RescueMode

• Launchpad Entry: NovaSpec:rescue-mode
• Created: 2010-09-01
• Contributors: JesseAndrews

Summary

An instance's filesystem could become corrupted with prolonged usage. Rescue mode provides a mechanism for access even when the VM's image renders the instance inaccessible.

Release Note

A method has been added to OpenStack compute to reboot a virtual machine in rescue mode. A rescue VM is launched that allows a user to fix their VM (by accessing with a new root password).

Rationale

Rackspace/Slicehost parity

User stories

A user deleted a crucial file needed to launch a VM as they found out after they rebooted. The user was able to reboot in rescue mode and restore the original file.

Assumptions

• rescue VM is given the same network configuration as real VM
• a new root username/password is generated
• a new API method is needed since Cloud Servers Developer Guide (API v1) doesn't include a rescue mode
• a rescue image would be provided (the image id woudl be a nova configuration option)

Design

When the API method is called:

• VM is marked in rescue mode
• VM is shutdown
• a new VM is created with identical network configuration but a new root password
• the new VM has a rescue image as the primary filesystem and the secondary filesystem would be the original VM's primary filesystem
• when the rescue machine is shutdown, the original VM is respawned with any changes

Implementation

A new API method seems to be required (pvo?).

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