Conditionally show virtualbox GUI, add ssh key docs

Readme.md

@@ -9,9 +9,12 @@ cd /vagrant
 ansible-playbook playbook.yml --connection=local -i devbox, -e ansible_become=true
 
 # SSH configuration
-https://www.vagrantup.com/docs/vagrantfile/ssh_settings.html
-config.ssh.insert_key=True
+Provision own ssh key to the vagrant box. Compare [documentation|https://www.vagrantup.com/docs/vagrantfile/ssh_settings.html]
+`config.ssh.insert_key=True`
 Vagrant adds its own private/public key pair to the box. Private key will be stored on the executing box in $(pwd)/.vagrant folder.
+```
+vagrant provision devbox --provision-with shell
+```
 
 # Graphics card issues
 Issues with nvidia graphics card (NVIDIA Corporation GK106GLM [Quadro K2100M]).

Vagrantfile

@@ -40,6 +40,8 @@ Vagrant.configure("2") do |config|
     vb.cpus = 4
     vb.name = BOX_NAME
 
+    vb.gui = ENV["SHOW_GUI"] ||= "false"
+
     # https://www.virtualbox.org/manual/ch08.html
     vb.customize ["modifyvm", :id, "--vram", "128"]
     vb.customize ["modifyvm", :id, "--graphicscontroller", "vboxvga"]
@@ -67,9 +69,14 @@ Vagrant.configure("2") do |config|
   config.vm.provision "shell" do |s|
     ssh_pub_key = File.readlines("#{Dir.home}/.ssh/id_rsa.pub").first.strip
     s.inline = <<-SHELL
-      echo #{ssh_pub_key} >> /home/vagrant/.ssh/authorized_keys
-      mkdir -p /root/.ssh
-      echo #{ssh_pub_key} >> /root/.ssh/authorized_keys
+      if grep -sq "#{ssh_pub_key}" /home/vagrant/.ssh/authorized_keys; then
+        echo "SSH keys already provisioned."
+        exit 0;
+      else
+        echo #{ssh_pub_key} >> /home/vagrant/.ssh/authorized_keys
+        mkdir -p /root/.ssh
+        echo #{ssh_pub_key} >> /root/.ssh/authorized_keys
+      fi
     SHELL
   end