Vagrant + Virtualbox 建立 Ubuntu VM on Mac

1. 下載並安裝Vagrant：
https://www.vagrantup.com/downloads.html

2. 下載並安裝VirtualBox：
https://www.virtualbox.org/wiki/Downloads

3. 進終端機後找一個喜歡的路徑，在之下建立一個專案資料夾，並進到該資料夾，例：

% mkdir vagrant && cd vagrant

4. 初始化一個Ubuntu 20.04：

% vagrant init bento/ubuntu-20.04

5. Vagrant會在該目錄下建立一個Vagrantfile，目前先不用編輯它

A `Vagrantfile` has been placed in this directory. You are now
ready to `vagrant up` your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
`vagrantup.com` for more information on using Vagrant.

6. 起動這個虛擬機，Vagrant會開始下載Ubuntu 20.04 的映像檔，如果中途有詢問要用哪一種VM服務，請選 Virtualbox，如果Mac已經安裝了Virtualbox，預設會使用Virtualbox：

% vagrant up

跑一段時間後會看到：

Bringing machine 'default' up with 'virtualbox' provider...
==> default: Box 'bento/ubuntu-20.04' could not be found. Attempting to find and install...
    default: Box Provider: virtualbox
    default: Box Version: >= 0
==> default: Loading metadata for box 'bento/ubuntu-20.04'
    default: URL: https://vagrantcloud.com/bento/ubuntu-20.04
==> default: Adding box 'bento/ubuntu-20.04' (v202012.23.0) for provider: virtualbox
    default: Downloading: https://vagrantcloud.com/bento/boxes/ubuntu-20.04/versions/202012.23.0/providers/virtualbox.box
Download redirected to host: vagrantcloud-files-production.s3.amazonaws.com
==> default: Successfully added box 'bento/ubuntu-20.04' (v202012.23.0) for 'virtualbox'!
==> default: Importing base box 'bento/ubuntu-20.04'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'bento/ubuntu-20.04' version '202012.23.0' is up to date...
==> default: Setting the name of the VM: vagrant_default_1610699516472_87684
Vagrant is currently configured to create VirtualBox synced folders with
the `SharedFoldersEnableSymlinksCreate` option enabled. If the Vagrant
guest is not trusted, you may want to disable this option. For more
information on this option, please refer to the VirtualBox manual:

  https://www.virtualbox.org/manual/ch04.html#sharedfolders

This option can be disabled globally with an environment variable:

  VAGRANT_DISABLE_VBOXSYMLINKCREATE=1

or on a per folder basis within the Vagrantfile:

  config.vm.synced_folder '/host/path', '/guest/path', SharedFoldersEnableSymlinksCreate: false
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
    default: 
    default: Vagrant insecure key detected. Vagrant will automatically replace
    default: this with a newly generated keypair for better security.
    default: 
    default: Inserting generated public key within guest...
    default: Removing insecure key from the guest if it's present...
    default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
==> default: Mounting shared folders...
    default: /vagrant => /Users/maki/vagrant

7. 進入VM並使用sudo權限（不需密碼）

% vagrant ssh
# sudo su

就可以開始用Ubuntu VM了