gistfile1.rb

require 'etc'

ssh_user = Etc.getlogin
public_key_path = "~/.ssh/id_dsa.pub"
ssh_public_key = File.read(File.expand_path(public_key_path)).strip
Vagrant.configure("2") do |config|
  ....

  config.vm.provision :shell, :inline => "cat >>/tmp/ssh_key_pub <<EOF\n#{ssh_public_key}\nEOF"
  config.vm.provision :shell, :inline => "cat >>/tmp/ssh_user <<EOF\n#{ssh_user}\nEOF"
  config.vm.provision :shell, :path => "provision-user.sh"

  ..
end