9:16 p.m.
On 08/19/2013 10:17 AM, René Koch (ovido) wrote:
Hi,
Has anyone an idea what's the easiest way to sysprep Linux (CentOS 6 and
RHEL 6) machines?
The use case is the following: I want to create a lot of virtual
machines (e.g. 100) by cloning from one template.
So I create a master vm, create a template and a pool with 100 vms
assigned to it and set all 100 vms to prestarted.
The problem is now, that when I run "sys-unconfig" before creating the
template, which does a "touch /.unconfigured" I have to go through the
sysconfig-tui and set a new root password for all 100 hosts.
So what I'm looking for is a script like the sysprep tool for windows
which sets parameters for me automatically.
I only need to change:
* Hostname + set DHCP_HOSTNAME in ifcfg-eth0 (Hostname == Pool-VM-Name)
for some dhcp/ddns magic :)
* Clear udev network-rules
* remove SSH-Keys
* Remove RHN ID and join Satellite/Spacewalk-server
* root-password,... should stay the same
My first question is: does oVirt provide such a functionality for Linux
guest out-of-the-box? I couldn't find one.
I think I could solve this with virt-sysprep and virt-file, but I'm
unsure if I can use it with oVirt (or only with plain libvirt):
http://libguestfs.org/virt-sysprep.1.html
http://libguestfs.org/virt-edit.1.html
For this tools it's required that the vm is not running, as it changes
files on the disk. If I'm using a before-vm-start hook, it should be
save to access the disk and change content with virt-sysprep/virt-file,
right?
But do I have access to the disk in a before-vm-start hook?
If using NFS storage I should be able to access all disks on the
NFS-share, but for iSCSI/FC-LUNS - are they available on the hypervisor
in this stage?
Another option would be to write a custom script which is started during
boot and disables itself after successful run (in the same way as
firstboot - I already have such a script for RHN Satellite/Spacewalk
joins). The problem here is: How do I get the (oVirt) name of this vm
(would need something like virt-whoami :) )? Is the (internal oVirt) ID
of this vm stored somewhere in the filesystem of this vm? I don't think
so....
Thanks a lot for suggestions,
René
Hi René,
You may be able to accomplish at least some of what you want using
Cloud-Init, some features of which we've integrated into oVirt [1]. It
went in recently so may not be in whichever version you're running, but
you can probably borrow some of the concepts to get the job done.
Just a few ideas:
- create a vm payload [2] and attach it to the VM which can hold your
config info e.g. vm name, which a custom script could pick up. No need
for the latest oVirt with this option.
- create a Cloud-Init config disk yourself and attach it as a payload,
and let Cloud-Init do the initialization. There are several formats;
oVirt uses Config-Drive-v2. Example at [3]. Depending on the config disk
format, you may need the latest oVirt/vdsm to assign a volume label to the
vm payload.
- use the latest oVirt and its Cloud-Init functionality; for fields not
handled, attach a file and let a script handle it.
HTH,
Greg
[1] http://www.ovirt.org/Features/Cloud-Init_Integration
[2] http://www.ovirt.org/Features/VMPayload
[3]
http://docs.openstack.org/trunk/openstack-compute/admin/content/config-dr...