GuestAgent


 * Launchpad Entry: NovaSpec:resize-servers
 * Created: 2010-09-01
 * Contributors: JesseAndrews, ChrisBehrens

Summary
The feature will allow communication with a guest agent from compute node controller. This allows cloud controller APIs to be added for user controlled password reset, settings ips, ... - allowing windows support.

Design Summit Notes
Live Notes were be taken for this topic at: http://etherpad.openstack.org/GuestAgent

Current architecture of the Rackspace Guest Agents
App -> Host (XenStore) <-> Guest Agent

See the GuestAgentXenStoreCommunication wiki entry for more information. Details about the 'protocol' used for the XenStore communication is contained there. Requests and responses are encoded in JSON.

The format of the requests are:

"{'name': '', 'value': ''}"

Responses are:

"{'returncode': '', 'message': ''}"

Current commands on Guest Agents (Linux/Windows):

Considerations
1. What happens when a client/customer kills the guest agent or disables the startup? 2. Agents should be hypervisor agnostic/support many hypervisors


 * Launchpad Entry: NovaSpec:resize-servers
 * Created: 2010-09-01
 * Contributors: JesseAndrews

Summary
The feature will allow communication with a guest agent from compute node controller. This allows cloud controller APIs to be added for user controlled password reset, settings ips, ... - allowing windows support.

Release Note
Support has been added to OpenStack compute host agent code to support communication with guest agents.

Rationale
Windows instances cannot be configured similarly to linux machines. Supporting them as well as tools that provide for better user experience (such as password reset) provide rackspace/slicehost parity.

User stories
A user forgets their password. Rather than having to use rescue mode to reset the password, the user may have the password reset by using an API.

Assumptions

 * guest agent code for both Unix and Windows is available and licensed under Apache 2.0. They're available at https://launchpad.net/openstack-guest-agents

Design
To communicate with guest agents, we use the XenStore in XenServer.

Implementation
API additions:
 * reset password

Messages are written to XenStore using xenstore-write for each instance via /local/domain/(domid)/data/guest/(message_uuid)