KVM虚拟化
一、简介
KVM（Kernel-based Virtual Machine）是一种基于Linux内核的开源虚拟化技术，它允许将物理计算机划分成多个虚拟机，每个虚拟机可以运行自己的操作系统和应用程序。
KVM支持两种虚拟化模式：半虚拟化和全虚拟化。它们的区别和优势如下
- 半虚拟化（Paravirtualization）：
在半虚拟化模式下，虚拟机的操作系统需要被修改以与宿主机进行通信。虚拟机知道自己运行在虚拟化环境中，并使用特殊的API来与宿主机进行通信。优势是效率较高，虚拟机可以直接访问宿主机的硬件设备，因此性能较好。但是，半虚拟化要求虚拟机的操作系统进行修改，这可能会限制可移植性。
- 全虚拟化（Full Virtualization）：
在全虚拟化模式下，虚拟机的操作系统不需要进行修改，它被认为是运行在真正的硬件上。KVM通过使用虚拟设备驱动程序和硬件加速来模拟硬件环境，让虚拟机能够在其自己的独立环境中运行。优势是较好的可移植性，因为虚拟机的操作系统无需进行修改。但是，全虚拟化的性能相对较低，因为需要进行额外的虚拟化和模拟。
KVM虚拟化的工作原理如下：
首先，KVM利用Linux内核的虚拟化功能创建一个虚拟化的环境，这个环境被称为虚拟机监控器（Virtual Machine Monitor，VMM）或Hypervisor。
然后，KVM使用硬件虚拟化扩展（如Intel的VT-x或AMD的AMD-V）来提供对虚拟机的支持。这些扩展使得KVM能够在每个虚拟机中运行自己的操作系统，并直接访问宿主机的硬件设备。
虚拟机监控器负责在宿主机和虚拟机之间进行资源的分配和管理。它通过为每个虚拟机提供虚拟设备（如虚拟CPU、虚拟内存和虚拟磁盘）来模拟硬件环境，使得虚拟机可以独立运行。
总的来说，KVM虚拟化技术能够提供高性能和较好的可移植性，同时对硬件要求较高。它已经成为很多云计算平台和虚拟化解决方案的首选之一。
二、KVM部署
环境
| 操作系统 | 主机名 | 部署的软件 | IP地址 |
|---|---|---|---|
| centos-7 | kvm-host | KVM | 192.168.179.20 |
| centos-7 | kvm-web | webvirtmgr（web管理界面） | 192.168.179.21 |
前期准备
两台主机都需要做的操作
开启CPU虚拟化功能
1.如果是真机，请进入BIOS界面，开启虚拟化功能
2.如果是虚拟机，请先关机，然后开启虚拟化功能，如下图：
基本配置
//配置yum源，推荐使用阿里云源。安装epel源。
[root@kvm-host ~]# rm -rf /etc/yum.repos.d/*
[root@kvm-host ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
[root@kvm-host ~]# sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo
[root@kvm-host ~]# yum clean all
[root@kvm-host ~]# yum makecache
//配置epel源
[root@kvm-host ~]# yum -y install wget
[root@kvm-host ~]# wget -O /etc/yum.repos.d/epel.repo https://mirrors.aliyun.com/repo/epel-7.repo
[root@kvm-host ~]# yum makecache
//永久关闭防火墙和selinux
[root@kvm-host ~]# systemctl disable --now firewalld.service
[root@kvm-host ~]# setenforce 0
[root@kvm-host ~]# sed -i 's/^SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
//重启主机
[root@kvm-host ~]# reboot
（另外一台主机做同样的操作）
安装KVM
在主机kvm-host上操作
//检查CPU是否支持KVM；如果结果中有vmx（Intel）或svm(AMD)字样，就说明支持。
[root@kvm-host ~]# egrep -o 'vmx|svm' /proc/cpuinfo
vmx
vmx
vmx
vmx
[root@kvm-host ~]#
//安装一些基本工具
[root@kvm-host ~]# yum -y install vim wget net-tools unzip zip gcc gcc-c++
//安装kvm
[root@kvm-host ~]# yum -y install qemu-kvm qemu-kvm-tools qemu-img virt-manager libvirt libvirt-python libvirt-client virt-install virt-viewer bridge-utils libguestfs-tools
（安装过程省略...）
//把KVM主机的网卡配置为桥接模式。
[root@kvm-host ~]# cd /etc/sysconfig/network-scripts/
[root@kvm-host network-scripts]# cp ifcfg-ens33 ifcfg-br0
[root@kvm-host network-scripts]# vim ifcfg-br0
[root@kvm-host network-scripts]# cat ifcfg-br0
TYPE="Bridge" //修改为Bridge
NM_CONTROLLED="no" //添加此行
BOOTPROTO="static"
NAME="br0" //修改为br0
DEVICE="br0" //修改为br0
ONBOOT="yes"
IPADDR="192.168.179.20"
PREFIX="24"
GATEWAY="192.168.179.2"
DNS1="8.8.8.8"
DNS2="114.114.114.114"
[root@kvm-host network-scripts]#
//原来的网卡配置成这样
[root@kvm-host network-scripts]# vim ifcfg-ens33
[root@kvm-host network-scripts]# cat ifcfg-ens33
TYPE="Ethernet"
BOOTPROTO="static"
NAME="ens33"
DEVICE="ens33"
ONBOOT="yes"
BRIDGE="br0"
NM_CONTROLLED="no"
