vagrant guest additions and kernel - vagrant

Question

Getting a 'vboxsf' error whenever I try to up the centos7 box.
I run vagrant init in the directory.Then I go in directory and edit the file.And run the vagrant up.This is what I put in vagrant file:-
# -*- mode: ruby -*-
# vi: set ft=ruby :
Vagrant.configure("2") do |config|
config.vm.define "Centos7" do |master|
master.vm.provider "virtualbox"
master.vm.box = "centos/7"
master.vm.hostname = "web.mylab.local"
master.vm.network :private_network, ip: "198.168.56.7"
config.vm.synced_folder ".", "/vagrant", type: "virtualbox"
master.vm.provision "shell", inline: <<-SHELL
sudo sed -1 "s/PasswordAuthentication.*/PasswordAuthentication
yes/g" /etc/ssh/sshd_config
sudo systemct1 restart sshd
SHELL
end
end
**This is the error message i get:-**
Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:
mount -t vboxsf -o uid=1000,gid=1000 vagrant /vagrant
The error output from the command was:
mount: unknown filesystem type 'vboxsf'

Answer 1

You are defining a synced_folder (i.e. shared folder) for your VirtualBox vm.
This functionality requires the vm to have the VirtualBox Guest Additions installed
You are using a base box that does not have VirtualBox Guest Additions installed
From there you basically have 3 options
Modify your vagrant provisioning script to install Guest Additions when creating the vm (e.g. Insert the virtual CDROM into vm, mount it and lauch the install script). I still have a doubt this can break in case the shared folder mount happens before provisionning is finished...
Create a base box yourself that will have Guest Additions installed and use it. If you need to share this box with other devs, you will have to host it somewhere.
Use an other base box with Guest Additions already installed.
I did not dig into the latest point for quite a while since I tend to craft my own boxes for my own use. But if I remember well, the public generic/centos7 box comes with Guest Additions pre-installed for the VirtualBox provider.