Vagrant (三) - 網絡配置

這個章節脫胎於我早期的blog文章，訂正了一下句法和準確性。

原始的文字在 VAGRANT 網絡配置 (HIDE)

網絡配置

Vagrant能夠指定三種網絡：端口轉發（Forwarded Ports），私有網絡（Private Network），公有網絡（Public Network）。他們和多數虛擬機提供的網絡是對應的。

Vagrant 網絡模型

端口轉發：

config.vm.network :forwarded_port, guest: 80, host: 8080

將虛擬機（被稱做guest）的端口80映射爲宿主機的端口8080。

端口轉發隱含着一個provider的NAT網絡將被首先建立。
因此，若是你單獨定義一條端口轉發的配置語句的話，VM將會自動創建NAT網絡環境。

私有網絡：

config.vm.network :private_network, ip: "192.168.1.104"

你能夠從宿主機自由訪問虛擬機，但LAN網絡中的其餘人不須要也沒法訪問虛擬機。

值得注意的是，ip地址「192.168.1.104」不是隨便指定的。
首先你能夠不指定，這表示虛機啓動時會DHCP到一個可用的IP地址（例如：192.168.33.101），這是vagrant經過virtualbox私有網絡的DHCP機制得到的。
若是你要自行指定明確的IP地址，要保證該地址是在恰當的網段中，例如192.168.33.71。

多臺虛擬機在私有網絡模式下也能夠互相訪問，只要設置爲相同的網段就能夠。

本質上說，這是使用provider的HostOnly模式。

公有網絡：

公有網絡其實是表示將虛擬機暴露爲LAN（例如你的宿主機所在的辦公室網絡）中的一臺主機。

例如使用LAN的DHCP自動得到IP地址：

config.vm.network :public_network

也能夠指定LAN網段中的一個可用的地址，但須要注意不要和LAN中已有的主機或者保留的IP地址相沖突。

本質上說，這是使用provider的橋接網絡模式。

Provider的網絡模式

對於vagrant的provider，例如VirtualBox來講，網絡模式區分的更細，但vagrant並不能使用所有vbox網絡模型。

VirtualBox 的典型網絡模型：NAT，Hostonly，Bridge以及Internal。

這些模式的細節咱們再也不列舉。

借用一張表格來概括：

	NAT	Bridged	Internal	Hostonly
vm -> host	√	√	×	×
host -> vm	×	√	×	×
vm -> others hosts	√	√	×	×
others hosts => vm	×	√	×	×
vm <-> vm	×	√	same subnet	√

這張表格描述了virtualbox的網絡模型。

實用的網絡配置

通常來講，端口轉發足以知足開發須要了。

但對於特殊的須要來講，你可能須要一臺徹底「真實」的虛機，這臺虛機能夠被穩定地從宿主機訪問，而且能夠訪問LAN中的其餘資源。這樣的需求實際上能夠經過配置多塊網卡來解決問題，例如一塊配置爲私有網絡模式，一塊配置爲公有網絡模式。

vagrant經過配置文件可以支持virtualbox的NAT，Bridge以及Hostonly網絡模型。

默認狀況

默認狀況下，咱們已經知道一個最簡的流程來啓動vagrant：

mkdir /dev
    cd /dev
    vagrant box add ubuntu/trusty64
    vagrant init ubuntu/trusty64
    vagrant up
    vagrant ssh
    vagrant halt

這樣的步驟，能夠獲得一臺ubuntu 14.04的虛擬機，採用Provider的NAT網絡模式，在虛擬機中能夠訪問宿主機，也可使用宿主機的外網路由上網。

觀察它生成的默認的Vagranfile，其網絡配置是未指定的。

此時，vagrant創建的vm具備一個NAT網卡。

橋接網絡

當採用以下配置語句時，vagrant創建的vm具備一個Bridged網絡：

# Create a public network, which generally matched to bridged network.
# Bridged networks make the machine appear as another physical device on
# your network.
config.vm.network "public_network"

