最近，公司要我部署一个集群架构，选来选取还是选择了大家都很熟悉的基于DR的LVS+Keepalived做负载分发，然后使用轻量级的nginx做中间代理层，这里呢先暂时实现一个简单web应用功能，对于代理功能和后续的web层部署、数据层安排将择机更新！
首先看一下集群框架：
下面开始我们的集群搭建行程：
一、IP规划：
做一件事情需要想想怎么去做既简单又有条理，我们做项目也应该如此。所以这里一定先做一个简单的规划，对于你后续测试的时候出现不能分发的情况有所解决。
负载均衡层 代理层 WEB层（待定）
LVS1：10.124.20.248 nginx1:10.124.20.250 web1
nginx2:10.124.20.251
LVS2：10.124.20.249 nginx3:10.124.20.252 web2
VIP：10.124.20.20 对应绑定的外网IP：117.78.3.253
备注：在云端虚拟机做架构，比在自己本地虚拟机做实验，要略有不同。初次接触云端虚拟机的同学可能有点犯迷糊，不知道这个ip地址是怎么分配的，怎么去管理。我的老师教给一个最能解决问题的办法：在任何服务之前，首先要了解整个网络环境，然后根据环境部署服务，更改配置、规则等。关于云端虚拟机，它在整个硬件防火墙和整个路由器封闭起来的一个大的局域网集群（这里为了好理解我们姑且认为云端就一个防火墙和一个路由器）。在这个集群中，又有很多网段的局域网，每个企业在申请虚拟机的时候一般会建立一个虚拟机组，这个机组则对应着一个网段。
这里使用的网段是10.124.20.0/24，给各台服务器分配唯一的IP地址。这里要特别说明一下，华为云技术人员建议使用的服务器固定ip在32-254之间，在2-31之间的IP地址作为候补之用，比如说VIP就选用这里面，还有临时加虚拟机的话也可以选用。所以对于IP地址的规划是很重要的。另外说一下，这也是在生产环境中的经验吧，VIP必须是和集群IP地址在一个网段，还要必须有别于集群IP地址，另外要提供网站访问服务或者测试，则需要将内网的VIP与一个公网IP进行绑定，在外部网络浏览器访问外网IP就会直接映射到内网VIP上，然后就会实现我们所熟悉的功能，VIP漂移，LVS分发。小技巧：公网IP与单纯的一个内网ip做绑定是不成功的，所以先把需要绑定公网IP的内网IP绑定到一个虚拟机上，然后再进行绑定，绑定完之后再进行更改IP地址。（比如说我要使用10.124.20.20做VIP，首先我把10.124.20.20绑定到一台虚拟机上，通过后台将外网IP117.78.3.253与10.124.20.20绑定，也就是做映射，最后再将10.124.20.20与虚拟解绑，这样就实现了预期目的）
二、源码安装&&配置
1.LVS+Keepalived搭建
1）LVS1：10.124.20.248&&LVS2：10.124.20.249
cd /usr/local/src/
tar xf ipvsadm-1.24.tar.gz
tar xf keepalived-1.1.20.tar.gz
ipvsadm编译安装
ln -s /usr/src/kernels/2.6.32-279.el6.x86_64/ /usr/src/linux #创建软连接
cd /usr/local/src/ipvsadm-1.24
make && make install
#/sbin/ipvsadm -v #检测ipvsadm是否安装成功(或者：#watch ipvsadm –ln)
ipvsadm v1.24 2005/12/10 (compiled with getopt_long and IPVS v1.2.1)
将ipvsadm设置成开机自启动服务
chkconfig --add keepalived
chkconfig keepalived on
Keepalived编译安装
/usr/local/src/keepalived-1.1.20
./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64
返回信息：
Keepalived configuration
------------------------
Keepalived version : 1.1.20
Compiler : gcc
Compiler flags : -g -O2
Extra Lib : -lpopt -lssl -lcrypto
Use IPVS Framework : Yes
IPVS sync daemon support : Yes
Use VRRP Framework : Yes
Use Debug flags : No
make && make install
返回信息：
install -d /usr/local/keepalived/bin
install -m 755 ../bin/genhash /usr/local/keepalived/bin/
install -d /usr/local/keepalived/share/man/man1
install -m 644 ../doc/man/man1/genhash.1 /usr/local/keepalived/share/man/man1
将Keepalived做成服务：
cd /usr/local/keepalived/
cp etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived
cp etc/keepalived/keepalived.conf /etc/keepalived/
cp sbin/keepalived /usr/sbin/
2） 修改Keepalived.conf配置文件
#cat /etc/keepalived/keepalived.conf #主LVS1：10.124.20.248
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
# smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_sync_group VGM {
group {
VI_1
}
notify_master "/opt/shell/arp.sh"
notify_backup "/opt/shell/arp.sh"
}
vrrp_script chk_nginx {
script "/opt/shell/check_nginx.sh"
interval 1
weight -2
}
vrrp_script chk_nginx2 {
script "/opt/shell/check_nginx2.sh"
interval 1
weight -2
}
vrrp_script chk_nginx3 {
script "/opt/shell/check_nginx3.sh"
interval 1
weight -2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass yzkjTest
}
track_script {
chk_nginx
chk_nginx2
chk_nginx3
}
virtual_ipaddress {
10.124.20.20
}
}
virtual_server 10.124.20.20 80 {
delay_loop 5
lb_algo sh
lb_kind DR
persistence_timeout 60
protocol TCP
real_server 10.124.20.250 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.124.20.251 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.124.20.252 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
