qq2clone/man.pandoc

% QQ2CLONE(1) qq2clone 0.1
% Jesse Gardner
% February 2021

# NAME
qq2clone - Create and manage QEMU/KVM VMs using template machines and qcow2
  images with backing files
  
# SYNOPSIS
**qq2clone** [*OPTION*]... *COMMAND* [*ARG*]...

# DESCRIPTION
**qq2clone** is a tool working on top of virsh that makes creating clones 
of template QEMU/KVM machines simple. By using the copy on write feature
for which qcow2 is named, clones of an existing virtual machine can be made
without inadvertently altering the original image (with caveats - read the 
**LIMITATIONS** section if you aren't already familiar with how copy on 
write works). **qq2clone** makes creating and managing these clones simple 
and efficient. 

**qq2clone** supports creating numerous clones of a template and 
performing batch operations on them - including the execution of arbitrary 
commands with exec. This simplifies workflows involving large numbers of 
virtual machines, or the frequent creation/destruction of virtual machines.

In addition to virsh, basic linux utilities and QEMU/KVM, qq2clone 
requires:

    Bash 4.0+
    qemu-img
    libvirt tools: 
        virt-clone
        virt-xml
    virt-xml-validate
    xmllint (from libxml2)

If you want to easily establish graphical connections to your virtual 
machines, you should have virt-viewer and/or spicy installed and configure 
your templates to use Spice graphics. This is not strictly necessary, and 
with the use of **qq2clone** **exec** and a small script of your own
you can automate connecting to Spice/VNC clients of your choice without 
too much hassle

# OPTIONS

Not every option has an effect in the context of every command. Specifying 
an option that has no effect in the context of the command being invoked 
will not produce an error, it simply will not do anything

Options are parsed left to right, and right-hand options override 
left-hand options. The only exception is for \-Q/\-\-quieter, which *must* 
be the first option listed to work properly.

\-c, \-\-connection  [*URI*] 
: Specify a non-default connection URI: sets the value of 
LIBVIRT_DEFAULT_URI

\-f, \-\-no\-spice
: Do not attempt to connect to a virtual machine's Spice graphics. 
Overrides USE_SPICE setting in configuration

\-g, \-\-use\-spice
: Attempt to connect to a virtual machine's spice graphics. Overrides 
SPICE setting in configuration

\-h, \-\-help
: Print basic help information and exit

\-n, \-\-no-run
: After making a clone of a template, do not run it. Overrides NORUN 
setting in configuration

\-q, \-\-quiet
: Suppress most non-error output. Overrides QUIET setting in 
configuration. Also suppresses various prompts for user choices, either 
exiting with an error or making a safe default choice depending on the 
command. Recommended only once familiar with the behavior of **qq2clone**

\-Q, \-\-quieter
: This option is (currently) required to appear immediately following the 
invocation of **qq2clone**. Suppresses all output, error message or 
otherwise, except when running interactive commands or 
commands that require output to be useful. The commands for which output 
is not entirely supressed are: config list, config info, list, 
list-templates, exec, edit, modify-template edit, and check. Other 
commands will receive only an exit code as output. This option is intended
for calling qq2clone from a script.

\-r, \-\-run
: Run a clone when creating it. Overrides NORUN setting in configuration

\-s, \-\-storage [*LOCATION*]
: When creating a clone, place new disk image file(s) at location 
specified by [*LOCATION*]. [*LOCATION*] may be one of an absolute 
filepath, or the name of a libvirt directory type storage pool. Also 
defines where state files will be saved when using **save** command. 
Overrides STORAGE option in configuration

\-S, \-\-spicy
: Use spicy rather than virt-viewer when connecting to the spice graphics 
of a clone. Overrides SPICY setting in configuration

\-t, \-\-template [*NAME*]
: Use template of given name as context when executing a clone command 
(see TYPES OF COMMAND section above). Overrides TEMPLATE option in 
configuration

\-v, \-\-verbose
: Enable all output. Overrides QUIET setting in configuration

\-V, \-\-virt\-viewer
: Use virt-viewer rather than spicy when connecting to the spice graphics 
of a clone. Overrides SPICY setting in configuration

# TYPES OF COMMAND

There are two main classes of commands: commands that operate directly on 
templates, and commands that create or operate on clones of templates. In 
order to make it less likely that the user may unintentionally invoke a 
command of one class when they intended to invoke one of the other, they 
use a different syntax. Commands that operate on templates use the syntax: 


**qq2clone** **command** [*template-name*] [*ARG*] ... 

while commands that operate on clones use the syntax: 

**qq2clone** \-\-template [*template-name*] **command** [*ARG*] ... 

Notice that commands operating on clones work within the context of a 
template defined by the option \-\-template/\-t. Conversely, commands 
operating on templates specify the template as an  argument to the 
command. There can also be a default template  defined by the 
TEMPLATE option in the configuration file, allowing the \-\-template 
option to be omitted for commands that operate on clones. Commands 
operating on templates do not respect this default - the template must 
always be explicitly defined, further reducing the likelihood of 
accidentally modifying or deleting a template.

