Vagrants synced folders over NFS do not work with libvirt provider

Vagrant
1

Hi there,

I am currently trying to use Vagrant on my Arch based Linux system. I setup a Vagrantfile that starts with

Vagrant.configure("2") do |config|
  config.vm.provider :libvirt do |libvirt|
    # setup VM parameters
    libvirt.memory = "1024"
    libvirt.cpus = 4
  end
  config.vm.box =  "centos/7"
  config.vm.synced_folder ".", "/vagrant", type: "nfs"
  # configure a macvtap device to get an IP from the host network
  config.vm.network :public_network,
      :dev => "enp8s0",
      :mode => "bridge",
      :type => "direct"
end

The problem is vagrant up, that is supposed to setup the virtual machine, fails during the step it should setup the NFS synced folders between the host and the guest:

[...]
==> default: Mounting NFS shared folders...
==> default: Pruning invalid NFS exports. Administrator privileges will be required...
==> default: Removing domain...
==> default: Deleting the machine folder
The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

mount -o vers=3,udp 192.168.121.1:/home/sapiens/Code/vagrant-private/printing-server /vagrant

Stdout from the command:



Stderr from the command:

mount.nfs: requested NFS version or transport protocol is not supported

I have opened ports 111 2049 20048 32765 and 32803 for NFS in the firewall, still this fails. I do not know what I am doing wrong! I appreciate any help!

2

Ok, I kinda solved the issue.
Changing

  config.vm.synced_folder ".", "/vagrant", type: "nfs"

to

  config.vm.synced_folder ".", "/vagrant", type: "nfs", mount_options: ["vers=3,tcp"]

Makes it work, I however do not understand why! If anyone can make me understand I would be glad!