LVS + keepalived + tomcat负载均衡及高可用实现（初级）
1、首先检测Linux服务器是否支持ipvs
执行如下命令：modprobe -l|grep ipvs
输出：
kernel/net/netfilter/ipvs/ip_vs.ko kernel/net/netfilter/ipvs/ip_vs_rr.ko kernel/net/netfilter/ipvs/ip_vs_wrr.ko kernel/net/netfilter/ipvs/ip_vs_lc.ko kernel/net/netfilter/ipvs/ip_vs_wlc.ko kernel/net/netfilter/ipvs/ip_vs_lblc.ko kernel/net/netfilter/ipvs/ip_vs_lblcr.ko kernel/net/netfilter/ipvs/ip_vs_dh.ko kernel/net/netfilter/ipvs/ip_vs_sh.ko kernel/net/netfilter/ipvs/ip_vs_sed.ko kernel/net/netfilter/ipvs/ip_vs_nq.ko kernel/net/netfilter/ipvs/ip_vs_ftp.ko kernel/net/netfilter/ipvs/ip_vs_pe_sip.ko
表示支持！
否则需要手动下载安装ipvs
2、检查是否已经安装所必须的包
执行如下命令：
rpm -q kernel-devel
rpm -q gcc
rpm -q openssl
rpm -q openssl-devel
rpm -q popt
rpm -q popt-static
rpm -q kernel-headers
输出：package ** is not installed 需要手动安装；
yum命令是安装，更新，删除依赖包的命令；相当于一个软件包管理器；
安装方法：yum install kernel-devel -y
yum install gcc -y
……
3、安装ipvsadm
首先确定安装的版本，安装的版本应该与Linux内核版本一致；
通过：rpm -q kernel-devel 查看内核版本，根据内核版本，下载相对应的ipvsadm；
我的内核版本：kernel-devel-2.6.32-642.3.1.el6.x86_64
对应的ipvsadm版本：ipvsadm-1.26.tar.gz
4、解压
tar -zxvf ipvsadm-1.26.tar.gz
5、建立软连接
ln -s /usr/src/kernels/2.6.32-642.3.1.el6.x86_64 /usr/src/linux
6、编译安装
进入到ipvsadm-1.26下
执行 make && make install
报错可能是依赖的包缺失，需要安装：yum install -y libnl* popt*
至此，安装ipvsadm成功
7、keepalive安装
下载地址：http://www.keepalived.org/software/
解压；
进入到keepalive目录：cd keepalived-1.2.19
执行 ./configure
等待…………
执行 make
等待…………
执行 make install
安装完成。
8、配置主从服务器
进入如下目录： /usr/local/etc/keepalived/ 打开keepalived.conf文件
1 ! Configuration File for keepalived 2 3 global_defs { 4 notification_email { 5 acassen@firewall.loc 6 failover@firewall.loc 7 sysadmin@firewall.loc 8 } 9 notification_email_from Alexandre.Cassen@firewall.loc 10 smtp_server 127.0.0.1 11 smtp_connect_timeout 30 12 router_id LVS_DEVEL 13 } 14 15 vrrp_instance VI_1 { 16 state MASTER 17 interface eth0 18 virtual_router_id 230 19 priority 100 20 advert_int 1 21 authentication { 22 auth_type PASS 23 auth_pass 1111 24 } 25 virtual_ipaddress { 26 192.168.91.230 27 } 28 } 29 30 virtual_server 192.168.91.230 8080 { 31 delay_loop 6 32 lb_algo rr 33 lb_kind DR 34 nat_mask 255.255.255.0 35 persistence_timeout 0 36 protocol TCP 37 38 real_server 192.168.91.231 8080 { 39 weight 1 40 TCP_CHECK { 41 connect_timeout 3 42 nb_get_retry 3 43 delay_before_retry 3 44 connect_port 8080 45 } 46 } 47 real_server 192.168.91.232 8080 { 48 weight 1 49 TCP_CHECK { 50 connect_timeout 3 51 nb_get_retry 3 52 delay_before_retry 3 53 connect_port 8080 54 } 55 } 56 }
! Configuration File for keepalived global_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 230 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.91.230 } } virtual_server 192.168.91.230 8080 { delay_loop 6 lb_algo rr lb_kind DR nat_mask 255.255.255.0 persistence_timeout 0 protocol TCP real_server 192.168.91.231 8080 { weight 1 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 connect_port 8080 } } real_server 192.168.91.232 8080 { weight 1 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 connect_port 8080 } } }
9、配置LVS server客户端
执行如下脚本即可：
#!/bin/bash # description: Config realserver LVS_VIP=192.168.91.230 /etc/rc.d/init.d/functions case "$1" in start) /sbin/ifconfig lo:0 $LVS_VIP netmask 255.255.255.255 broadcast $LVS_VIP /sbin/route add -host $LVS_VIP dev lo:0 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 sysctl -p >/dev/null 2>&1 echo "RealServer Start OK" ;; stop) /sbin/ifconfig lo:0 down /sbin/route del $LVS_VIP >/dev/null 2>&1 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" ;; *) echo "Usage: $0 {start|stop}" exit 1 esac exit 0
10、keepalived的启动
service keepalived start 或者 keepalived -D -f /usr/local/etc/keepalived/keepalived.conf
查看日志：tail -f /var/log/messages
在默认情况下，Keepalived在启动时会查找/etc/Keepalived/Keepalived.conf配置文件
小结：到此为止，当主服务器或者从服务器上的tomcat挂掉之后，不会对客户端产生影响；
上述keepalived健康检测是协议检测，也就是说跟业务无关；
遗留问题:
1、 本机realserver宕掉后，不会切换到从服务器；（已解决，未配置LVS server客户端）
2、 Kill掉keepalived后，另一个不会自动接管VIP（已解决 是防火墙的原因，关闭防火墙即可）
3、 通过ip a命令，查看，两个机器同时占有VIP（已解决 是防火墙的原因，关闭防火墙即可）
同时keepalived kill掉之后，另一个会主动接管虚IP killall keepalived (杀掉keepalive进程 ，kill 与 all之间没有空格)
一些常用命令：
ip a 查看此时VIP是否启用
正常情况，输出：
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet 192.168.91.230/32 brd 192.168.91.230 scope global lo:0 inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:23:ae:9e:0e:20 brd ff:ff:ff:ff:ff:ff inet 192.168.91.231/24 brd 192.168.91.255 scope global eth0 inet 192.168.91.230/32 scope global eth0 inet6 fe80::223:aeff:fe9e:e20/64 scope link valid_lft forever preferred_lft forever
VIP未被此机抢占，输出：
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet 192.168.91.230/32 brd 192.168.91.230 scope global lo:0 inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:23:ae:ae:e4:e8 brd ff:ff:ff:ff:ff:ff inet 192.168.91.232/24 brd 192.168.91.255 scope global eth0 inet6 fe80::223:aeff:feae:e4e8/64 scope link valid_lft forever preferred_lft forever
查看转发路由、转发规则命令：ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.91.230:8080 rr -> 192.168.91.231:8080 Local 1 0 0 -> 192.168.91.232:8080 Route 1 0 0