# TEMPLATE COMMMANDS

**copy-template** [*CURRENT-NAME*] [*NEW-NAME*]
: Copy the XML of template *CURRENT-NAME* to a new template with 
*NEW-NAME*. The new template will not receive a copy of the old template's
storage devices - it will point to the same locations

**delete-template** [*NAME*]
: Delete the template *NAME*. This operation will succeed only if there 
are currently no clones of the template

**import-template** [*LIBVIRT-DOMAIN*] [*NAME*], **import-template** 
[*XML-LOCATION*] [*NAME*]
: Import a new template from either an existing libvirt domain, or a fully 
qualified filepath to a libvirt domain XML file on disk. If argument 
*NAME* is ommited, qq2clone will assume you want to use the machine's name 
as described in the XML file as the template name

**list-templates**
: List the names of all existing templates

**modify-template** [*NAME*] **sub-command** [*ARG*] ...
: Templates can be modified in various ways by invoking 
**modify-template**. Each subcommand is described below

**modify-template** [*NAME*] **commit-image**
: After an image has been created and modified as desired using 
**modify-template**  [*NAME*] **prepare-image**, **commit-image** is used 
to alter a template's underlying storage device by commiting any changes 
made using prepare-image. See the commit command described in **man** 
**qemu-img** for more information on how this works

**modify-template** [*NAME*] **destroy-image**
: Invoke virsh destroy on a running image created/run through 
**modify-template** [*NAME*] **prepare-image**. This is generally not 
wise, as it is equivalent to unplugging a physical machine and could cause 
corruption to the image that will later be commited as a permanent change 
to the template's image

**modify-template** [*NAME*] **discard-image**
: Delete an image produced by **modify-template** [*NAME*] 
**prepare-image** without commiting any changes

**modify-template** [*NAME*] **edit**
: Edit the XML document defining a template

**modify-template** [*NAME*] **rename** [*NEW-NAME*]
: Change the name of a template, and all of its clones

**modify-template** [*NAME*] **prepare-image**
: Create and/or run a clone  that acts as a staging area for changes to 
the `template's` actual image. For instance, you could update the 
`template's` software by running **modify-template** [*NAME*] 
**prepare-image**, updating the clone produced by this command,
shutting it down, and then running **modify-template** [*NAME*] 
**commit-image**. This serves a twofold purpose - to prevent incidental 
damage to an underlying image by providing a safe buffer to work in, and 
to allow modifications to be safely prepared for an underlying image even 
while that image has existing clones.

# CLONE COMMANDS

A description of the argument *SET* is described in the **SETS** section 
below

**clone** [*NUMBER*]
: Invoke without any argument to produce a single clone. Supply a number 
as an argument to specify the number of clones to create

**connect** [*SET*]
: Start any machine in *SET* that `isn't` already running. If any machine 
in *SET* has spice graphics and spicy or virt-viewer is installed, use one 
or the other (chosen by command-line option or configuration) to connect 
to the graphical console

**destroy** [*SET*]
: Invoke virsh destroy on any running machine in *SET* (in other words, if 
the domain is running forcibly turn it off)

**edit** [*NUMBER*]
: Edit the XML file of the clone with given number

**exec** [*SET*] [*command-string*]
: For every machine in *SET*, sequentially, execute the contents of the 
command string in an environment where the following variables are defined 
per clone: `"$uuid"`, `"$name"`, `"$disks"` (a newline delimited string 
containing the machine's qcow2 disk device filepaths). This is done using 
bash's eval command, so be sure to put any instances of these variables in 
single quotes (double quotes inside the single quotes is best practice) or 
they will not be set properly. If any instance of exec has a non-zero 
return value, execution stops.

**list** [*ARG*]
: Without arguments, list all clones of the current template and their 
state. With argument "all", provide list including all clones of every 
template. With argument "xml", produce an XML document with information 
about every template, their clones, and their state. The XML option 
is not complete - its format is at this point defined only implicitly, by 
the output of this command.

