abrt-data *¶

Remove the crash data generated by ABRT.

Remove the automatically generated ABRT crash data in "/var/spool/abrt/".

bash-history *¶

Remove the bash history in the guest.

Remove the bash history of user "root" and any other users who have a ".bash_history" file in their home directory.

Notes on bash-history

Currently this only looks in "/root" and "/home/*" for home directories, so users with home directories in other locations won't have the bash history removed.

blkid-tab *¶

Remove blkid tab in the guest.

ca-certificates¶

Remove CA certificates in the guest.

crash-data *¶

Remove the crash data generated by kexec-tools.

Remove the automatically generated kdump kernel crash data.

cron-spool *¶

Remove user at-jobs and cron-jobs.

delete *¶

Delete specified files or directories.

Delete specified files or directories.

Use the --delete option to specify a path to remove.

You can use shell glob characters in the specified path; note that such metacharacters might require proper escape. For example:

 virt-sysprep --delete '/var/log/*.log'.

dhcp-client-state *¶

Remove DHCP client leases.

dhcp-server-state *¶

Remove DHCP server leases.

dovecot-data *¶

Remove Dovecot (mail server) data.

firewall-rules¶

Remove the firewall rules.

This removes custom firewall rules by removing "/etc/sysconfig/iptables" or custom firewalld configuration in "/etc/firewalld/*/*".

Note this is not enabled by default since it may expose guests to exploits. Use with care.

firstboot *¶

Add scripts to run once at next boot.

Supply one of more shell scripts (using the --firstboot option).

These are run the first time the guest boots, and then are deleted. So these are useful for performing last minute configuration that must run in the context of the guest operating system, for example "yum update".

Output or errors from the scripts are written to "~root/virt-sysprep-firstboot.log" (in the guest).

Notes on firstboot

Currently this is only implemented for Linux guests using either SysVinit-style scripts, Upstart or systemd.

flag-reconfiguration¶

Flag the system for reconfiguration.

Note that this may require user intervention when the guest is booted.

hostname *¶

Change the hostname of the guest.

This operation changes the hostname of the guest to the value given in the --hostname parameter.

If the --hostname parameter is not given, then the hostname is changed to "localhost.localdomain".

Notes on hostname

Currently this can only set the hostname on Linux guests.

kerberos-data¶

Remove Kerberos data in the guest.

logfiles *¶

Remove many log files from the guest.

On Linux the following files are removed:

 /root/anaconda-ks.cfg
 /root/install.log
 /root/install.log.syslog
 /var/cache/fontconfig/*
 /var/cache/gdm/*
 /var/cache/man/*
 /var/lib/AccountService/users/*
 /var/lib/fprint/*
 /var/lib/logrotate.status
 /var/log/*.log*
 /var/log/BackupPC/LOG
 /var/log/apache2/*_log
 /var/log/apache2/*_log-*
 /var/log/audit/*
 /var/log/btmp*
 /var/log/ceph/*.log
 /var/log/chrony/*.log
 /var/log/cron*
 /var/log/cups/*_log
 /var/log/dmesg*
 /var/log/gdm/*
 /var/log/glusterfs/*glusterd.vol.log
 /var/log/glusterfs/glusterfs.log
 /var/log/httpd/*log
 /var/log/jetty/jetty-console.log
 /var/log/lastlog*
 /var/log/libvirt/libvirtd.log
 /var/log/libvirt/lxc/*.log
 /var/log/libvirt/qemu/*.log
 /var/log/libvirt/uml/*.log
 /var/log/mail/*
 /var/log/maillog*
 /var/log/messages*
 /var/log/ntp
 /var/log/ntpstats/*
 /var/log/ppp/connect-errors
 /var/log/sa/*
 /var/log/secure*
 /var/log/setroubleshoot/*.log
 /var/log/spooler*
 /var/log/squid/*.log
 /var/log/tallylog*
 /var/log/wtmp*
 /var/named/data/named.run

lvm-uuids *¶

Change LVM2 PV and VG UUIDs.