#cat /etc/keepalived/keepalived.conf #备LVS1：10.124.20.249
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
# smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_sync_group VGM {
group {
VI_1
}
notify_master "/opt/shell/arp.sh"
notify_backup "/opt/shell/arp.sh"
}
vrrp_script chk_nginx {
script "/opt/shell/check_nginx.sh"
interval 1
weight -2
}
vrrp_script chk_nginx2 {
script "/opt/shell/check_nginx2.sh"
interval 1
weight -2
}
vrrp_script chk_nginx3 {
script "/opt/shell/check_nginx3.sh"
interval 1
weight -2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass yzkjTest
}
track_script {
chk_nginx
chk_nginx2
chk_nginx3
}
virtual_ipaddress {
10.124.20.20
}
}
virtual_server 10.124.20.20 80 {
delay_loop 5
lb_algo sh
lb_kind DR
persistence_timeout 60
protocol TCP
real_server 10.124.20.250 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.124.20.251 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.124.20.252 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
==============================================================
相关检测脚本：
#cat /opt/shell/arp.sh
#!/bin/bash
VIP=10.124.20.20
GATEWAY=10.124.20.1
/sbin/arping -I eth0 -c 5 -s $VIP $GATEWAY &>/dev/null
#cat /opt/shell/check_nginx.sh
!/bin/bash
url="http://10.124.20.250"
status=$(/usr/bin/curl -s --head "$url" | awk ‘/HTTP/ {print $2}‘)
if [ "$status" != "200" ]; then
/opt/shell/arp.sh start
fi
#cat /opt/shell/check_nginx2.sh
!/bin/bash
url="http://10.124.20.251"
status=$(/usr/bin/curl -s --head "$url" | awk ‘/HTTP/ {print $2}‘)
if [ "$status" != "200" ]; then
/opt/shell/arp.sh start
fi
#cat /opt/shell/check_nginx3.sh
!/bin/bash
url="http://10.124.20.252"
status=$(/usr/bin/curl -s --head "$url" | awk ‘/HTTP/ {print $2}‘)
if [ "$status" != "200" ]; then
/opt/shell/arp.sh start
fi
===============================================================
3）Keepalived服务启动（ifconfig eth0:1 10.124.20.248 netmask 255.255.255.255 up）
service keepalived start #服务启动
#ps -aux|grep keepalived #检测服务启动状态
（/usr/local/keepalived/sbin/keepalived -D -f /etc/keepalived/keepalived.conf -D 显示在日志记录 -f 指定配置文件目录）
Warning: bad syntax, perhaps a bogus ‘-‘? See /usr/share/doc/procps-3.2.8/FAQ
root 21205 0.0 0.0 36776 732 ? Ss 17:06 0:00 keepalived -D
root 21207 0.0 0.1 38880 1936 ? S 17:06 0:00 keepalived -D
root 21208 0.0 0.1 38880 1232 ? S 17:06 0:00 keepalived -D
root 21301 0.0 0.0 103240 840 pts/0 S+ 17:07 0:00 grep keepalived
4）#设置开机启动服务
（##echo “/usr/local/keepalived/sbin/keepalived -D -f /etc/keepalived/keepalived.conf” >> /etc/rc.d/rc.local）
chkconfig --add keepalived
chkconfig keepalived on
service iptables stop
5）添加防火墙规则：
iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT #使80端口提供对外服务
iptables -A INPUT -d 224.0.0.0/8 -j ACCEPT
iptables -A INPUT -p vrrp -j ACCEPT #基于DR模式，当用户发出请求后，只有DR响应ARP广播包，允许vrrp虚拟路由器冗余协议
/etc/rc.d/init.d/iptables save #保存规则到iptables文件，使重启后生效）
6）开启转发功能；
#vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
#sysctl -p #使转发能够生效
三、nginx服务器的搭建
1）安装pcre-8.36.tar.gz
cd /usr/local/src
tar xf pcre-8.36.tar.gz
cd pcre-8.36
./configure --prefix=/usr/local/pcre
make && make install
2）安装nginx-1.5.1.tar.gz
cd /usr/local/src
tar xf nginx-1.5.1.tar.gz
cd nginx-1.5.1