**resume** [*SET*]
: Resume any suspended machines in *SET*

**rm** [*SET*]
: Destroy every domain in *SET* (if running), undefine them and delete 
their storage volumes

**rm-wipe** [*SET*]
: Destroy every domain in *SET* (if running), undefine them and wipe their 
storage volumes using virsh

**rm-shred** [*SET*]
: Destroy every domain in *SET* (if running), undefine them and shred 
their storage volumes

**save** [*SET*]
: Save execution state of every running domain in *SET* to file

**save-rm** [*SET*]
: Delete the state file associated with every machine in *SET*

**start** [*SET*]
: Start every machine in *SET* that is currently not running. For saved 
domains, their state will be restored

**suspend** [*SET*]
: Suspend execution of every machine in *SET*

# OTHER COMMANDS

**check** [*TEMPLATE-NAME*]
: As described in the limitations section, there are ways that qq2clone 
can lose track of a clone. If this happens, it will remain in qq2clone's 
database, its ID number will remain reserved, and its image files may not 
be deleted and take up space doing nothing. the **check** command tries to 
find and fix this and other problems. The *TEMPLATE-NAME* argument is 
optional, and restricts the check to that template and its clones. 
Otherwise, all templates are checked

**config** list, **config** info [*OPTION*], **config** edit [*OPTION*]
: List all configuration options and their current value, get info about a 
particular option, or edit one

# SETS	

*SET* is listed as an argument to many commands. *SET* simply describes a 
set of virtual machines - clones of a given template. *SET* is a comma 
delimited list with no whitespace. *SET* can be an individual machine or 
several individual machines designated by number:

    1                 (Machine 1)
    3,7               (Machines 3 and 7)

Machine numbers can be shown with **qq2clone** **list**. Ranges and 
omitted values are supported as well:

    1,2-5,^3          (Machines 1 and 2-5 excluding 3)
    1-10,^3-7         (Machines 1-10 excluding 3-7)

Lastly, groups of machines can be addressed by their state:

    all               (All machines)
    all,^running      (All machines that aren't running)
    ^running,1-10     (Machines 1-10 except those that are running)

The possible states of a virtual machine are based on the states listed in 
**man virsh**, with some modifications. States in qq2clone are: 

    all
    crashed
    idle
    in-shutdown
    off
    paused
    pmsuspended
    running
    saved

Specifying machines that do not exist will not cause an error: i.e., 
1-10 is a valid set even if only machines 3-7 exist. A set will only cause 
an error if it is malformed, includes zero existing machines, contains no 
machines that the command being invoked may act upon, or includes numbers 
less than 1.

# CONFIG

There is no need to refer to the manual to understand configuration 
options. Use "**qq2clone** config list" to see all options and their 
current values, and "**qq2clone** config info [*OPTION*]" to get 
information about a particular option. However, here is the same 
information provided by **qq2clone** info for each option

TEMPLATE

> This template will be used for commands like clone, rm, destroy when 
option \-\-template/\-t is not specified
>
> Default value: Default value: `'0'`

TEMPLATE_DIR

> This is the where template XML files will be kept
>
> Default value: `'${HOME}/storage-qq2clone/templates'`

QUIET

> If set to 1, most non-error output will be suppressed
>
> Default value: `'0'`

USE_SPICE

> If set to 1, attempt to connect 
> to the spice graphics of a virtual machine by default when cloning it, 
if it is configured to use spice graphics. qq2clone can do this using the 
programs spicy and virt-viewer. If either is installed on your system 
during the first run, the default value is `'1'` (enabled). Otherwise, the 
default value is `'0'`

S_TIMEOUT

> Wait this many seconds before timing out when trying to connect to a 
virtual `machine's` spice graphics.
>
> Default value: `'10'`

STORAGE

> The default location to store clone images when creating them. Changing 
this location is fine, but it is a good idea to ensure that whatever 
location you do choose is only used by qq2clone
>
> Default value: `'${HOME}/storage-qq2clone/qq2clone-pool'`

# EXAMPLES

**qq2clone** \-\-template Debian \-\-run \-\-virt-viewer clone
: Make a clone of Debian, run it, and connect to its spice graphics using 
virt\-viewer. All of these options could have instead been defined in the 
configuration, so that the entire command would be: **qq2clone** clone

**qq2clone** \-\-template Debian exec 3 'virsh console "$uuid"'
: Use virsh to connect to the serial console of template Debian's clone 
with number 3 (as shown in **qq2clone** list)

**qq2clone** **modify-template** Debian *prepare-image*
: Create a clone of Debian that can be used as a staging area for 
permanent changes to the backing template storage device

**qq2clone** **modify-template** Debian **commit-image**
: Commit changes to the image Debian staged with the previous command

**qq2clone** **copy-template** Debian Debian_2
: Copy the XML of template Debian, creating a new template with the same 
backing storage device that you can edit as you please

# LIMITATIONS

The largest limitation of **qq2clone** is that it cannot protect your 
template images from the actions of other software. If nothing else 
touches a template's storage volumes, qq2clone can safely handle them 
(barring unknown bugs or bad luck during a commit-image). However, 
if something else alters the image upon which a template is based, its 
existing clones may be corrupted and future clones may behave differently 
than expected. It is the user's responsibility to understand this aspect 
of copy on write and carefully manage template images. Future updates to 
qq2clone may add features that give some additional protections, but this 
risk is inherent to copy on write.

