virt-sysprep1

Usage

Warning

Using "virt-sysprep" on live virtual machines, or concurrently with other disk editing tools, can be dangerous, potentially causing disk corruption. The virtual machine must be shut down before you use this command, and disk images must not be edited concurrently.

Overview

Virt-sysprep can reset or unconfigure a virtual machine so that clones can be made from it, or to prepare a template from which clones can be made later on. Steps in this process include removing SSH host keys, removing persistent network MAC configuration, and removing user accounts. Virt-sysprep can also customize a virtual machine, for instance by adding SSH keys, users or logos. Each step can be enabled or disabled as required.

Virt-sysprep modifies the guest or disk image in place. The guest must be shut down. If you want to preserve the existing contents of the guest, you must snapshot, copy or clone the disk first.

You do not need to run virt-sysprep as root. In fact we'd generally recommend that you don't. The time you might want to run it as root is when you need root in order to access the disk image, but even in this case it would be better to change the permissions on the disk image to be writable as the non-root user running virt-sysprep.

"Sysprep" stands for "system preparation" tool. The name comes from the Microsoft program sysprep.exe which is used to unconfigure Windows machines in preparation for cloning them. (Virt-sysprep does not work on Microsoft Windows guests.)

Options

--help

Display brief help.

-a file

--add file

Add file which should be a disk image from a virtual machine.

The format of the disk image is auto-detected. To override this and force a particular format use the --format option.

-a URI

--add URI

Add a remote disk. The URI format is compatible with guestfish. See "ADDING REMOTE STORAGE" in guestfish(1).

--colors

--colours

Use ANSI colour sequences to colourize messages. This is the default when the output is a tty. If the output of the program is redirected to a file, ANSI colour sequences are disabled unless you use this option.

-c URI

--connect URI

If using libvirt, connect to the given URI. If omitted, then we connect to the default libvirt hypervisor.

If you specify guest block devices directly (-a), then libvirt is not used at all.

-d guest

--domain guest

Add all the disks from the named libvirt guest. Domain UUIDs can be used instead of names.

-n

--dry-run

Perform a read-only "dry run" on the guest. This runs the sysprep operation, but throws away any changes to the disk at the end.

--enable operations

Choose which sysprep operations to perform. Give a comma-separated list of operations, for example:

 --enable ssh-hostkeys,udev-persistent-net

would enable ONLY "ssh-hostkeys" and "udev-persistent-net" operations.

If the --enable option is not given, then we default to trying most sysprep operations (see --list-operations to show which are enabled).

Regardless of the --enable option, sysprep operations are skipped for some guest types.

Use --list-operations to list operations supported by a particular version of virt-sysprep.

See "OPERATIONS" below for a list and an explanation of each operation.

--operation operations

--operations operations

Choose which sysprep operations to perform. Give a comma-separated list of operations, for example:

 --operations ssh-hostkeys,udev-persistent-net

would enable ONLY "ssh-hostkeys" and "udev-persistent-net" operations.

--operations allows you to enable and disable any operation, including the default ones (which would be tried when specifying neither --operations nor --enable) and all the available ones; prepending a "-" in front of an operation name removes it from the list of enabled operations, while the meta-names "defaults" and "all" represent respectively the operations enabled by default and all the available ones. For example:

 --operations firewall-rules,defaults,-tmp-files

would enable the "firewall-rules" operation (regardless whether it is enabled by default), all the default ones, and disable the "tmp-files" operation.

--operations can be specified multiple times; the first time the set of enabled operations is empty, while any further --operations affects the operations enabled so far.

If the --operations option is not given, then we default to trying most sysprep operations (see --list-operations to show which are enabled).

Regardless of the --operations option, sysprep operations are skipped for some guest types.

Use --list-operations to list operations supported by a particular version of virt-sysprep.

See "OPERATIONS" below for a list and an explanation of each operation.

--echo-keys

When prompting for keys and passphrases, virt-sysprep normally turns echoing off so you cannot see what you are typing. If you are not worried about Tempest attacks and there is no one else in the room you can specify this flag to see what you are typing.

--format raw|qcow2|..

--format auto

The default for the -a option is to auto-detect the format of the disk image. Using this forces the disk format for -a options which follow on the command line. Using --format auto switches back to auto-detection for subsequent -a options.

For example:

 virt-sysprep --format raw -a disk.img

forces raw format (no auto-detection) for disk.img.

 virt-sysprep --format raw -a disk.img --format auto -a another.img

forces raw format (no auto-detection) for disk.img and reverts to auto-detection for another.img.