此時，vm在宿主機所在的LAN中等價於一臺物理機器。假如你具備LAN Router的管理權的話，這是很簡單的一種開發模型：經過路由器的mac綁定爲vm保留一個固定的dhcp地址，這樣vm不管什麼時候啓動都會獲取到相同的IP地址，你的開發和調試將會很順利很簡單。

私有網絡

當採用以下配置語句時，vagrant創建的vm具備兩個hostonly網絡：

config.vm.network "private_network", ip: "192.168.9.10"
config.vm.network "private_network", ip: "192.168.33.10"

標識符「private_network」老是被映射爲virtualbox的hostonly模型。

私有網絡模型是容許宿主機訪問的，爲了便於宿主機訪問，咱們也能夠明確指定一個適當網段的地址。要知道適當的網段是多少，能夠這樣查證：

• 經過進入虛機顯示網卡信息和IP地址來了解網段。
• 打開 VirtualBox 的網絡配置，檢查HostOnly網絡的DHCP網段。

混合網絡

當採用以下配置語句時，vagrant創建的vm具備一個NAT和一個hostonly網絡：

config.vm.network "private_network", ip: "192.168.33.10"

標識符「private_network」老是被映射爲virtualbox的hostonly模型。

注意 NAT 網絡將被隱含地建立。
vagrant在建立網卡時，若是配置文件僅配置了一個private_network，則vagrant自動建立NAT網卡，而後在建立配置文件所描述的網絡；而若是配置文件指定了兩個以上的private_network的話，vagrant再也不自動建立 NAT 網卡了。

混合網絡很是適合開發和測試環境，你能夠經過NAT和Internet相通，而後多個vm之間也能相互通訊。

內外網絡

內外網絡 只是我隨便命名的，也就是從vm的角度出發既有內網（VM的私有網絡），又有外網（宿主機所在的局域網）。

當採用以下配置語句時，vagrant創建的vm具備一個bridged和一個hostonly網絡：

config.vm.network "public_network"
config.vm.network "private_network", ip: "192.168.33.10"

這是比較通用的配置模式，vm既有host主機所在局域網的ip，又有一個私有網絡的ip地址，所以這些vm之間具備全連通性。

不過，通常來講開發和測試使用較爲封閉的網絡模型是比較好的方式，一般不建議vm配置有 public_network 的網卡。

小結

任何

config.vm.network "private_network", ip: "192.168.33.10"

語句均可以改成：

config.vm.network "private_network", type: "dhcp"

這時virtualbox的網關負責dhcp應答和分配IP。

實例

nginx服務

1. 創建一個新的工做目錄 sample-nginx
2. 使用 vagrant init ubuntu/xenial64 進行初始化
3. 修改 Vagrantfile 加入必要的聲明 (見後)
4. 使用 vagrant up 啓動該虛擬機，而後能夠SSH進入或者 curl -i http://localhost:8080/ 來嘗試訪問它

完整的 Vagrantfile 以下：

# -*- mode: ruby -*-
# vi: set ft=ruby :

# All Vagrant configuration is done below. The "2" in Vagrant.configure
# configures the configuration version (we support older styles for
# backwards compatibility). Please don't change it unless you know what
# you're doing.
Vagrant.configure("2") do |config|
  # The most common configuration options are documented and commented below.
  # For a complete reference, please see the online documentation at
  # https://docs.vagrantup.com.

  # Every Vagrant development environment requires a box. You can search for
  # boxes at https://vagrantcloud.com/search.
  config.vm.box = "ubuntu/xenial64"
  
  # Disable automatic box update checking. If you disable this, then
  # boxes will only be checked for updates when the user runs
  # `vagrant box outdated`. This is not recommended.
  # config.vm.box_check_update = false

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine. In the example below,
  # accessing "localhost:8080" will access port 80 on the guest machine.
  # NOTE: This will enable public access to the opened port
  config.vm.network "forwarded_port", guest: 80, host: 8080

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine and only allow access
  # via 127.0.0.1 to disable public access
  # config.vm.network "forwarded_port", guest: 80, host: 8080, host_ip: "127.0.0.1"

  # Create a private network, which allows host-only access to the machine
  # using a specific IP.
  # config.vm.network "private_network", ip: "192.168.33.10"

