Re: [Users] Linux sysprep

On 08/19/2013 04:26 PM, René Koch wrote: > > -----Original message----- >> 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. > > Thanks a lot for your answer - this definitely points me into the right way. > Great, happy to help. > >> >> 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. > > > For some strange reason I totally missed the vm payload feature (and it seems to be introduced already in oVirt 3.1 according to the release notes). > Can I attach a vm payload via webadmin portal of oVirt 3.2 (and if yes - how?) or only via REST-API? > > So if I understand this right, I would do the following: > - use before_vm_start_hook which creates the payload and updates vm xml definition - add <payloads> with e.g. file name "unattended.txt" andcontent "hostname=pool-vm95" > - have script started in host which mounts the floppy, reads the content of unattended.txt and do some magic > Only REST API. It sounds like you're on the right track with it.

> > >> - 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. > > > cloud-init sounds very interesting, but this requires oVirt 3.3, right? > I'm running oVirt 3.2 at the moment. > Yeah, 3.3 for the integrated features. You could use it standalone in 3.2, i.e. attach a config disk you made yourself--but compared to the approach above, the effort might not be worth it considering what you want to accomplish. > > Regards, > René > > >> >> 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... >> >>