If you have untrusted raw-format guest disk images, you should use this option to specify the disk format. This avoids a possible security problem with malicious guests (CVE-2010-3851).

--key SELECTOR

Specify a key for LUKS, to automatically open a LUKS device when using the inspection.

--key NAME:key:KEY_STRING

--key UUID:key:KEY_STRING

--key all:key:KEY_STRING

"NAME" is the libguestfs device name (eg. "/dev/sda1"). "UUID" is the device UUID. "all" means try the key against any encrypted device.

Use the specified "KEY_STRING" as passphrase.

--key NAME:file:FILENAME

--key UUID:file:FILENAME

--key all:file:FILENAME

Read the passphrase from FILENAME.

--key NAME:clevis

--key UUID:clevis

--key all:clevis

Attempt passphrase-less unlocking for the device with Clevis, over the network. Please refer to "ENCRYPTED DISKS" in guestfs(3) for more information on network-bound disk encryption (NBDE).

Note that if any such option is present on the command line, QEMU user networking will be automatically enabled for the libguestfs appliance.

--keys-from-stdin

Read key or passphrase parameters from stdin. The default is to try to read passphrases from the user by opening /dev/tty.

If there are multiple encrypted devices then you may need to supply multiple keys on stdin, one per line.

--list-operations

List the operations supported by the virt-sysprep program.

These are listed one per line, with one or more single-space-separated fields, eg:

 $ virt-sysprep --list-operations
 bash-history * Remove the bash history in the guest
 cron-spool * Remove user at-jobs and cron-jobs
 dhcp-client-state * Remove DHCP client leases
 dhcp-server-state * Remove DHCP server leases
 [etc]

The first field is the operation name, which can be supplied to --enable. The second field is a "*" character if the operation is enabled by default or blank if not. Subsequent fields on the same line are the description of the operation.

Before libguestfs 1.17.33 only the first (operation name) field was shown and all operations were enabled by default.

--mount-options mp:opts[;mp:opts;...]

Set the mount options used when libguestfs opens the disk image. Note this has no effect on the guest. It is used when opening certain guests such as ones using the UFS (BSD) filesystem.

Use a semicolon-separated list of "mountpoint:options" pairs. You may need to quote this list to protect it from the shell.

For example:

 --mount-options "/:noatime"

will mount the root directory with "notime". This example:

 --mount-options "/:noatime;/var:rw,nodiratime"

will do the same, plus mount /var with "rw,nodiratime".

-q

--quiet

Don’t print log messages.

To enable detailed logging of individual file operations, use -x.

--network

--no-network

Enable or disable network access from the guest during the installation.

In virt-sysprep, the network is disabled by default. You must use --network to enable it, in order that options such as --install or --update will work.

virt-builder(1) has more information about the security advantages of disabling the network.

-v

--verbose

Enable verbose messages for debugging.

-V

--version

Display version number and exit.

--wrap

Wrap error, warning, and informative messages. This is the default when the output is a tty. If the output of the program is redirected to a file, wrapping is disabled unless you use this option.

-x

Enable tracing of libguestfs API calls.

--append-line FILE:LINE (see "customize" below)

Append a single line of text to the "FILE". If the file does not already end with a newline, then one is added before the appended line. Also a newline is added to the end of the "LINE" string automatically.

For example (assuming ordinary shell quoting) this command:

 --append-line '/etc/hosts:10.0.0.1 foo'

will add either "10.0.0.1 foo⏎" or "⏎10.0.0.1 foo⏎" to the file, the latter only if the existing file does not already end with a newline.

"⏎" represents a newline character, which is guessed by looking at the existing content of the file, so this command does the right thing for files using Unix or Windows line endings. It also works for empty or non-existent files.

To insert several lines, use the same option several times:

 --append-line '/etc/hosts:10.0.0.1 foo'
 --append-line '/etc/hosts:10.0.0.2 bar'

To insert a blank line before the appended line, do:

 --append-line '/etc/hosts:'
 --append-line '/etc/hosts:10.0.0.1 foo'

--chmod PERMISSIONS:FILE (see "customize" below)

Change the permissions of "FILE" to "PERMISSIONS".

Note: "PERMISSIONS" by default would be decimal, unless you prefix it with 0 to get octal, ie. use 0700 not 700.

--chown UID:GID:PATH (see "customize" below)

Change the owner user and group ID of a file or directory in the guest. Note:

•

Only numeric UIDs and GIDs will work, and these may not be the same inside the guest as on the host.

•

This will not work with Windows guests.

For example:

 virt-customize --chown '0:0:/var/log/audit.log'

See also: --upload.

