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GuestAgent

Revision as of 23:29, 17 February 2013 by Ryan Lane (talk | contribs) (Text replace - "__NOTOC__" to "")

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': '<command_name>', 'value': '<command_args>'}"


Responses are:

"{'returncode': '<response_code>', 'message': '<response_string>'}"


Current commands on Guest Agents (Linux/Windows):

Description Command Command Arguments Response Code
Get version info from the agent "version" "agent" or "xentools" or "updater" "0"
Get a list of agent features "features" "" "0"
Do a Diffie-Hellman Key Exchange "keyinit" local public key "D0"
(Re)set root password "password" encrypted password "0"
Configure the networking "resetnetwork" "" "0"
Update the agent "agentupdate" "URL,MD5SUM" "0"
Inject a file "injectfile" base64 encoding of "file_path,file_contents" "0"
Guest is ready/available?
Update XenTools (Windows only)
KMS Licensing (Windows only)

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

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

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)

Test/Demo Plan