[root@kvm-host network-scripts]#
//重启网卡服务
[root@kvm-host network-scripts]# systemctl restart network
[root@kvm-host ~]# ifdown ens33;ifup ens33
//查看，已经有br0、virbr0、virbr0-nic了，分别对应三种模式：桥接、NAT，仅主机。
[root@kvm-host network-scripts]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UP group default qlen 1000
link/ether 00:0c:29:77:15:29 brd ff:ff:ff:ff:ff:ff
inet6 fe80::20c:29ff:fe77:1529/64 scope link
valid_lft forever preferred_lft forever
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:0c:29:77:15:29 brd ff:ff:ff:ff:ff:ff
inet 192.168.179.20/24 brd 192.168.179.255 scope global br0
valid_lft forever preferred_lft forever
inet6 fe80::20c:29ff:fe77:1529/64 scope link
valid_lft forever preferred_lft forever
4: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 52:54:00:4d:e1:72 brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
valid_lft forever preferred_lft forever
5: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000
link/ether 52:54:00:4d:e1:72 brd ff:ff:ff:ff:ff:ff
[root@kvm-host network-scripts]#
//启动服务
[root@kvm-host ~]# systemctl enable --now libvirtd
//查看安装结果
[root@kvm-host ~]# lsmod|grep kvm
kvm_intel 174841 0
kvm 578518 1 kvm_intel
irqbypass 13503 1 kvm
[root@kvm-host ~]#
//安装成功
//测试并验证安装结果
[root@kvm-host ~]# virsh -c qemu:///system list
Id Name State
---------------------------------------------------- //没有问题
[root@kvm-host ~]# virsh --version
4.5.0 //版本号
[root@kvm-host ~]# virt-install --version
1.5.0
//简单配置
[root@kvm-host ~]# ln -s /usr/libexec/qemu-kvm /usr/bin/qemu-kvm
//查看网桥信息
[root@kvm-host ~]# brctl show
bridge name bridge id STP enabled interfaces
br0 8000.000c29771529 no ens33
virbr0 8000.5254004de172 yes virbr0-nic
[root@kvm-host ~]#
安装kvm web管理界面
在主机kvm-web上操作
//安装依赖包
[root@kvm-web ~]# yum -y install git python-pip libvirt-python libxml2-python python-websockify supervisor nginx python-devel
（耐心等待安装...）
//从github上下载webvirtmgr代码
[root@kvm-web src]# wget https://github.com/retspen/webvirtmgr/archive/refs/heads/master.zip
[root@kvm-web src]# yum -y install unzip
[root@kvm-web src]# unzip master.zip
[root@kvm-web src]# ls
webvirtmgr-master webvirtmgr-master.zip
//安装webvirtmgr
[root@kvm-web src]# ls
master.zip webvirtmgr-master
[root@kvm-web src]# cd webvirtmgr-master/
[root@kvm-web webvirtmgr-master]# pip install -r requirements.txt
Collecting django==1.5.5 (from -r requirements.txt (line 1))
Downloading https://files.pythonhosted.org/packages/38/49/93511c5d3367b6b21fc2995a0e53399721afc15e4cd6eb57be879ae13ad4/Django-1.5.5.tar.gz (8.1MB)
60% |███████████████████▎ | 4.9MB 2.3MB/s eta 0:00:02
（耐心等待安装...）
//检查sqlite3是否安装
[root@kvm-web webvirtmgr-master]# python
Python 2.7.5 (default, Jun 20 2023, 11:36:40)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlite3 //输入这条命令，如果没有任何反馈，就没问题
>>> exit() //退出
[root@kvm-web webvirtmgr-master]#
//初始化帐号信息
[root@kvm-web webvirtmgr-master]# python manage.py syncdb
WARNING:root:No local_settings file found.
