[Xen-API] handling "guest tools" versions

[Dave Scott <Dave.Scott@xxxxxxxxxxxxx>]

Hi,

After installing a guest on XCP we usually recommend installing the "guest 
tools". For windows this includes the PV drivers + a user-space agent (the 
agent handles things like clean shutdown requests); for linux this includes 
possibly a kernel update + a user space agent (actually a simple bash script 
which runs from cron and reports stats).

Currently the user space agents write version numbers to xenstore which xapi 
compares with its internal version number and sets a per-VM flag 
PV-drivers-up-to-date. If this flag is false we're basically saying, "please 
upgrade the guest tools just in case something has changed"

Unfortunately when someone makes a VM "appliance", they have to choose an 
arbitrary version number and stick it in there. At some point in the future 
this version will trigger the "please upgrade the guest tools" warning... 
however it's probably not going to be possible to actually upgrade the tools, 
as the appliance may be (should be?) locked down.

To address this I propose that we add an extra flag

/local/domain/<domid>/attr/PVAddons/Immutable

Next to the existing

/local/domain/<domid>/attr/PVAddons/MajorVersion
/local/domain/<domid>/attr/PVAddons/MinorVersion
/local/domain/<domid>/attr/PVAddons/MicroVersion
/local/domain/<domid>/attr/PVAddons/BuildVersion
/local/domain/<domid>/attr/PVAddons/Installed

Which if both present in xenstore and set to "1" will override the 
PV-drivers-up-to-date warning. It will still be possible for clients to see the 
raw version numbers through the API (VM_guest_metrics:PV_drivers_version map) 
but they won't be prompted to take an action which they can't perform and thus 
get annoyed IYSWIM :)

What do you think?

Cheers,
Dave

_______________________________________________
xen-api mailing list
xen-api@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/mailman/listinfo/xen-api