--commands-from-file FILENAME (see "customize" below)

Read the customize commands from a file, one (and its arguments) each line.

Each line contains a single customization command and its arguments, for example:

 delete /some/file
 install some-package
 password some-user:password:its-new-password

Empty lines are ignored, and lines starting with "#" are comments and are ignored as well. Furthermore, arguments can be spread across multiple lines, by adding a "\" (continuation character) at the of a line, for example

 edit /some/file:\
   s/^OPT=.*/OPT=ok/

The commands are handled in the same order as they are in the file, as if they were specified as --delete /some/file on the command line.

--copy SOURCE:DEST (see "customize" below)

Copy files or directories recursively inside the guest.

Wildcards cannot be used.

--copy-in LOCALPATH:REMOTEDIR (see "customize" below)

Copy local files or directories recursively into the disk image, placing them in the directory "REMOTEDIR" (which must exist).

Wildcards cannot be used.

--delete PATH (see "customize" below)

Delete a file from the guest. Or delete a directory (and all its contents, recursively).

You can use shell glob characters in the specified path. Be careful to escape glob characters from the host shell, if that is required. For example:

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

See also: --upload, --scrub.

--edit FILE:EXPR (see "customize" below)

Edit "FILE" using the Perl expression "EXPR".

Be careful to properly quote the expression to prevent it from being altered by the shell.

Note that this option is only available when Perl 5 is installed.

See "NON-INTERACTIVE EDITING" in virt-edit(1).

--firstboot SCRIPT (see "customize" below)

Install "SCRIPT" inside the guest, so that when the guest first boots up, the script runs (as root, late in the boot process).

The script is automatically chmod +x after installation in the guest.

The alternative version --firstboot-command is the same, but it conveniently wraps the command up in a single line script for you.

You can have multiple --firstboot options. They run in the same order that they appear on the command line.

See also: "FIRSTBOOT" in virt-customize(1), --run.

--firstboot-command 'CMD+ARGS' (see "customize" below)

Run command (and arguments) inside the guest when the guest first boots up (as root, late in the boot process).

You can have multiple --firstboot options. They run in the same order that they appear on the command line.

See also: "FIRSTBOOT" in virt-customize(1), --run.

--firstboot-install PKG,PKG.. (see "customize" below)

Install the named packages (a comma-separated list). These are installed when the guest first boots using the guest’s package manager (eg. apt, yum, etc.) and the guest’s network connection.

For an overview on the different ways to install packages, see "INSTALLING PACKAGES" in virt-builder(1).

--hostname HOSTNAME (see "customize" below)

Set the hostname of the guest to "HOSTNAME". You can use a dotted hostname.domainname (FQDN) if you want.

--inject-blnsvr METHOD (see "customize" below)

Inject the Balloon Server (blnsvr.exe) into a Windows guest. This operation also injects a firstboot script so that the Balloon Server is installed when the guest boots.

The parameter is the same as used by the --inject-virtio-win operation.

Note that to do a full conversion of a Windows guest from a foreign hypervisor like VMware (which involves many other operations) you should use the virt-v2v(1) tool instead of this.

--inject-qemu-ga METHOD (see "customize" below)

Inject the QEMU Guest Agent into a Windows guest. The guest agent communicates with qemu through a socket in order to provide enhanced features (see qemu-ga(8)). This operation also injects a firstboot script so that the Guest Agent is installed when the guest boots.

The parameter is the same as used by the --inject-virtio-win operation.

Note that to do a full conversion of a Windows guest from a foreign hypervisor like VMware (which involves many other operations) you should use the virt-v2v(1) tool instead of this.

--inject-virtio-win METHOD (see "customize" below)

Inject virtio-win drivers into a Windows guest. These drivers add virtio accelerated drivers suitable when running on top of a hypervisor that supports virtio (such as qemu/KVM). The operation also adjusts the Windows Registry so that the drivers are installed when the guest boots.

The parameter can be one of:

ISO

The path to the ISO image containing the virtio-win drivers (eg. /usr/share/virtio-win/virtio-win.iso).

DIR

The directory containing the unpacked virtio-win drivers (eg. /usr/share/virtio-win).

Note that to do a full conversion of a Windows guest from a foreign hypervisor like VMware (which involves many other operations) you should use the virt-v2v(1) tool instead of this.

--install PKG,PKG.. (see "customize" below)

Install the named packages (a comma-separated list). These are installed during the image build using the guest’s package manager (eg. apt, yum, etc.) and the host’s network connection.

For an overview on the different ways to install packages, see "INSTALLING PACKAGES" in virt-builder(1).