Creating tables ...
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_groups
Creating table auth_user_user_permissions
Creating table auth_user
Creating table django_content_type
Creating table django_session
Creating table django_site
Creating table servers_compute
Creating table instance_instance
Creating table create_flavor
You just installed Django's auth system, which means you don't have any superusers defined.
Would you like to create one now? (yes/no): yes //询问你，是否创建一个超级管理员，yes
Username (leave blank to use 'root'): admin //用户名，是web页面的管理员，非系统用户
Email address: 1@2.com //邮箱，根据实际填
Password: //输入密码
Password (again): //再次输入密码
Superuser created successfully.
Installing custom SQL ...
Installing indexes ...
Installed 6 object(s) from 1 fixture(s)
[root@kvm-web webvirtmgr-master]#
//拷贝web网页至指定目录
[root@kvm-web webvirtmgr-master]# mkdir /var/www
[root@kvm-web webvirtmgr-master]# cp -r /usr/local/src/webvirtmgr-master/ /var/www/
[root@kvm-web webvirtmgr-master]# chown -R nginx.nginx /var/www/webvirtmgr-master/
//给本机的root用户配置免密登录
//生成密钥
[root@kvm-web ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): //回车
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase): //回车
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is: //回车
SHA256:x3g8rKS/7YGHTnfaQH6C+hyCWps+q2psP3cP2N1HOyA root@kvm-web
The key's randomart image is:
+---[RSA 2048]----+
| |
| |
| |
| = |
| SEO. . |
| .oo.Xo.o . |
|. o.ooB.B.o+ |
| + +.+ O.= O. . |
|+.++Boo.B++ . |
+----[SHA256]-----+
[root@kvm-web ~]#
//发送密钥给kvm主机
[root@kvm-web ~]# ssh-copy-id 192.168.179.20
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.179.20 (192.168.179.20)' can't be established.
ECDSA key fingerprint is SHA256:FUBajMDXZl+SPT7to3Z/OhKLk0INYLP7iXNsAjaZq7g.
ECDSA key fingerprint is MD5:3e:5b:91:c7:e2:93:e6:2f:73:55:ac:7d:a3:7b:5c:04.
Are you sure you want to continue connecting (yes/no)? yes //输入yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
[email protected]'s password: //输入该主机的root密码
Number of key(s) added: 1
Now try logging into the machine, with: "ssh '192.168.179.20'"
and check to make sure that only the key(s) you wanted were added.
[root@kvm-web ~]#
//root用户可以免密登录对方主机
[root@kvm-web ~]# ssh [email protected]
Last login: Wed Oct 11 16:17:34 2023 from kvm-host
[root@kvm-host ~]# exit
logout
Connection to 192.168.179.20 closed.
