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Enable system rollbacks for your Managed Service for Apache Flink application - Managed Service for Apache Flink
How it worksReview common scenarios for automatic system rollbackUse operation APIs for system rollbacks

Enable system rollbacks for your Managed Service for Apache Flink application

With system-rollback capability, you can achieve higher availability of your running Apache Flink application on Amazon Managed Service for Apache Flink. Opting into this configuration enables the service to automatically revert the application to the previously running version when an action such as UpdateApplication or autoscaling runs into code or configurations bugs.

Note

To use the system rollback feature, you must opt in by updating your application. Existing applications will not automatically use system rollback by default.

How it works

When you initiate an application operation, such as an update or scaling action, the Amazon Managed Service for Apache Flink first attempts to run that operation. If it detects issues that prevent the operation from succeeding, such as code bugs or insufficient permissions, the service automatically initiates a RollbackApplication operation.

The rollback attempts to restore the application to the previous version that ran successfully, along with the associated application state. If the rollback is successful, your application continues processing data with minimal downtime using the previous version. If the automatic rollback also fails, Amazon Managed Service for Apache Flink transitions the application to the READY status, so that you can take further actions, including fixing the error and retrying the operation.

Whether the application uses enhanced snapshot mode determines which snapshot a system rollback restores:

  • Enhanced snapshot mode: Managed Service for Apache Flink restores the newest READY enhanced snapshot of the application. When an update starts and SnapshotsEnabled is true, Managed Service for Apache Flink creates a system snapshot of the previous application version before it applies the update. If that system snapshot is READY, it is the newest enhanced snapshot, and the rollback restores it. If the application has no READY enhanced snapshot, the rollback fails. For more information, see Roll back an application.

  • Application snapshots (legacy): Managed Service for Apache Flink restores the newest READY application snapshot (legacy) at or earlier than the previous application version.

You must opt in to use automatic system rollbacks. You can enable it using the console or API for all operations on your application from this point forward.

The following example request for the UpdateApplication action enables system rollbacks for an application:

{
   "ApplicationName": "MyApplication",
   "CurrentApplicationVersionId": 1,
   "ApplicationConfigurationUpdate": { 
      "ApplicationSystemRollbackConfigurationUpdate": { 
         "RollbackEnabledUpdate": "true"
       }
    }
}

Review common scenarios for automatic system rollback

The following scenarios illustrate where automatic system rollbacks are beneficial:

  • Application updates: If you update your application with new code that has bugs when initializing the Flink job through the main method, the automatic rollback allows the previous working version to be restored. Other update scenarios where system rollbacks are helpful include:

    • If your application is updated to run with a parallelism higher than maxParallelism.

    • If your application is updated to run with incorrect subnets for a VPC application that results in a failure during the Flink job startup.

  • Flink version upgrades: When you upgrade to a new Apache Flink version and the upgraded application encounters a snapshot compatibility issue, system rollback lets you revert to the prior Flink version automatically.

  • AutoScaling: When the application scales up but runs into issues restoring from a savepoint, due to operator mismatch between the snapshot and the Flink job graph.

  • Upgrade to enhanced snapshot mode: If the application fails to restart after the upgrade, the system rollback restores the version before the upgrade. The application uses application snapshots (legacy) again. For more information, see Roll back after the upgrade.

Use operation APIs for system rollbacks

To provide better visibility, Amazon Managed Service for Apache Flink has two APIs related to application operations that can help you track failures and related system rollbacks.

ListApplicationOperations

This API lists all operations performed on the application, including UpdateApplication, Maintenance, RollbackApplication, and others in reverse chronological order. The following example request for the ListApplicationOperations action lists the first 10 application operations for the application:

{
   "ApplicationName": "MyApplication",
   "Limit": 10
}

This following example request for ListApplicationOperations helps filter the list to previous updates on the application:

{
   "ApplicationName": "MyApplication",
   "operation": "UpdateApplication"
}

DescribeApplicationOperation

This API provides detailed information about a specific operation listed by ListApplicationOperations, including the reason for failure, if applicable. The following example request for the DescribeApplicationOperation action lists details for a specific application operation:

{
   "ApplicationName": "MyApplication",
   "OperationId": "xyzoperation"
}

For troubleshooting information, see System rollback best practices.