  # Create a public network, which generally matched to bridged network.
  # Bridged networks make the machine appear as another physical device on
  # your network.
  # config.vm.network "public_network"

  # Share an additional folder to the guest VM. The first argument is
  # the path on the host to the actual folder. The second argument is
  # the path on the guest to mount the folder. And the optional third
  # argument is a set of non-required options.
  # config.vm.synced_folder "../data", "/vagrant_data"

  # Provider-specific configuration so you can fine-tune various
  # backing providers for Vagrant. These expose provider-specific options.
  # Example for VirtualBox:
  #
  # config.vm.provider "virtualbox" do |vb|
  #   # Display the VirtualBox GUI when booting the machine
  #   vb.gui = true
  #
  #   # Customize the amount of memory on the VM:
  #   vb.memory = "1024"
  # end
  #
  # View the documentation for the provider you are using for more
  # information on available options.

  # Enable provisioning with a shell script. Additional provisioners such as
  # Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the
  # documentation for more information about their specific syntax and use.
  config.vm.provision "shell", inline: <<-SHELL
    apt-get update
    apt-get install -y nginx
  SHELL
end

這是一個至關簡單的實例。更復雜的初始化，能夠考慮使用一個獨立的腳本文件來完成，而不是直接放在 Vagrantfile 中。

Updates

有時候，可能遇到網絡配置失敗的狀況。例如：

$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'ubuntu/bionic64'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'ubuntu/bionic64' is up to date...
==> default: Setting the name of the VM: setup_bionic_default_1511875921207_73707
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
    default: Adapter 2: hostonly
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> 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: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    default: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    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: The guest additions on this VM do not match the installed version of
    default: VirtualBox! In most cases this is fine, but in rare cases it can
    default: prevent things such as shared folders from working properly. If you see
    default: shared folder errors, please make sure the guest additions within the
    default: virtual machine match the version of VirtualBox you have installed on
    default: your host and reload your VM.
    default: 
    default: Guest Additions Version: 5.1.28_Ubuntu r117968
    default: VirtualBox Version: 5.2
==> default: Configuring and enabling network interfaces...
The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

/sbin/ifdown 'enp0s8' || true
/sbin/ip addr flush dev 'enp0s8'
# Remove any previous network modifications from the interfaces file
sed -e '/^#VAGRANT-BEGIN/,$ d' /etc/network/interfaces > /tmp/vagrant-network-interfaces.pre
sed -ne '/^#VAGRANT-END/,$ p' /etc/network/interfaces | tac | sed -e '/^#VAGRANT-END/,$ d' | tac > /tmp/vagrant-network-interfaces.post

cat \
  /tmp/vagrant-network-interfaces.pre \
  /tmp/vagrant-network-entry \
  /tmp/vagrant-network-interfaces.post \
  > /etc/network/interfaces

rm -f /tmp/vagrant-network-interfaces.pre
rm -f /tmp/vagrant-network-entry
rm -f /tmp/vagrant-network-interfaces.post

/sbin/ifup 'enp0s8'

Stdout from the command:



Stderr from the command:

bash: line 4: /sbin/ifdown: No such file or directory
sed: can't read /etc/network/interfaces: No such file or directory
sed: can't read /etc/network/interfaces: No such file or directory
bash: line 20: /sbin/ifup: No such file or directory

這是因爲 vagrant 使用 ifupdown 軟件包來管理虛擬機的網絡配置問題，然而某些新版本的操做系統，例如 Ubuntu 18+ 已經放棄了 ifupdown，於是 vagrant 腳本會失敗。

解決的辦法是兩次啓動虛擬機，而且在其間自行安裝 ifupdown：

$ vagrant up   # 啓動虛擬機，會報錯網絡配置不成功
$ vagrant ssh  # 不理睬錯誤直接登陸到虛擬機中
ubuntu@node1$ sudo apt install ifupdown; exit
$ vagrant halt # 關閉虛擬機
$ vargant up && vagrant ssh # 而後從新啓動虛擬機，網絡配置會再次被應用，而且應該會一切正常了

References

• https://www.virtualbox.org/ma...
• https://dev.to/isabolic99/how...
• https://www.vagrantup.com/doc...