[root@kvm-web ~]#
//配置端口转发
[root@kvm-web ~]# ssh 192.168.179.20 -L localhost:8000:localhost:8000 -L localhost:6080:localhost:60
Last login: Wed Oct 11 16:22:25 2023 from 192.168.179.1
[root@kvm-host ~]# exit //记得退出来
logout
Connection to 192.168.179.20 closed.
[root@kvm-web ~]#
//配置nginx
//先备份原配置文件
[root@kvm-web ~]# mv /etc/nginx/nginx.conf /opt/
//再手动创建一个新配置文件，内容如下
[root@kvm-web ~]# vim /etc/nginx/nginx.conf
[root@kvm-web ~]# cat /etc/nginx/nginx.conf
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;
events {
worker_connections 1024;
}
http {
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
include /etc/nginx/mime.types;
default_type application/octet-stream;
include /etc/nginx/conf.d/*.conf;
server {
listen 80;
server_name localhost;
include /etc/nginx/default.d/*.conf;
location / {
root html;
index index.html index.htm;
}
error_page 404 /404.html;
location = /40x.html {
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
}
}
}
[root@kvm-web ~]#
//手动配置nginx虚拟主机
[root@kvm-web ~]# vim /etc/nginx/conf.d/webvirtmgr.conf
[root@kvm-web ~]# cat /etc/nginx/conf.d/webvirtmgr.conf
server {
listen 80 default_server;
server_name $hostname;
#access_log /var/log/nginx/webvirtmgr_access_log;
location /static/ {
root /var/www/webvirtmgr-master/webvirtmgr;
expires max;
}
location / {
proxy_pass http://127.0.0.1:8000;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-for $proxy_add_x_forwarded_for;
proxy_set_header Host $host:$server_port;
proxy_set_header X-Forwarded-Proto $remote_addr;
proxy_connect_timeout 600;
proxy_read_timeout 600;
proxy_send_timeout 600;
client_max_body_size 1024M;
}
}
[root@kvm-web ~]#
//确保bind绑定的是本机的8000端口
[root@kvm-web ~]# vim /var/www/webvirtmgr-master/conf/gunicorn.conf.py
（省略）
bind = '0.0.0.0:8000' //修改为0.0.0.0:8000
backlog = 2048
（省略）
//重启nginx
[root@kvm-web ~]# systemctl restart nginx.service
[root@kvm-web ~]# systemctl enable nginx.service
Created symlink from /etc/systemd/system/multi-user.target.wants/nginx.service to /usr/lib/systemd/system/nginx.service.
[root@kvm-web ~]#
//设置supervisor，直接在最后面添加以下内容
[root@kvm-web ~]# vim /etc/supervisord.conf
（省略）
[program:webvirtmgr-master]
command=/usr/bin/python2 /var/www/webvirtmgr-master/manage.py run_gunicorn -c /var/www/webvirtmgr-master/conf/gunicorn.conf.py
directory=/var/www/webvirtmgr-master
autostart=true
autorestart=true
logfile=/var/log/supervisor/webvirtmgr-master.log
log_stderr=true
user=nginx
[program:webvirtmgr-console]
command=/usr/bin/python2 /var/www/webvirtmgr-master/console/webvirtmgr-console
directory=/var/www/webvirtmgr-master
autostart=true
autorestart=true
stdout_logfile=/var/log/supervisor/webvirtmgr-console.log
redirect_stderr=true
user=nginx
//启动supervisor并设置开机自启
[root@kvm-web ~]# systemctl start supervisord && systemctl enable supervisord
Created symlink from /etc/systemd/system/multi-user.target.wants/supervisord.service to /usr/lib/systemd/system/supervisord.service.
[root@kvm-web ~]#
//配置nginx用户
//给本机的nginx用户配置免密登录
[root@kvm-web ~]# su - nginx -s /bin/bash
-bash-4.2$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/var/lib/nginx/.ssh/id_rsa):
Created directory '/var/lib/nginx/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /var/lib/nginx/.ssh/id_rsa.
