Vagrant Libvirt Provider

This is a Vagrant plugin that adds an Libvirt provider to Vagrant, allowing Vagrant to control and provision machines via Libvirt toolkit.

Note: Actual version is still a development one. Feedback is welcome and can help a lot :-)

Features

Control local Libvirt hypervisors.
Vagrant up, destroy, suspend, resume, halt, ssh, reload and provision commands.
Upload box image (qcow2 format) to Libvirt storage pool.
Create volume as COW diff image for domains.
Create private networks.
Create and boot Libvirt domains.
SSH into domains.
Setup hostname and network interfaces.
Provision domains with any built-in Vagrant provisioner.
Synced folder support via rsync, nfs or 9p.
Snapshots via sahara.
Package caching via vagrant-cachier.
Use boxes from other Vagrant providers via vagrant-mutate.

Future work

Take a look at open issues.

Installation

First, you should have libvirt installed if you plan to run VMs on your local system. For instructions, refer to your linux distribution's documentation,

Next, you must have Vagrant installed. Vagrant-libvirt supports Vagrant 1.5 and 1.6.

Now you're ready to install vagrant-libvirt using standard Vagrant plugin installation methods.

$ vagrant plugin install vagrant-libvirt

Possible problems with plugin installation on Linux

In case of problems with building nokogiri and ruby-libvirt gem, install missing development libraries for libxslt, libxml2 and libvirt.

In Ubuntu, Debian, ...

$ sudo apt-get install libxslt-dev libxml2-dev libvirt-dev

In RedHat, Centos, Fedora, ...

# yum install libxslt-devel libxml2-devel libvirt-devel

Vagrant Project Preparation

Add Box

After installing the plugin (instructions above), the quickest way to get started is to add Libvirt box and specify all the details manually within a config.vm.provider block. So first, add Libvirt box using any name you want. This is just an example of Libvirt CentOS 6.4 box available:

$ vagrant box add centos64 http://kwok.cz/centos64.box

Create Vagrantfile

And then make a Vagrantfile that looks like the following, filling in your information where necessary. In example below, VM named test_vm is created from centos64 box.

Vagrant.configure("2") do |config|
  config.vm.define :test_vm do |test_vm|
    test_vm.vm.box = "centos64"
  end
end

Start VM

In prepared project directory, run following command:

$ vagrant up --provider=libvirt

Vagrant needs to know that we want to use Libvirt and not default VirtualBox. That's why there is --provider=libvirt option specified. Other way to tell Vagrant to use Libvirt provider is to setup environment variable export VAGRANT_DEFAULT_PROVIDER=libvirt.

How Project Is Created

Vagrant goes through steps below when creating new project:

Connect to Libvirt localy or remotely via SSH.
Check if box image is available in Libvirt storage pool. If not, upload it to remote Libvirt storage pool as new volume.
Create COW diff image of base box image for new Libvirt domain.
Create and start new domain on Libvirt host.
Check for DHCP lease from dnsmasq server.
Wait till SSH is available.
Sync folders and run Vagrant provisioner on new domain if setup in Vagrantfile.

Libvirt Configuration

Provider Options

Although it should work without any configuration for most people, this provider exposes quite a few provider-specific configuration options. The following options allow you to configure how vagrant-libvirt connects to libvirt, and are used to generate the libvirt connection URI:

driver - A hypervisor name to access. For now only kvm and qemu are supported.
host - The name of the server, where libvirtd is running.
connect_via_ssh - If use ssh tunnel to connect to Libvirt.
username - Username and password to access Libvirt.
password - Password to access Libvirt.
id_ssh_key_file - The id ssh key file name to access Libvirt (eg: id_dsa or id_rsa or ... in the user .ssh directory)
socket - Path to the libvirt unix socket (eg: /var/run/libvirt/libvirt-sock)
uri - For advanced usage. Directly specifies what libvirt connection URI vagrant-libvirt should use. Overrides all other connection configuration options.

Connection-independent options:

storage_pool_name - Libvirt storage pool name, where box image and instance snapshots will be stored.

Here is an example of how to set these options.

