Re: [Users] Linux sysprep

From:Greg Padgett <gpadgett(a)redhat.com&gt; Sent: Monday 19th August 2013 21:16 To: René Koch <r.koch(a)ovido.at&gt; Cc: ovirt-users <users(a)ovirt.org&gt; Subject: Re: [Users] Linux sysprep 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...