Your public key has been saved in /var/lib/nginx/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:7yQztH2aDeJ4fK733bap+RMKxmIkH2NYoryC2uo0EXc nginx@kvm-web
The key's randomart image is:
+---[RSA 2048]----+
| |
| . . |
| . ..E. + |
| o .o o = |
| .. . S + |
| ... . . B + . |
|.+ . .B B o . .|
|o o ooBo* o.oo|
|oo ..o==.oo+=+|
+----[SHA256]-----+
-bash-4.2$ touch ~/.ssh/config && echo -e "StrictHostKeyChecking=no\nUserKnownHostsFile=/dev/null" >> ~/.ssh/config
-bash-4.2$ chmod 0600 ~/.ssh/config
-bash-4.2$ ssh-copy-id [email protected]
/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/var/lib/nginx/.ssh/id_rsa.pub"
/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
Warning: Permanently added '192.168.179.20' (ECDSA) to the list of known hosts.
[email protected]'s password:
Number of key(s) added: 1
Now try logging into the machine, with: "ssh '[email protected]'"
and check to make sure that only the key(s) you wanted were added.
-bash-4.2$ exit
logout
[root@kvm-web ~]#
//生成配置文件
[root@kvm-web ~]# vim /etc/polkit-1/localauthority/50-local.d/50-libvirt-remote-access.pkla
[root@kvm-web ~]# cat /etc/polkit-1/localauthority/50-local.d/50-libvirt-remote-access.pkla
[Remote libvirt SSH access]
Identity=unix-user:root
Action=org.libvirt.unix.manage
ResultAny=yes
ResultInactive=yes
ResultActive=yes
[root@kvm-web ~]#
//修改权限
[root@kvm-web ~]# chown -R root.root /etc/polkit-1/localauthority/50-local.d/50-libvirt-remote-access.pkla
//重启nginx服务
[root@kvm-web ~]# systemctl restart nginx
//重启kvm主机上的kvm服务
[root@kvm-web ~]# ssh [email protected] "systemctl restart libvirtd"
//建议重启一下主机kvm-web
[root@kvm-web ~]# reboot
实例管理
在浏览器访问kvm-web主机的IP地址
使用创建的超级管理员登录
kvm连接管理
创建ssh连接
kvm存储管理
创建存储
进入存储
通过远程连接软件上传ISO镜像文件到/var/lib/libvirt/images 中
//查看上传的ISO镜像文件
[root@kvm-host ~]# cd /var/lib/libvirt/images/
[root@kvm-host images]# ls
CentOS-Stream-8-20230626.1-x86_64-dvd1.iso
[root@kvm-host images]#
创建系统安装镜像
kvm网络管理
添加桥接网络
kvm虚机实例管理
创建一个虚拟机
进入虚拟机系统安装界面
进行正常安装系统的操作，过程省略
注意：虚拟主机中网卡要配和kvm主机一样的网段，本案例的kvm主机是192.168.179.0/24网段的，所以虚拟主机也要配此网段的ip地址
通过xshell软件ssh远程连接这台虚拟机
//查看ip：IP地址为192.168.179.18/24
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 52:54:00:f5:67:23 brd ff:ff:ff:ff:ff:ff
altname enp0s3
inet 192.168.179.18/24 brd 192.168.179.255 scope global noprefixroute ens3
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fef5:6723/64 scope link noprefixroute
valid_lft forever preferred_lft forever
[root@localhost ~]#
//可以上网
[root@localhost ~]# ping -c4 www.baidu.com
PING www.a.shifen.com (36.155.132.55) 56(84) bytes of data.
64 bytes from 36.155.132.55 (36.155.132.55): icmp_seq=1 ttl=128 time=51.5 ms
64 bytes from 36.155.132.55 (36.155.132.55): icmp_seq=2 ttl=128 time=73.9 ms
64 bytes from 36.155.132.55 (36.155.132.55): icmp_seq=3 ttl=128 time=80.6 ms
64 bytes from 36.155.132.55 (36.155.132.55): icmp_seq=4 ttl=128 time=79.10 ms
--- www.a.shifen.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3005ms
rtt min/avg/max/mdev = 51.527/71.483/80.575/11.815 ms
[root@localhost ~]#