Vagrant.configure("2") do |config|
  config.vm.provider :libvirt do |libvirt|
    libvirt.host = "example.com"
  end
end

Domain Specific Options

disk_bus - The type of disk device to emulate. Defaults to virtio if not set. Possible values are documented in libvirt's description for target.
nic_model_type - parameter specifies the model of the network adapter when you create a domain value by default virtio KVM believe possible values, see the documentation for libvirt
memory - Amount of memory in MBytes. Defaults to 512 if not set.
cpus - Number of virtual cpus. Defaults to 1 if not set.
nested - Enable nested virtualization. Default is false.
cpu_mode - What cpu mode to use for nested virtualization. Defaults to 'host-model' if not set.
volume_cache - Controls the cache mechanism. Possible values are "default", "none", "writethrough", "writeback", "directsync" and "unsafe". See driver->cache in libvirt documentation.
kernel - To launch the guest with a kernel residing on host filesystems. Equivalent to qemu -kernel.
initrd - To specify the initramfs/initrd to use for the guest. Equivalent to qemu -initrd.
random_hostname - To create a domain name with extra information on the end to prevent hostname conflicts.
cmd_line - Arguments passed on to the guest kernel initramfs or initrd to use. Equivalent to qemu -append.
graphics_type - Sets the protocol used to expose the guest display. Defaults to vnc. Possible values are "sdl", "curses", "none", "gtk", or "vnc".
graphics_port - Sets the port for the display protocol to bind to. Defaults to 5900.
graphics_ip - Sets the IP for the display protocol to bind to. Defaults to "127.0.0.0.1".
graphics_passwd - Sets the password for the display protocol. Working for vnc and spice. by default working without passsword.
video_type - Sets the graphics card type exposed to the guest. Defaults to "cirrus". Possible values are "cirrus", "std", "vmware", "qxl", "tcx", "cg3", or "none".
video_vram - Used by some graphics card types to vary the amount of RAM dedicated to video. Defaults to 9216.

Specific domain settings can be set for each domain separately in multi-VM environment. Example below shows a part of Vagrantfile, where specific options are set for dbserver domain.

Vagrant.configure("2") do |config|
  config.vm.define :dbserver do |dbserver|
    dbserver.vm.box = "centos64"
    dbserver.vm.provider :libvirt do |domain|
      domain.memory = 2048
      domain.cpus = 2
      domain.nested = true
      domain.volume_cache = 'none'
    end
  end

  # ...

Networks

Networking features in the form of config.vm.network support private networks concept.

Public Network interfaces are currently implemented using the macvtap driver. The macvtap driver is only available with the Linux Kernel version >= 2.6.24. See the following libvirt documentation for the details of the macvtap usage.

http://www.libvirt.org/formatdomain.html#elementsNICSDirect

An examples of network interface definitions:

  # Private network
  config.vm.define :test_vm1 do |test_vm1|
    test_vm1.vm.network :private_network, :ip => "10.20.30.40"
  end

  # Public Network
  config.vm.define :test_vm1 do |test_vm1|
    test_vm1.vm.network :public_network, :dev => "eth0", :mode => 'bridge'
  end

In example below, one network interface is configured for VM test_vm1. After you run vagrant up, VM will be accessible on IP address 10.20.30.40. So if you install a web server via provisioner, you will be able to access your testing server on http://10.20.30.40 URL. But beware that this address is private to libvirt host only. It's not visible outside of the hypervisor box.

If network 10.20.30.0/24 doesn't exist, provider will create it. By default created networks are NATed to outside world, so your VM will be able to connect to the internet (if hypervisor can). And by default, DHCP is offering addresses on newly created networks.

The second interface is created and bridged into the physical device 'eth0'. This mechanism uses the macvtap Kernel driver and therefore does not require an existing bridge device. This configuration assumes that DHCP and DNS services are being provided by the public network. This public interface should be reachable by anyone with access to the public network.

Private Network Options

Note: These options are not applicable to public network interfaces.

There is a way to pass specific options for libvirt provider when using config.vm.network to configure new network interface. Each parameter name starts with 'libvirt__' string. Here is a list of those options:

:libvirt__network_name - Name of libvirt network to connect to. By default, network 'default' is used.
:libvirt__netmask - Used only together with :ip option. Default is '255.255.255.0'.
:libvirt__dhcp_enabled - If DHCP will offer addresses, or not. Used only when creating new network. Default is true.
:libvirt__adapter - Number specifiyng sequence number of interface.
:libvirt__forward_mode - Specify one of none, nat or route options. This option is used only when creating new network. Mode none will create isolated network without NATing or routing outside. You will want to use NATed forwarding typically to reach networks outside of hypervisor. Routed forwarding is typically useful to reach other networks within hypervisor. By default, option nat is used.
:libvirt__forward_device - Name of interface/device, where network should be forwarded (NATed or routed). Used only when creating new network. By default, all physical interfaces are used.
:mac - MAC address for the interface.
model_type - parameter specifies the model of the network adapter when you create a domain value by default virtio KVM believe possible values, see the documentation for libvirt

Public Network Options

:dev - Physical device that the public interface should use. Default is 'eth0'.
:mode - The mode in which the public interface should operate in. Supported modes are available from the libvirt documentation. Default mode is 'bridge'.
:mac - MAC address for the interface.