See also --update, --uninstall.

--keep-user-accounts USERS (see "user-account" below)

The user accounts to be kept in the guest. The value of this option is a list of user names separated by comma, where specifying an user means it is going to be kept. For example:

 --keep-user-accounts mary

would keep the user account "mary".

This option can be specified multiple times.

--link TARGET:LINK[:LINK..] (see "customize" below)

Create symbolic link(s) in the guest, starting at "LINK" and pointing at "TARGET".

--mkdir DIR (see "customize" below)

Create a directory in the guest.

This uses "mkdir -p" so any intermediate directories are created, and it also works if the directory already exists.

--move SOURCE:DEST (see "customize" below)

Move files or directories inside the guest.

Wildcards cannot be used.

--no-logfile (see "customize" below)

Scrub "builder.log" (log file from build commands) from the image after building is complete. If you don't want to reveal precisely how the image was built, use this option.

See also: "LOG FILE".

--no-selinux-relabel (see "customize" below)

Do not attempt to correct the SELinux labels of files in the guest.

In such guests that support SELinux, customization automatically relabels files so that they have the correct SELinux label. (The relabeling is performed immediately, but if the operation fails, customization will instead touch /.autorelabel on the image to schedule a relabel operation for the next time the image boots.) This option disables the automatic relabeling.

The option is a no-op for guests that do not support SELinux.

--password USER:SELECTOR (see "customize" below)

Set the password for "USER". (Note this option does not create the user account).

See "USERS AND PASSWORDS" in virt-builder(1) for the format of the "SELECTOR" field, and also how to set up user accounts.

--password-crypto md5|sha256|sha512 (see "customize" below)

When the virt tools change or set a password in the guest, this option sets the password encryption of that password to "md5", "sha256" or "sha512".

"sha256" and "sha512" require glibc ≥ 2.7 (check crypt(3) inside the guest).

"md5" will work with relatively old Linux guests (eg. RHEL 3), but is not secure against modern attacks.

The default is "sha512" unless libguestfs detects an old guest that didn't have support for SHA-512, in which case it will use "md5". You can override libguestfs by specifying this option.

Note this does not change the default password encryption used by the guest when you create new user accounts inside the guest. If you want to do that, then you should use the --edit option to modify "/etc/sysconfig/authconfig" (Fedora, RHEL) or "/etc/pam.d/common-password" (Debian, Ubuntu).

--remove-user-accounts USERS (see "user-account" below)

The user accounts to be removed from the guest. The value of this option is a list of user names separated by comma, where specifying an user means it is going to be removed. For example:

 --remove-user-accounts bob,eve

would only remove the user accounts "bob" and "eve".

This option can be specified multiple times.

--root-password SELECTOR (see "customize" below)

Set the root password.

See "USERS AND PASSWORDS" in virt-builder(1) for the format of the "SELECTOR" field, and also how to set up user accounts.

Note: In virt-builder, if you don't set --root-password then the guest is given a random root password.

--run SCRIPT (see "customize" below)

Run the shell script (or any program) called "SCRIPT" on the disk image. The script runs virtualized inside a small appliance, chrooted into the guest filesystem.

The script is automatically chmod +x.

If libguestfs supports it then a limited network connection is available but it only allows outgoing network connections. You can also attach data disks (eg. ISO files) as another way to provide data (eg. software packages) to the script without needing a network connection (--attach). You can also upload data files (--upload).

You can have multiple --run options. They run in the same order that they appear on the command line.

See also: --firstboot, --attach, --upload.

--run-command 'CMD+ARGS' (see "customize" below)

Run the command and arguments on the disk image. The command runs virtualized inside a small appliance, chrooted into the guest filesystem.

If libguestfs supports it then a limited network connection is available but it only allows outgoing network connections. You can also attach data disks (eg. ISO files) as another way to provide data (eg. software packages) to the script without needing a network connection (--attach). You can also upload data files (--upload).

You can have multiple --run-command options. They run in the same order that they appear on the command line.

See also: --firstboot, --attach, --upload.

--script SCRIPT (see "script" below)

Run the named "SCRIPT" (a shell script or program) against the guest. The script can be any program on the host. The script’s current directory will be the guest’s root directory.

Note: If the script is not on the $PATH, then you must give the full absolute path to the script.

--scriptdir SCRIPTDIR (see "script" below)

The mount point (an empty directory on the host) used when the "script" operation is enabled and one or more scripts are specified using --script parameter(s).

Note: "SCRIPTDIR" must be an absolute path.

If --scriptdir is not specified then a temporary mountpoint will be created.