Libvirt has permissions errors when a storage pool is in a "hidden" 
directory with a name beginning with "." and qcow2 files with backing files 
are involved. This may be due to apparmor, or it may be an issue with 
libvirt. It is unknown how widespread this issue is, but it is the reason
that the default directory storage-qq2clone does not start with '.'

If the UUID of a clone is changed, qq2clone will no longer be able to 
track it and will not be able to perform commands on it anymore. 
If virsh undefine is run on a clone, qq2clone will not be able to see 
it once it is turned off. This limitation will be eliminated or reduced in 
the future, when qq2clone moves away from relying on virsh and implements 
direct usage of the libvirt API. It could be addressed now by using 
transient domains, but that would require qq2clone to do more things 
manually instead of just invoking virsh. Since the plan is to 
transition to a different approach later, that would be wasted effort. For 
now, if you find yourself in this position just use **qq2clone** check.

qq2clone can only produce clones by making qcow2 image files. The backing 
file need not be qcow2, but the images produced by qq2clone always will 
be. This is unlikely to ever change - levaraging the features of qcow2 is 
the entire purpose of qq2clone. If it does change, qq2clone will need a 
new name.

qq2clone does not support creating images in pool types other than 
directories, and attempting to use a machine as a template when it has 
storage volumes in a non-directory pool is likely to fail or have 
unexpected results. Support for some other pool types may be added in the 
future.

qq2clone currently cannot copy storage volumes when importing a template 
(it just references the originals), or when copying a template. This will 
change in the future, and qq2clone will also be able to handle more complex
relationships between templates, clones and their images

# FILES

~/.config/qq2clone

: This document simply contains a string defining the location at which
qq2clone will store files, including the database containing the rest of
it configuration options. Currently, qq2clone cannot run without ${HOME}
being defined unless a few lines are altered to refer to a new location

~/storage-qq2clone

: Directory where qq2clone stores all files and binary executables. Can be 
changed by modifying ~/.config/qq2clone. This directory is not 
named "qq2clone" because it can then slightly interfere with bash 
completion when in the home directory, and it does not start with a '.' 
for the reasons described in the **LIMITATIONS** section above

~/storage-qq2clone/qq2clone.db
: sqlite3 database containing the configuration information for qq2clone, 
as well as data about templates and clones

~/storage-qq2clone/qq2clone-pool

: Storage pool used for clone images and saved state files, if the 
\-\-storage option is not used when creating or saving a clone and the 
option STORAGE is not changed in the configuration file

~/qq2clone/templates

: Directory in which template XML files are stored. These can be edited 
manually, but it is more advisable to use **qq2clone** **modify-template** 
[*template-name*] edit

# BUGS

As described in the options section, the implementation of the 
\-\-quieter/\-Q option needs some work. Its current behavior is the 
easiest functional approach without complicating the options parser, but it 
will eventually be modified and become better behaved. In addition to the 
previously described problem, very early error messages will not be 
suppressed. Most likely, the solution is to implement a better options 
parser and make it the first thing to run when executing qq2clone. However,
the impact of this bug is minimal and other improvements are likely to 
come before this bug fix.

If you find any worse bugs, and I'm sure I missed some, please let me know 
and I will fix them as time allows.

# EXIT VALUES

**10**	
: No permission to access file or file doesn't exist

**11**
: Required software dependencies are not met (see description for a list), 
or are cannot be found in PATH

**12**
: Invalid command line argument specified, or command specifies an invalid 
action

**13**
: Problem with a template - i.e., specified template does not exist, or 
import-template failed because template of specified name already exists

**14**
: Invocation of an external command failed

**15**
: Problem with a libvirt XML file

**16**
: Attempted action with a libvirt tool resulted in failure

**17**
: Could not establish graphical spice connection to machine before timeout 
expired

**18**
: A file is of the wrong type or does not exist

**19**
: Unexpected error - a bug in qq2clone, or a highly unexpected failure of 
some command