Management Network

Vagrant-libvirt uses a private network to perform some management operations on VMs. All VMs will have an interface connected to this network and an IP address dynamically assigned by libvirt. This is in addition to any networks you configure. The name and address used by this network are configurable at the provider level.

management_network_name - Name of libvirt network to which all VMs will be connected. If not specified the default is 'vagrant-libvirt'.
management_network_address - Address of network to which all VMs will be connected. Must include the address and subnet mask. If not specified the default is '192.168.121.0/24'.

You may wonder how vagrant-libvirt knows the IP address a VM received. Libvirt doesn't provide a standard way to find out the IP address of a running domain. But we do know the MAC address of the virtual machine's interface on the management network. Libvirt is closely connected with dnsmasq, which acts as a DHCP server. dnsmasq writes lease information in the /var/lib/libvirt/dnsmasq directory. Vagrant-libvirt looks for the MAC address in this file and extracts the corresponding IP address.

Additional Disks

You can create and attach additional disks to a VM via libvirt.storage :file. It has a number of options:

path - Location of the disk image. If unspecified, a path is automtically chosen in the same storage pool as the VMs primary disk.
device - Name of the device node the disk image will have in the VM, e.g. vdb. If unspecified, the next available device is chosen.
size - Size of the disk image. If unspecified, defaults to 10G.
type - Type of disk image to create. Defaults to qcow2.
bus - Type of bus to connect device to. Defaults to virtio.
cache - Cache mode to use, e.g. none, writeback, writethrough (see the libvirt documentation for possible values or here for a fuller explanation). Defaults to default.

The following example creates two additional disks.

Vagrant.configure("2") do |config|
  config.vm.provider :libvirt do |libvirt|
    libvirt.storage :file, :size => '20G'
    libvirt.storage :file, :size => '40G', :type => 'raw'
  end
end

SSH Access To VM

vagrant-libvirt supports vagrant's standard ssh settings.

Forwarded Ports

vagrant-libvirt supports Forwarded Ports via ssh port forwarding. For each forwarded_port directive you specify in your Vagrantfile, vagrant-libvirt will maintain an active ssh process for the lifetime of the VM.

vagrant-libvirt supports an additional forwarded_port option gateway_ports which defaults to false, but can be set to true if you want the forwarded port to be accessible from outside the Vagrant host. In this case you should also set the host_ip option to '*' since it defaults to 'localhost'.

Synced Folders

vagrant-libvirt supports bidirectional synced folders via nfs or 9p and unidirectional via rsync. The default is nfs. Vagrant automatically syncs the project folder on the host to /vagrant in the guest. You can also configure additional synced folders.

You can change the synced folder type for /vagrant by explicity configuring it an setting the type, e.g.

config.vm.synced_folder './', '/vagrant', type: 'rsync'

Customized Graphics

vagrant-libvirt supports customizing the display and video settings of the managed guest. This is probably most useful for VNC-type displays with multiple guests. It lets you specify the exact port for each guest to use deterministically.

Here is an example of using custom display options:

Vagrant.configure("2") do |config|
  config.vm.provider :libvirt do |libvirt|
    libvirt.graphics_port = 5901
    libvirt.graphics_ip = '0.0.0.0'
    libvirt.video_type = 'qxl'
  end
end

Box Format

You can view an example box in the example_box/directory. That directory also contains instructions on how to build a box.

The box is a tarball containing:

qcow2 image file named box.img.
metadata.json file describing box image (provider, virtual_size, format).
Vagrantfile that does default settings for the provider-specific configuration for this provider.

Development

To work on the vagrant-libvirt plugin, clone this repository out, and use Bundler to get the dependencies:

$ git clone https://github.com/pradels/vagrant-libvirt.git
$ cd vagrant-libvirt
$ bundle install

Once you have the dependencies, verify the unit tests pass with rake:

$ bundle exec rake

If those pass, you're ready to start developing the plugin. You can test the plugin without installing it into your Vagrant environment by just creating a Vagrantfile in the top level of this directory (it is gitignored) that uses it. Don't forget to add following line at the beginning of your Vagrantfile while in development mode:

Vagrant.require_plugin "vagrant-libvirt"

Now you can use bundler to execute Vagrant:

$ bundle exec vagrant up --provider=libvirt

IMPORTANT NOTE: bundle is crucial. You need to use bundled vagrant.

Contributing

Fork it.
Create your feature branch (git checkout -b my-new-feature).
Commit your changes (git commit -am 'Add some feature').
Push to the branch (git push origin my-new-feature).
Create new Pull Request.

supercow/vagrant-libvirt