在 Ubuntu 上构建KVM 云镜像

April 9, 2018

如何在 Ubuntu Linux 16.04 LTS 服务器上无需完整安装即可创建虚拟机？如何在 Ubuntu Linux 上使用 KVM 云镜像？

基于内核的虚拟机（KVM）是 Linux 内核的虚拟化模块，可将其转变为虚拟机管理程序。你可以在命令行使用 Ubuntu 为 libvirt 和 KVM 提供的虚拟化前端通过 KVM 创建 Ubuntu 云镜像。

这个快速教程展示了如何安装和使用 uvtool，它为 Ubuntu 云镜像下载，libvirt 和 clout_int 提供了统一的集成虚拟机前端。

###步骤 1 - 安装 KVM
```
$ sudo apt install qemu-kvm libvirt-bin virtinst bridge-utils cpu-checker
$ kvm-ok
## [configure bridged networking as described here][3]
$ sudo vi /etc/network/interfaces
$ sudo systemctl restart networking
$ sudo brctl show
```
参阅如何在 [Ubuntu 16.04 LTS Headless 服务器上安装 KVM](https://www.cyberciti.biz/faq/installing-kvm-on-ubuntu-16-04-lts-server/ "Ubuntu 16.04 LTS Headless 服务器上安装 KVM") 以获得更多信息。
###步骤 2 - 安装 uvtool
```
$ sudo apt install uvtool
```
输出
```
[sudo] password for vivek: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  gksu libgksu2-0 libqt5designer5 libqt5help5 libqt5printsupport5 libqt5sql5 libqt5sql5-sqlite libqt5xml5 python3-dbus.mainloop.pyqt5 python3-notify2 python3-pyqt5 python3-sip
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  cloud-image-utils distro-info python-boto python-pyinotify python-simplestreams socat ubuntu-cloudimage-keyring uvtool-libvirt
Suggested packages:
  cloud-utils-euca shunit2 python-pyinotify-doc
The following NEW packages will be installed:
  cloud-image-utils distro-info python-boto python-pyinotify python-simplestreams socat ubuntu-cloudimage-keyring uvtool uvtool-libvirt
0 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Need to get 1,211 kB of archives.
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Get:7 http://in.archive.ubuntu.com/ubuntu artful/universe amd64 socat amd64 1.7.3.2-1 [342 kB]
Get:8 http://in.archive.ubuntu.com/ubuntu artful/universe amd64 uvtool all 0~git122-0ubuntu1 [6,498 B]
Get:9 http://in.archive.ubuntu.com/ubuntu artful/universe amd64 uvtool-libvirt all 0~git122-0ubuntu1 [26.9 kB]
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```
###步骤 3 - 下载 Ubuntu 云镜像
你需要使用 uvt-simplestreams-libvirt 命令。它维护一个 libvirt 容量存储池，作为一个简单流simplestreams源的镜像子集的本地镜像，比如 Ubuntu 云镜像。要使用当前所有 amd64 镜像更新 uvtool 的 libvirt 容量存储池，运行：
```
$ uvt-simplestreams-libvirt sync arch=amd64
```
要更新/获取 Ubuntu 16.04 LTS (xenial/amd64) 镜像，运行：
```
$ uvt-simplestreams-libvirt --verbose sync release=xenial arch=amd64
```
示例输出：
```
Adding: com.ubuntu.cloud:server:16.04:amd64 20171121.1
```
通过 query 选项查询本地镜像：
```
$ uvt-simplestreams-libvirt query
```
示例输出：

```
release=xenial arch=amd64 label=release (20171121.1)
```
现在，我为 Ubuntu xenial 创建了一个镜像，接下来我会创建虚拟机。
###步骤 4 - 创建 VM
是时候创建虚拟机了，它叫 vm1，即创建一个 Ubuntu Linux 16.04 LTS 虚拟机：
```
$ uvt-kvm create vm1
```
默认情况下 vm1 使用以下配置创建：

内存：512M
磁盘大小：8GiB
CPU：1 vCPU core
要控制内存、磁盘、CPU 和其他配置，使用以下语法：
```
$ uvt-kvm create vm1 \
--memory MEMORY \
--cpu CPU \
--disk DISK \
--bridge BRIDGE \
--ssh-public-key-file /path/to/your/SSH_PUBLIC_KEY_FILE \
--packages PACKAGES1, PACKAGES2, .. \
--run-script-once RUN_SCRIPT_ONCE \
--password PASSWORD
```
其中

--password PASSWORD：设置 ubuntu 用户的密码和允许使用 ubuntu 的用户登录（不推荐，使用 ssh 密钥）。
--run-script-once RUN_SCRIPT_ONCE : 第一次启动时，在虚拟机上以 root 身份运行 RUN_SCRIPT_ONCE 脚本，但再也不会运行。这里给出完整的路径。这对于在虚拟机上运行自定义任务时非常有用，例如设置安全性或其他内容。
--packages PACKAGES1, PACKAGES2, .. : 在第一次启动时安装以逗号分隔的软件包。
要获取帮助，运行：
```
$ uvt-kvm -h
$ uvt-kvm create -h
```
####如何删除虚拟机？
要销毁/删除名为 vm1 的虚拟机，运行（请小心使用以下命令，因为没有确认框）：
```
$ uvt-kvm destroy vm1
```
####获取 vm1 的 IP 地址，运行：
```
$ uvt-kvm ip vm1
192.168.122.52
```
####列出所有运行的虚拟机
```
$ uvt-kvm list
```
###步骤 5 - 如何登录 vm
语法是：
```
$ uvt-kvm ssh vm1
```
示例输出：
```
Welcome to Ubuntu 16.04.3 LTS (GNU/Linux 4.4.0-101-generic x86_64)
 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage
  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud
0 packages can be updated.
0 updates are security updates.
Last login: Thu Dec  7 09:55:06 2017 from 192.168.122.1
```
另一个选择是从 macOS/Linux/Unix/Windows 客户端使用常规的 ssh 命令：
```
$ ssh ubuntu@192.168.122.52
$ ssh -i ~/.ssh/id_rsa ubuntu@192.168.122.52
```
一旦创建了 vim，你可以照常使用 virsh 命令：
```
$ virsh list
```

引用：
1. https://www.cyberciti.biz/faq/how-to-use-kvm-cloud-images-on-ubuntu-linux/
2. https://linux.cn/article-9522-1.html

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