KVM虚机PXE方式自动安装
示例拓扑如下，DHCP、TFTP、HTTP、PXE Server在1台主机上部署，KVM宿主机与NFS server分别在另2台主机上部署。KVM虚机PXE方式自动安装示例-2629585-1
确认主机CPU支持并打开了虚拟化支持（Intel/AMD）,如果是多核CPU会有多个核的信息：
# egrep '(vmx|svm)' /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm epb tpr_shadow vnmi ept vpid fsgsbase tsc_adjust smep dtherm arat pln pts
确认主机加载了KVM内核模块并是在用状态：
# lsmod | grep kvm
kvm_intel 1700868
kvm 5663401 kvm_intel
irqbypass 135031 kvm
在KVM上创建2个虚机，本例中创建1个，另一个直接clone即可，虚机的网卡与系统网桥br0桥接：
# virsh list
Id Name State
----------------------------------------------------
7 centos7 running
8 centos7-clone running
# virsh domiflist centos7
InterfaceType Source Model MAC
-------------------------------------------------------
vnet0 bridge br0 e1000 52:54:00:1c:c8:92
# virsh domiflist centos7-clone
InterfaceType Source Model MAC
-------------------------------------------------------
vnet1 bridge br0 e1000 52:54:00:ee:71:75
在dhcp server 的配置文件中主要包含下列内容：
# cat /etc/dhcp/dhcpd.conf
#
# DHCP Server Configuration file.
# see /usr/share/doc/dhcp*/dhcpd.conf.example
# see dhcpd.conf(5) man page
#
#ddns-uptate-style interim;
#ignore client-updates;
filename "pxelinux.0"; //pxe的引导镜像文件
next-server 192.168.56.2;
subnet 192.168.56.0 netmask 255.255.255.0 {
option routers 192.168.56.2;
option subnet-mask 255.255.255.0;
range dynamic-bootp 192.168.56.150 192.168.56.200;
default-lease-time 21600;
}
需要将pxelinux.0镜像文件放到tftp server的目录中，该文件可以从系统光盘镜像或者系统中获得，同时还有内核文件、引导文件：
# ls /var/lib/tftpboot/
boot.msginitrd.imgpxelinux.0pxelinux.cfgvesamenu.c32vmlinuz
将CentOS7光盘复制到/var/www/html的mnt目录中:
# ls mnt
CentOS_BuildTagEFIEULAGPLimagesisolinuxLiveOSPackagesrepodataRPM-GPG-KEY-CentOS-7RPM-GPG-KEY-CentOS-Testing-7TRANS.TBL
需要配置pxelinux.cfg目录下的default文件，已指示系统通过pxe加载镜像后进一步的动作，这里我们关注的是CentOS7标签，通过http方式结合kickstart自应答文件进行网络自动安装：
# cat default
defaultCentOS7
#default vesamenu.c32
prompt 0
timeout 300
ontimeout local
display boot.msg
F1 boot.msg
F2 options.msg
F3 general.msg
F4 param.msg
F5 rescue.msg
# Clear the screen when exiting the menu, instead of leaving the menu displayed.
# For vesamenu, this means the graphical background is still displayed without
# the menu itself for as long as the screen remains in graphics mode.
menu clear
menu background splash.png
menu title CentOS 7
menu vshift 8
menu rows 18
menu margin 8
menu hidden
menu helpmsgrow 15
menu tabmsgrow 13
# Border Area
menu color border * #00000000 #00000000 none
# Selected item
menu color sel 0 #ffffffff #00000000 none
# Title bar
menu color title 0 #ff7ba3d0 #00000000 none
# Press message
menu color tabmsg 0 #ff3a6496 #00000000 none
# Unselected menu item
menu color unsel 0 #84b8ffff #00000000 none
# Selected hotkey
menu color hotsel 0 #84b8ffff #00000000 none
# Unselected hotkey
menu color hotkey 0 #ffffffff #00000000 none
# Help text
menu color help 0 #ffffffff #00000000 none
# A scrollbar of some type? Not sure.
menu color scrollbar 0 #ffffffff #ff355594 none
# Timeout msg
menu color timeout 0 #ffffffff #00000000 none
menu color timeout_msg 0 #ffffffff #00000000 none
# Command prompt text
menu color cmdmark 0 #84b8ffff #00000000 none
menu color cmdline 0 #ffffffff #00000000 none
# Do not display the actual menu unless the user presses a key. All that is displayed is a timeout message.
menu tabmsg Press Tab for full configuration options on menu items.
menu separator # insert an empty line
menu separator # insert an empty line
labelCentOS7
kernel vmlinuz
append initrd=initrd.img ks=http://192.168.56.2/ks.cfgvga=normal devfs=nomount ramdisk_size=9216 nofb
KS自应答文件可以通过system-config-kickstart工具生成，也可以复制系统中的anaconda目录中的样例，编辑生成：
KVM虚机PXE方式自动安装示例-2629585-2
本例中的ks应答文件主要配置了http网络安装的路径，以及root密码、硬盘分区、以及安装的基本软件包。
# cat /var/www/html/ks.cfg
#platform=x86, AMD64, or Intel EM64T
#version=DEVEL
# Install OS instead of upgrade
install
# Keyboard layouts
keyboard 'us'
# Root password
rootpw --iscrypted $1$2g8RzvvY$YqlnUGED1Js5RAjnchHKK1
# Use network installation
url --url="http://192.168.56.2/mnt/"
# System language
lang en_US
# Firewall configuration
firewall --disabled
# System authorization information
auth--useshadow--passalgo=sha512
# Use graphical install
graphical
firstboot --disable
# SELinux configuration
selinux --disabled
# Network information
network--bootproto=dhcp --device=eth0
# Reboot after installation
reboot
# System timezone
timezone Africa/Abidjan
# System bootloader configuration
bootloader--location=mbr
# Clear the Master Boot Record
zerombr
# Partition clearing information
clearpart --all --initlabel
# Disk partitioning information
part /boot --asprimary --fstype="ext3" --ondisk=sda--size=200
part swap --fstype="swap" --ondisk=sda --size=1024
part / --fstype="ext3" --ondisk=sda --size=16384
%packages
@base
%end
在KVM中启动2个VM，虚机在启动的时候通过DHCP获得IP，同时活得PXE Server地址及启动镜像：
KVM虚机PXE方式自动安装示例-2629585-3
经过pxe引导过程后，开始加载配置文件中的linux内核及引导镜像：
KVM虚机PXE方式自动安装示例-2629585-4
内核与引导镜像加载完毕后，会进一步根据ks应道文件的指示通过http方式进行网络安装，可以看到root密码、硬盘分区、软件包安装都是根据应答文件中相应项目自动进行的，整个安装过程无需人工干预。
KVM虚机PXE方式自动安装示例-2629585-5
安装过程结束后系统会根据自应答文件指示自动重启，系统就安装完毕了，最后附两个截图，图1为DHCP应答中关于next-server和file的；图2为PXE-kickstart 无人值守安装流程图。
KVM虚机PXE方式自动安装示例-2629585-6
KVM虚机PXE方式自动安装示例-2629585-7
谢谢。
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