file in the tidb-operator chart. See Related parameters for details.

Canary upgrade process

  1. Configure selector for the current TiDB Operator:

    Refer to Upgrade TiDB Operator. Add the following configuration in the values.yaml file, and upgrade TiDB Operator:

    controllerManager:
      selector:
      - version!=canary

    If you have already performed the step above, skip to Step 2.

  2. Deploy the canary TiDB Operator:

    Refer to Deploy TiDB Operator. Add the following configuration in the values.yaml file, and deploy the canary TiDB Operator in a different namespace (such as tidb-admin-canary) with a different Helm Release Name (such as helm install tidb-operator-canary ...):

    controllerManager:
      selector:
      - version=canary
    appendReleaseSuffix: true
    #scheduler:
    #  create: false
    advancedStatefulset:
      create: false
    admissionWebhook:
      create: false

    Note:

    • It is recommended to deploy the new TiDB Operator in a separate namespace.
    • Set appendReleaseSuffix to true.
    • If you do not need to perform a canary upgrade on tidb-scheduler, configure scheduler.create: false.
    • If you configure scheduler.create: true, a scheduler named {{ .scheduler.schedulerName }}-{{.Release.Name}} will be created. To use this scheduler, configure spec.schedulerName in the TidbCluster CR to the name of this scheduler.
    • You need to set advancedStatefulset.create: false and admissionWebhook.create: false, because AdvancedStatefulSet controller and tidb-admission-webhook do not support the canary upgrade.
  3. To test the canary upgrade of tidb-controller-manager, set labels for a TiDB cluster by running the following command:

    kubectl -n ${namespace} label tc ${cluster_name} version=canary

    Check the logs of the two deployed tidb-controller-managers, and you can see this TiDB cluster is now managed by the canary TiDB Operator:

    1. View the log of tidb-controller-manager of the current TiDB Operator:

      kubectl -n tidb-admin logs tidb-controller-manager-55b887bdc9-lzdwv
      I0305 07:52:04.558973       1 tidb_cluster_controller.go:148] TidbCluster has been deleted tidb-cluster-1/basic1
    2. View the log of tidb-controller-manager of the canary TiDB Operator:

      kubectl -n tidb-admin-canary logs tidb-controller-manager-canary-6dcb9bdd95-qf4qr
      I0113 03:38:43.859387       1 tidbcluster_control.go:69] TidbCluster: [tidb-cluster-1/basic1] updated successfully
  4. To test the canary upgrade of tidb-scheduler, modify spec.schedulerName of some TiDB cluster to tidb-scheduler-canary by running the following command:

    kubectl -n ${namespace} edit tc ${cluster_name}

    After the modification, all components in the cluster will be rolling updated.

    Check the logs of tidb-scheduler of the canary TiDB Operator, and you can see this TiDB cluster is now using the canary tidb-scheduler:

    kubectl -n tidb-admin-canary logs tidb-scheduler-canary-7f7b6c7c6-j5p2j -c tidb-scheduler
  5. After the tests, you can revert the changes in Step 3 and Step 4 so that the TiDB cluster is again managed by the current TiDB Operator.

    kubectl -n ${namespace} label tc ${cluster_name} version-
    kubectl -n ${namespace} edit tc ${cluster_name}
  6. Delete the canary TiDB Operator:

    helm -n tidb-admin-canary uninstall ${release_name}
  7. Refer to Upgrade TiDB Operator and upgrade the current TiDB Operator normally.