Base VagrantFile to use ssh with custom username & custom public key

Vagrantfile

Vagrant.configure("2") do |config|
  # Define vm box
  config.vm.box = "gbailey/amzn2"
  # Constraint vm box version
  config.vm.box_version = "20210127.0.0"
  
  # Copy public key from host to guest
  # Prerequisite: need to have id_rsa.pub in host machine
  # Use ssh-keygen to create keys in path e.g. Windows C:\Users\<USER_NAME>\.ssh\id_rsa/pub
  config.vm.provision "file", source: "~/.ssh/id_rsa.pub", destination: "~/.ssh/id_rsa.pub"
  # Append copied public key to target ssh username authorized_keys
  config.vm.provision "shell", inline: <<-SHELL
    sudo cat /home/vagrant/.ssh/id_rsa.pub >> /home/ec2-user/.ssh/authorized_keys
  SHELL

  # Ssh using target username
  VAGRANT_COMMAND = ARGV[0]
  if VAGRANT_COMMAND == "ssh"
    config.ssh.username = "ec2-user"
    config.ssh.private_key_path = "C:/Users/<USER_NAME>/.ssh/id_rsa"
  end
end