On Linux guests that have LVM2 physical volumes (PVs) or volume groups (VGs), new random UUIDs are generated and assigned to those PVs and VGs.

machine-id *¶

Remove the local machine ID.

The machine ID is usually generated from a random source during system installation and stays constant for all subsequent boots. Optionally, for stateless systems it is generated during runtime at boot if it is found to be empty.

mail-spool *¶

Remove email from the local mail spool directory.

net-hostname *¶

Remove HOSTNAME in network interface configuration.

For Fedora and Red Hat Enterprise Linux, this is removed from "ifcfg-*" files.

net-hwaddr *¶

Remove HWADDR (hard-coded MAC address) configuration.

For Fedora and Red Hat Enterprise Linux, this is removed from "ifcfg-*" files.

pacct-log *¶

Remove the process accounting log files.

The system wide process accounting will store to the pacct log files if the process accounting is on.

package-manager-cache *¶

Remove package manager cache.

pam-data *¶

Remove the PAM data in the guest.

password *¶

Set root or user password.

Set root or another user's password.

Use the --root-password option to specify a replacement root password for the guest. You can only use this option once.

Use the --password option to specify replacement user password(s). You can use this option as many times as you want.

Use --password-crypto to change the password encryption used.

See "OPTIONS" above for details of these options.

This operation is enabled by default, but it only does something if there is at least one --root-password or --password argument given.

Notes on password

Currently this only works for glibc-based Linux guests that use shadow passwords.

puppet-data-log *¶

Remove the data and log files of puppet.

random-seed *¶

Generate random seed for guest.

Write some random bytes from the host into the random seed file of the guest.

See "RANDOM SEED" below.

rhn-systemid *¶

Remove the RHN system ID.

rpm-db *¶

Remove host-specific RPM database files.

Remove host-specific RPM database files and locks. RPM will recreate these files automatically if needed.

samba-db-log *¶

Remove the database and log files of Samba.

script *¶

Run arbitrary scripts against the guest.

The "script" module lets you run arbitrary shell scripts or programs against the guest.

Note this feature requires FUSE support. You may have to enable this in your host, for example by adding the current user to the "fuse" group, or by loading a kernel module.

Use one or more --script parameters to specify scripts or programs that will be run against the guest.

The script or program is run with its current directory being the guest's root directory, so relative paths should be used. For example: "rm etc/resolv.conf" in the script would remove a Linux guest's DNS configuration file, but "rm /etc/resolv.conf" would (try to) remove the host's file.

Normally a temporary mount point for the guest is used, but you can choose a specific one by using the --scriptdir parameter.

Note: This is different from --firstboot scripts (which run in the context of the guest when it is booting first time). --script scripts run on the host, not in the guest.

smolt-uuid *¶

Remove the Smolt hardware UUID.

ssh-hostkeys *¶

Remove the SSH host keys in the guest.

The SSH host keys are regenerated (differently) next time the guest is booted.

If, after cloning, the guest gets the same IP address, ssh will give you a stark warning about the host key changing:

 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

ssh-userdir *¶

Remove ".ssh" directories in the guest.

Remove the ".ssh" directory of user "root" and any other users who have a ".ssh" directory in their home directory.

Notes on ssh-userdir

Currently this only looks in "/root" and "/home/*" for home directories, so users with home directories in other locations won't have the ssh files removed.

sssd-db-log *¶

Remove the database and log files of sssd.

tmp-files *¶

Remove temporary files.

This removes temporary files under "/tmp" and "/var/tmp".

udev-persistent-net *¶

Remove udev persistent net rules.

Remove udev persistent net rules which map the guest's existing MAC address to a fixed ethernet device (eg. eth0).

After a guest is cloned, the MAC address usually changes. Since the old MAC address occupies the old name (eg. eth0), this means the fresh MAC address is assigned to a new name (eg. eth1) and this is usually undesirable. Erasing the udev persistent net rules avoids this.

user-account¶

Remove the user accounts in the guest.

Remove all the user accounts and their home directories. The "root" account is not removed.

utmp *¶

Remove the utmp file.

