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Create virtual machines quickly with virt-builder

Project description

virt-up

virt-up is a command line tool for creating virtual machines quickly on a local KVM hypervisor using virt-builder, virt-sysprep, and virt-install.

Virtual machines are created from existing digitally signed OS images, which are downloaded and cached. A template virtual machine is created from the downloaded image. Optionally, an ansible playbook is executed to further customize the templates. Virtual machines are then cloned from the templates to quickly create new instances.

A login user and the ssh keys to connect to the new virtual machines are created automatically. The login user is given sudo access. Connection information is stored in a json meta data file for each virtual machine created. An ansible inventory file is created for the templates and instances to make it easier to run ansible playbooks for further configuration.

Normally you should run virt-up as a regular user, not root.

By default, virt-up will create image files in the default libvirt storage pool (/var/lib/libvirt/images). See the pool option Settings to change this. Be sure you have read and write access to the configured libvirt storage pool.

System requirements

  • Python 3.6 or better
  • Local KVM hypervisor
  • Python libvirt package
  • libosinfo, qemu-img, virt-builder, virt-sysprep, virt-install

Usage

usage: virt-up [--name] <name> --template <template> [create-options]
       virt-up [--name] <name> --login [--sftp|--command "<command>"]
       virt-up [--name] <name> --playbook <playbook>
       virt-up [--name] <name> --delete | --delete --all
       virt-up --init [--force]
       virt-up --list [--all]
       virt-up --show-templates | --show-paths

positional arguments:
  <name>                instance name

optional arguments:
  -h, --help            show this help message and exit
  --version             show program's version number and exit
  --init                initialize configuration files
  --list                list instances
  --show-templates      show template definitions
  --show-paths          show configuration and data paths
  --delete              delete the instance
  --login               login to a running instance
  --playbook PLAYBOOK   run ansible playbook on instance
  -t <template>, --template <template>
                        template name (default: <name>)
  --root-password <root-password>
                        root password (default: random)
  --user <user>         username (default: virt)
  --password <password>
                        password (default: random)
  --size <size>         instance disk size (default: image size)
  --memory <memory>     instance memory (default: 512)
  --vcpus <vcpus>       instance vcpus (default: 1)
  --graphics <graphics>
                        instance graphics type (default: none)
  --dns-domain <dns-domain>
                        dns domain name
  --sftp                --login with sftp
  --command <command>   --login ssh command
  --no-clone            build template instance only
  --no-inventory        exclude instance from the virt-up ansible inventory
                        file
  --all                 include template instances
  --yes                 answer yes to interactive questions
  --quiet               show less output
  --debug               show debug tracing
  --force               overwrite files

Configuration files

virt-up reads settings from INI formatted configuration files. The settings are divided into common settings and template definitions.

System defined configurations are located in the directory ‘/etc/virt-up’.

User defined configurations are located via a path set by an environment variable (see _virt_config_ below).

Common Settings

The settings.cfg file contains settings that are used when creating any virtual machine. The file should contain one section called [common].

The following fields are supported:

pool
The libvirt storage pool to write images. (default: default)
username
The username of the user account created by virt-up when creating new template instances (default: virt)
memory
Instance memory, in KB. Default is 512.
vcpus
Number of virtual cpus. Default is 1.
graphics
Graphics type. Default is 1.
dns-domain
The DNS domain used for new template instance hostnames. (default: None)
address-source
The method used to detect the instance IP address. Supported values are:
  • agent - Queries the qemu guest agent to obtain the IP address (default)
  • lease - Parses the DHCP lease file to obtain the IP address (requires a libvirt managed DHCP server in the hypvervisor host)
  • arp - Examines the arp table on the hypvervisor host
  • dns - Uses the result of a DNS lookup for the guest host name.
image-format
The image format. Supported values are qcow2, and raw. (default: qcow2)
virt-builder-args
Extra arguments for virt-builder. (default: None)
virt-sysprep-args
Extra arguments for virt-sysprep. (default: None)
virt-install-args
Extra arguments for virt-install. (default: None)
template-playbook
Optional ansible playbook to be executed on newly created template instances. (default: None)
instance-playbook
Optional ansible playbook to be executed on newly created instances. (default: None)

These fields can be overridden by individual template definitions.

Template definitions

Template definitions are read from the files located in the templates.d sub-directory.