./configure --prefix=/usr/local/nginx --with-http_ssl_module --with-http_stub_status_module --with-pcre=/usr/local/src/pcre-8.36 --with-openssl=/usr/local/src/openssl-1.0.0c //这里跟的目录是源码目录，而不是源码安装后的目录
make && make install
3）启动
编写启动脚本:
===============================================================
vim /etc/init.d/nginx | chmod +x /etc/init.d/nginx
#!/bin/sh
#
# nginx - this script starts and stops the nginx daemin
#
# chkconfig: - 85 15
# description: Nginx is an HTTP(S) server, HTTP(S) reverse \
# proxy and IMAP/POP3 proxy server
# processname: nginx
# config: /usr/local/nginx/conf/nginx.conf
# pidfile: /usr/local/nginx/logs/nginx.pid
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ "$NETWORKING" = "no" ] && exit 0
nginx="/usr/local/nginx/sbin/nginx"
prog=$(basename $nginx)
NGINX_CONF_FILE="/usr/local/nginx/conf/nginx.conf"
lockfile=/var/lock/subsys/nginx
start() {
[ -x $nginx ] || exit 5
[ -f $NGINX_CONF_FILE ] || exit 6
echo -n $"Starting $prog: "
daemon $nginx -c $NGINX_CONF_FILE
retval=$?
echo
[ $retval -eq 0 ] && touch $lockfile
return $retval
}
stop() {
echo -n $"Stopping $prog: "
killproc $prog -QUIT
retval=$?
echo
[ $retval -eq 0 ] && rm -f $lockfile
return $retval
}
restart() {
configtest || return $?
stop
start
}
reload() {
configtest || return $?
echo -n $"Reloading $prog: "
killproc $nginx -HUP
RETVAL=$?
echo
}
force_reload() {
restart
}
configtest() {
$nginx -t -c $NGINX_CONF_FILE
}
rh_status() {
status $prog
}
rh_status_q() {
rh_status >/dev/null 2>&1
}
case "$1" in
start)
rh_status_q && exit 0
$1
;;
stop)
rh_status_q || exit 0
$1
;;
restart|configtest)
$1
;;
reload)
rh_status_q || exit 7
$1
;;
force-reload)
force_reload
;;
status)
rh_status
;;
condrestart|try-restart)
rh_status_q || exit 0
;;
*)
echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload|configtest}"
exit 2
esac
======================================================================
service nginx start 启动服务
4）RS配置脚本
======================================================================
#cat /opt/RS.sh
#!/bin/bash
#
# Script to start LVS DR real server.
# description: LVS DR real server
#
. /etc/rc.d/init.d/functions
VIP=10.124.20.20
host=`/bin/hostname`
case "$1" in
start)
# Start LVS-DR real server on this machine.
/sbin/ifconfig lo down
/sbin/ifconfig lo up
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
/sbin/ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up
/sbin/route add -host $VIP dev lo:0
echo "RealServer Start OK"
;;
stop)
# Stop LVS-DR real server loopback device(s).
/sbin/ifconfig lo:0 down
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped OK"
;;
status)
# Status of LVS-DR real server.
islothere=`/sbin/ifconfig lo:0 | grep $VIP`
isrothere=`netstat -rn | grep "lo:0" | grep $VIP`
if [ ! "$islothere" -o ! "isrothere" ];then
# Either the route or the lo:0 device
# not found.
echo "LVS-DR real server Stopped."
else
echo "LVS-DR real server Running."
fi
;;
*)
# Invalid entry.
echo "$0: Usage: $0 {start|status|stop}"
exit 1
;;
esac
===================================================================
启动RS配置：
sh /opt/RS.sh start
四、测试
浏览器访问测试117.78.3.253，能够返回想要的信息即为成功！
五、总结
使用LVS+Keepalived做负载均衡，首先先将内部各个服务器的iptables与selinux关闭，确保内部网络通畅，一般而言，将上述防火墙关闭之后，安装上述配置文件提供的参数进行配置，是能够实现预期功能的。我的文档中可能提到过要设置iptables规则，这个要在测试通过之后，再打开iptables，然后写上防火墙规则。通过查阅很多资料，看到很多人都在防火墙关闭的情况实验成功，看来防火墙与LVS的分发功能是多少有点冲突，对于这方面的知识学习，有待于我们在今后的工作和学习中进行探索，我也将对后续知识在被人博客上做介绍，希望以后能在这个平台与大家一起交流、学习、成长！
[email protected]
2014-12-02