This file records who is currently logged in on a machine. In modern Linux distros it is stored in a ramdisk and hence not part of the virtual machine's disk, but it was stored on disk in older distros.

yum-uuid *¶

Remove the yum UUID.

Yum creates a fresh UUID the next time it runs when it notices that the original UUID has been erased.

COPYING THE BLOCK DEVICE¶

Starting with an original guest, you probably wish to copy the guest block device and its configuration to make a template. Then once you are happy with the template, you will want to make many clones from it.

                        virt-sysprep
                             |
                             v
 original guest --------> template ---------->
                                      \------> cloned
                                       \-----> guests
                                        \---->

You can, of course, just copy the block device on the host using cp(1) or dd(1).

                   dd                 dd
 original guest --------> template ---------->
                                      \------> cloned
                                       \-----> guests
                                        \---->

There are some smarter (and faster) ways too:

                          snapshot
                template ---------->
                            \------> cloned
                             \-----> guests
                              \---->

You may want to run virt-sysprep twice, once to reset the guest (to make a template) and a second time to customize the guest for a specific user:

                    virt-sysprep        virt-sysprep
                      (reset)      (add user, keys, logos)
                         |                   |
                 dd      v          dd       v
 original guest ----> template ---------> copied ------> custom
                                          template       guest

• Create a snapshot using qemu-img:

   qemu-img create -f qcow2 -o backing_file=original snapshot.qcow
      

  The advantage is that you don't need to copy the original (very fast) and only changes are stored (less storage required).

  Note that writing to the backing file once you have created guests on top of it is not possible: you will corrupt the guests.

• Create a snapshot using "lvcreate --snapshot".
• Other ways to create snapshots include using filesystems-level tools (for filesystems such as btrfs).

  Most Network Attached Storage (NAS) devices can also create cheap snapshots from files or LUNs.

• Get your NAS to duplicate the LUN. Most NAS devices can also duplicate LUNs very cheaply (they copy them on-demand in the background).
• Prepare your template using virt-sparsify(1). See below.

VIRT-CLONE¶

A separate tool, virt-clone(1), can be used to duplicate the block device and/or modify the external libvirt configuration of a guest. It will reset the name, UUID and MAC address of the guest in the libvirt XML.

virt-clone(1) does not use libguestfs and cannot look inside the disk image. This was the original motivation to write virt-sysprep.

SPARSIFY¶

              virt-sparsify
 original guest --------> template

virt-sparsify(1) can be used to make the cloning template smaller, making it easier to compress and/or faster to copy.

Notice that since virt-sparsify also copies the image, you can use it to make the initial copy (instead of "dd").

RESIZE¶

                         virt-resize
                template ---------->
                            \------> cloned
                             \-----> guests
                              \---->

If you want to give people cloned guests, but let them pick the size of the guest themselves (eg. depending on how much they are prepared to pay for disk space), then instead of copying the template, you can run virt-resize(1). Virt-resize performs a copy and resize, and thus is ideal for cloning guests from a template.

RANDOM SEED¶

(This section applies to Linux guests only)

The virt-sysprep "random-seed" operation writes a few bytes of randomness from the host into the guest's random seed file.

If this is just done once and the guest is cloned from the same template, then each guest will start with the same entropy, and things like SSH host keys and TCP sequence numbers may be predictable.

Therefore you should arrange to add more randomness after cloning from a template too, which can be done by just enabling the "random-seed" operation:

 cp template.img newguest.img
 virt-sysprep --enable random-seed -a newguest.img

SELINUX RELABELLING¶

(This section applies to Linux guests using SELinux only)

If any new files are created by virt-sysprep, then virt-sysprep touches "/.autorelabel" so that these will be correctly labelled by SELinux the next time the guest is booted. This process interrupts boot and can take some time.

You can force relabelling for all guests by supplying the --selinux-relabel option.

You can disable relabelling entirely by supplying the --no-selinux-relabel option.

Please note that if your guest uses SELinux, and you are doing operations on it which might create new files or change existing ones, you are recommended to use --selinux-relabel. This will help in making sure that files have the right SELinux labels.