--scrub FILE (see "customize" below)

Scrub a file from the guest. This is like --delete except that:

•

It scrubs the data so a guest could not recover it.

•

It cannot delete directories, only regular files.

--selinux-relabel (see "customize" below)

This is a compatibility option that does nothing.

--ssh-inject USER[:SELECTOR] (see "customize" below)

Inject an ssh key so the given "USER" will be able to log in over ssh without supplying a password. The "USER" must exist already in the guest.

See "SSH KEYS" in virt-builder(1) for the format of the "SELECTOR" field.

You can have multiple --ssh-inject options, for different users and also for more keys for each user.

--tar-in TARFILE:REMOTEDIR (see "customize" below)

Copy local files or directories from a local tar file called "TARFILE" into the disk image, placing them in the directory "REMOTEDIR" (which must exist). Note that the tar file must be uncompressed (.tar.gz files will not work here)

--timezone TIMEZONE (see "customize" below)

Set the default timezone of the guest to "TIMEZONE". Use a location string like "Europe/London"

--touch FILE (see "customize" below)

This command performs a touch(1)-like operation on "FILE".

--truncate FILE (see "customize" below)

This command truncates "FILE" to a zero-length file. The file must exist already.

--truncate-recursive PATH (see "customize" below)

This command recursively truncates all files under "PATH" to zero-length.

--uninstall PKG,PKG.. (see "customize" below)

Uninstall the named packages (a comma-separated list). These are removed during the image build using the guest’s package manager (eg. apt, yum, etc.). Dependent packages may also need to be uninstalled to satisfy the request.

See also --install, --update.

--update (see "customize" below)

Do the equivalent of "yum update", "apt-get upgrade", or whatever command is required to update the packages already installed in the template to their latest versions.

See also --install, --uninstall.

--upload FILE:DEST (see "customize" below)

Upload local file "FILE" to destination "DEST" in the disk image. File owner and permissions from the original are preserved, so you should set them to what you want them to be in the disk image.

"DEST" could be the final filename. This can be used to rename the file on upload.

If "DEST" is a directory name (which must already exist in the guest) then the file is uploaded into that directory, and it keeps the same name as on the local filesystem.

See also: --mkdir, --delete, --scrub.

--write FILE:CONTENT (see "customize" below)

Write "CONTENT" to "FILE".

Operations

If the --enable/--operations option is not given, then most sysprep operations are enabled.

Use "virt-sysprep --list-operations" to list all operations for your virt-sysprep binary. The ones which are enabled by default are marked with a "*" character. Regardless of the --enable/--operations options, sysprep operations are skipped for some guest types.

Operations can be individually enabled using the --enable/--operations options. Use a comma-separated list, for example:

 virt-sysprep --operations ssh-hostkeys,udev-persistent-net [etc..]

Future versions of virt-sysprep may add more operations. If you are using virt-sysprep and want predictable behaviour, specify only the operations that you want to have enabled.

"*" = enabled by default when no --enable/--operations option is given.

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

Security

Virtual machines that employ full disk encryption internally to the guest should not be considered for cloning and distribution, as it provides multiple parties with the same internal volume key, enabling any one such party to decrypt all the other clones. Refer to the LUKS FAQ for details.

Although virt-sysprep removes some sensitive information from the guest, it does not pretend to remove all of it. You should examine the "OPERATIONS" above and the guest afterwards.

Sensitive files are simply removed. The data they contained may still exist on the disk, easily recovered with a hex editor or undelete tool. The --scrub option can be used to scrub files instead of just deleting them. virt-sparsify(1) is another way to remove this content. See also the scrub(1) command to get rid of deleted content in directory entries and inodes.

 cp template.img newguest.img
 virt-sysprep --enable customize -a newguest.img

Notes

Exit status

This program returns 0 on success, or 1 if there was an error.

Environment

"VIRT_TOOLS_DATA_DIR"

This can point to the directory containing data files used for Windows firstboot installation.

Normally you do not need to set this. If not set, a compiled-in default will be used (something like /usr/share/virt-tools).

This directory may contain the following files:

rhsrvany.exe

This is the RHSrvAny Windows binary, used to install a "firstboot" script in Windows guests. It is required if you intend to use the --firstboot or --firstboot-command options with Windows guests.

See also: "https://github.com/rwmjones/rhsrvany"

pvvxsvc.exe

This is a Windows binary shipped with SUSE VMDP, used to install a "firstboot" script in Windows guests. It is required if you intend to use the --firstboot or --firstboot-command options with Windows guests.

For other environment variables, see "ENVIRONMENT VARIABLES" in guestfs(3).