vagrant libvirt provider

Stepping stones for getting Vagrant working on libvirt

Vagrant remains one of my favorite ways of getting a virtual machine going. I use it on libvirt based systems, so I need vagrant libvirt install. There are a few caveats in installing that plugin, so I thought of documenting it here.

The first – and a bit unrelated – thing you may need to worry about when getting vms deployed is nesting. I will not get into details here, but these links can show you how:

• KVM-based Nested Virtualization
• Enable the setting for Nested KVM
• Nested Virtualization in KVM on CentOS/RHEL

Even though Vagrant installation is possible via yum / apt, I have found that most distros lag on the chosen version. Furthermore, I noticed that installing the vagrant-libvirt plugin on versions 2.2.4 or older is a bit of a recipe for disaster. My advice is to download and install Vagrant 2.2.5 or newer, as shown below.

On Centos / RHEL Host

These commands worked fine when I used versions 7 or 8. Note that Centos/RHEL 8 uses dnf instead of yum, but yum is available as a symbolic link, so you should not have to worry about it.

# basics
sudo yum install -y qemu-kvm wget

# make sure you have these installed before attempting to install
# the vagrant-libvirt  plugin
sudo yum install -y libvirt libvirt-devel ruby-devel gcc make

VER=2.2.6  ; # make sure to use a vagrant newer than 2.2.5
wget https://releases.hashicorp.com/vagrant/${VER}/vagrant_${VER}_x86_64.rpm
sudo rpm -Uvh vagrant_${VER}_x86_64.rpm

On Debian / Ubuntu Host

sudo apt update
sudo apt install -y qemu-kvm wget ; # basics
sudo apt install -y libvirt-bin libvirt-dev firewalld build-essential

VER=2.2.6  ; # make sure to use a vagrant newer than 2.2.5
wget https://releases.hashicorp.com/vagrant/${VER}/vagrant_${VER}_x86_64.deb
sudo dpkg -i ./vagrant_2.2.6_x86_64.deb

at last…

vagrant plugin install vagrant-libvirt

Vagrant boxes

At this point, you should be able to tap into the vast world of vagrant boxes available to libvirt providers. Stay safe and stick with official or boxes you are familiar with. Something like centos/8 or debian/jessie64 are popular choices.

Bonus material: sshfs

A convenient way of getting files shared between host and vm is by using sshfs mount. The vagrant sshfs plugin makes using that easy. Here is how to get that installed and an example Vagrantfile that uses it:

# See: https://github.com/dustymabe/vagrant-sshfs
vagrant plugin install vagrant-sshfs

A Vagrantfile that uses sshfs and a few other interesting knobs:

Vagrant.configure(2) do |config|
    vm_memory = ENV['VM_MEMORY'] || '4000'
    vm_cpus = ENV['VM_CPUS'] || '4'

    config.ssh.forward_agent = true
    config.vm.hostname = "myvm"
    ## config.vm.network "forwarded_port", guest: 80, host: 8080
    ## or use: vagrant ssh -- -L 0.0.0.0:8080:localhost:80

    ## config.vm.network "public_network", :dev => "bridge0", :mode => "bridge", :type => "bridge"
    config.vm.network "private_network", ip: "192.168.1.10"

    ## config.vm.box = "debian/jessie64"
    ## config.vm.box = "generic/ubuntu1804"
    ## config.vm.box = "centos/7"
    config.vm.box = "centos/8"

    # Mount /vagrant via sshfs
    config.vm.synced_folder File.expand_path("."), "/vagrant", sshfs_opts_append: "-o nonempty", disabled: false, type: "sshfs"

    config.vm.provider 'libvirt' do |lb|
        # Note: Tons of other knobs you can use here. For info on that, go to:
        # https://github.com/vagrant-libvirt/vagrant-libvirt/blob/master/README.md
        lb.nested = true
        lb.memory = vm_memory
        lb.cpus = vm_cpus
        lb.suspend_mode = 'managedsave'
    end
    config.vm.provider "virtualbox" do |vb|
       # Note: Tons of other knobs you can use here. For info on that, go to:
       # https://www.virtualbox.org/manual/ch08.html#vboxmanage-modifyvm
       vb.memory = vm_memory
       vb.cpus = vm_cpus
       vb.customize ["modifyvm", :id, "--nested-hw-virt", "on"]
       vb.customize ["modifyvm", :id, "--nictype1", "virtio"]
       vb.customize ["modifyvm", :id, "--nictype2", "virtio"]
       vb.customize ['modifyvm', :id, "--nicpromisc2", "allow-all"]
       vb.customize [
           "guestproperty", "set", :id,
           "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold", 10000
          ]
    end
end

Closing

It may be worth mentioning some good vagrant-like alternatives:

• uvt-kvm: Ubuntu virtualization front-end for libvirt and KVM
• virt-builder: Build virtual machine images quickly
• virt-install: Provision new virtual machines
• ansible-virt: Ansible virt module
• Virt-Lightning: Virt-Lightning: a CLI to start local Cloud image on libvirt
• ???: Please help me make this list better!

So, next time you find yourself installing vagrant-libvirt plugin, I hope this page can make your life a little easier. Enjoy!