OpenStack Nova Instances’ Task States

OpenStack Nova, an integral component of the OpenStack cloud computing platform, orchestrates compute instances. A critical aspect of managing these instances is understanding their task_state. This attribute provides a real-time view of what operations are being performed on an instance. In this article, we’ll delve into the various task_state values, offering a comprehensive guide to what each state signifies.

1. NULL

Default State: When an instance is not undergoing any specific task, its task_state is set to NULL. This is the resting state of an instance when it is neither being created, modified, nor deleted.

2. scheduling

Initiation of Creation: This state indicates that the instance creation process has started. The scheduler is actively working to determine which compute node should host the instance.

3. block_device_mapping

Storage Configuration: At this stage, Nova is configuring block storage devices for the instance. This involves attaching volumes and setting up any necessary storage parameters.

4. networking

Network Setup: Here, the instance is having its network configurations set up, which includes assigning IP addresses and configuring network interfaces.

5. spawning

Launch Process: The instance is being actively launched. This involves loading the instance onto the compute node and starting it up.

6. image_snapshot

Snapshot Creation: Indicates that a snapshot of the instance is being created. This is often used for backup or for creating a template for new instances.

7. image_snapshot_pending

Snapshot Queuing: A snapshot creation request has been made, but the process has not yet started.

8. image_pending_upload

Awaiting Snapshot Upload: Post-snapshot creation, this state implies the snapshot is waiting to be uploaded to the image service.

9. image_uploading

Snapshot Uploading: The snapshot is currently being uploaded to the image service.

10. image_backup

Image Backup: This state is active when a backup of the instance’s image is being created.

11. updating_password

Password Update: This state is seen when the instance’s password is being updated, either as part of an automated process or a manual update.

12. resize_prep

Pre-Resize Configuration: Before resizing an instance, certain preparatory steps are taken – this state reflects that phase.

13. resize_migrating

Resize-Driven Migration: When an instance is resized, it may require migration to a different host. This state indicates that such a migration is in progress.

14. resize_migrated

Post-Migration Resize: Once the migration part of a resize operation is complete, this state is set, indicating the instance is ready for the next steps in the resizing process.

15. resize_finish

Finalizing Resize: This state signifies the final steps in the instance resizing process.

16. resize_reverting

Reversing Resize: If a resize operation is reversed or fails, the instance enters this state during the rollback process.

17. resize_confirming

Resize Confirmation: This state is active when the system is in the process of confirming a resize operation, typically requiring an explicit confirmation from the user.

18. rebooting, reboot_pending, reboot_started, reboot_completed

Reboot Phases: These states reflect the different stages of an instance reboot, from initiation to completion.

19. pausing, unpausing

Pause Operations: These states are active when an instance is being paused or unpaused. Pausing an instance is like suspending it, but it retains its state in RAM.

20. suspending, resuming

Suspension and Resumption: Similar to pause, but in this case, the instance’s state is saved to disk, allowing it to be moved or its resources reallocated.

21. powering-off, powering-on

Power Management: These states indicate the process of powering an instance off or on, similar to turning a physical machine on or off.

22. rescuing, unrescuing

Rescue Mode: Rescue mode is used for troubleshooting. These states are active when an instance is being put into or taken out of rescue mode.

23. rebuilding

Instance Rebuild: This state indicates that an instance is being rebuilt, which could involve changing its image or other key settings.

24. rebuild_block_device_mapping and rebuild_spawning

Rebuild Sub-Stages: These are specific stages within the rebuilding process, handling storage and launch aspects, respectively.

25. migrating

Host Migration: This state is active when an instance is being migrated from one host to another, often for load balancing or hardware maintenance.

26. deleting

Instance Deletion: Indicates that the instance is in the process of being permanently deleted.

27. soft-deleting

Soft Deletion: This state allows for the instance to be restored later, as opposed to being permanently deleted.

28. restoring

Restoring from Soft-Delete: This state is active when a soft-deleted instance is being restored to active status.

29. shelving, shelving_image_pending_upload, shelving_image_uploading, shelved, shelved_offloaded

Shelving Operations: These states are related to the process of shelving (temporarily decommissioning) an instance, including stages for image upload and offloading from the compute node.

30. error

Error State: This state signifies that an error has occurred during the previous operation. It requires investigation to determine the cause and necessary corrective action.

Understanding these task_state values is crucial for anyone involved in managing OpenStack environments. They provide detailed insights into the operational status of instances, enabling administrators to effectively monitor, manage, and troubleshoot their cloud infrastructure.