Provide one section for each template definition. The section name is the name for the template definition and is used for the virt-up --template option. The following fields are supported:

desc
A text description, show by --list-templates.
os-version
The virt-builder <os_version> name. See virt-builder --list for available names.
os-type
The virt-install --os-type
os-variant
The virt-install --os-variant. See osquery-info os for available names.
arch
The target architecture.
memory
Instance memory, in KB. Default is set in the common section.
vcpus
Number of virtual cpus. Default is set in the common section.
graphics
Graphics type. Default is set in the common section.
virt-builder-args
Template specific extra arguments for virt-builder. (default: None)
virt-sysprep-args
Template specific extra arguments for virt-sysprep. (default: None)
virt-install-args
Template specific extra arguments for virt-install. (default: None)
template-playbook
Optional ansible playbook to be executed on newly created template instances. (default: None)
instance-playbook
Optional ansible playbook to be executed on newly created instances. (default: None)

In addition, the template configuration can override fields set in the common section of the settings.cfg file.

Additional Notes

General notes

  • If the hypvervisor host uses a bridged network or a seperate network adapter for guest systems, the host’s arp table may not contain the ip address of the guest.
  • Values set in the template configuration sections will override the common settings

OS Info database

Operating system specific information is provided by the OS Info Database (osinfo-db) library. The OS Info Database provided by your package manager may be out of date and not provide definitions for recent operating system versions.

If you have already updated your system, and the osinfo-db is still to old, then you can use the osinfo-db-import tool with the --local option to install an up-to-date database in your home directory which will not conflict with your package manager installation. The osinfo-db-import tool is provided by the package name osinfo-db-tools on yum and apt managed systems.

See https://libosinfo.org/download for more information.

Ubuntu installation notes

Linux images are not readable by regular users on recent Ubuntu distributions, which breaks the ability of libguestfs to modify guest images. Update the permissions with the dpkg-statoverride command to be able to run the libguestfs tools as a regular user:

$ for image in /boot/vmlinu*; do sudo dpkg-statoverride –update –add root root 0644 $image || true; done

You will need to run this everytime the kernel is updated.

Xen

virt-up can create and manage guests using the Xen hypervisor.

  • To use a Xen hypervisor, set the LIBVIRT_DEFAULT_URI to use the xen system

    LIBVIRT_DEFAULT_URI=xen:///system

    and set virt-install-args to include ‘–hvm’.

    virt-install-args = ‘–hvm …’

  • Xen does not support accessing guest information via the qemu-agent

  • Some guest images are built with Xen support, but their device configurations are unloaded during initial boot processinmg. A boot parameter xen_emul_unplug=never must be added to the guest boot cmdline. This is usually done by updating the grub configuration when building the template.

    virt-builder-args = …

    –edit “/etc/default/grub:s/GRUB_CMDLINE_LINUX=""/GRUB_CMDLINE_LINUX="xen_emul_unplug=never"/” –run-command ‘grub-mkconfig -o /boot/grub/grub.cfg’ …

Environment Variables

The following environment variables are used by virt-up

LIBVIRT_DEFAULT_URI
URI to access libvirt. Defaults to qemu://session

virt_config

VIRTUP_CONFIG_HOME
Path to virt-up configuration files. Defaults to $XDG_CONFIG_HOME/virt-up
XDG_CONFIG_HOME
Path to virt-up configuration files. Defaults to the xdg standard location
$HOME/.local/share/virt-up

virt_data

VIRTUP_DATA_HOME
Path to virt-up run-data files created by virt-up. Defaults to $XDG_DATA_HOME/virt-up
XDG_DATA_HOME
Path to virt-up run-data files created by virt-up. Defaults to the xdg standard location $HOME/.local/share/virt-up

FILES

The following files are created or referenced by virt-up

Runtime persistent data files

  • virtup_data/sshkeys/``name``
  • virtup_data/macaddrs.json
  • virtup_data/instance/``name``.json
  • virtup_data/inventory.yaml

Guest system image files

  • pool/TEMPLATE-template disk images
  • pool/virtual guest disk images

Transient runtime

  • /var/run/user/uid/virt-up.lock If the above directory is not available
  • /tmp/virt-up.lock

See Also

virt-builder virt-install virt-sysprep libvirt

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