LVS+keepalived 實現負載均衡
一、資源規劃
在開始搭建之前，我們首先需要準備和規劃好搭建所需的資源。因為效能等方面的考慮，我們使用當前比較流行的DR模式。
搭建前我們需要了解，搭建環境的機器必須在同一網段內，此次環境搭建需要1個VIP和四臺機器（我這裡使用四臺VM）
具體清單如下：
|
伺服器 |
IP地址 |
作業系統 |
閘道器 |
虛擬裝置名 |
VIP |
部署 |
|
Master Director |
30.16.252.190 |
Red Hat Enterprise 6.7 (Santiago) |
30.16.252.128 |
eth0:0 |
30.16.252.240 |
Lvs+keepalived |
|
Backup Director |
30.16.252.191 |
Red Hat Enterprise 6.7 (Santiago) |
30.16.252.128 |
eth0:0 |
30.16.252.240 |
Lvs+keepalived |
|
Real Server |
30.16.252.188 |
Red Hat Enterprise 6.7 (Santiago) |
30.16.252.128 |
lo:0 |
30.16.252.240 |
tomcat |
|
Real Server |
30.16.252.189 |
Red Hat Enterprise 6.7 (Santiago) |
30.16.252.128 |
lo:0 |
30.16.252.240 |
tomcat |
二、配置real server
在/usr/local/sbin下新建realserver.sh，並修改許可權為可執行。
在配置的過程中，需要注意VIP的掩碼需要配置成32位
下面的配置用來在real server上啟用一個VIP，並讓這個VIP忽略網路中的ARP請求。
#realserver.sh
=========================================================================
#!/bin/sh
RS_VIP=30.16.252.240
sh /etc/rc.d/init.d/functions
case "$1" in
start)
ifconfig lo:0 $RS_VIP netmask 255.255.255.255 broadcast $RS_VIP
/sbin/route add -host $RS_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)
ifconfig lo:0 down
route del $RS_VIP >/dev/null2>&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
===========================================================================
配置完後，執行：sh realserver.sh start
需要配置開機自啟動：echo "/usr/local/sbin/realserver.sh start" >> /etc/rc.local
兩臺real server的配置是相同的，都要啟動。
搭建應用：
在兩臺real server上部署tomcat，並新建應用test，在test下新建index.html
#index.html
[30.16.252.188:8080] #根據兩臺機器真實值填寫。
三、安裝keepalived
1. 我們選擇keepalived的版本為1.2.8. 具體安裝步驟如下：
cd /usr/local
tar -zxvf keepalived-1.2.8.tar.gz
cd keepalived-1.2.8
#在執行下面命令前請先做檢查
#如果沒有這個目錄：/usr/src/kernels/2.6.32-642.6.2.el6.x86_64，可執行命令：yum install kernel-headers kernel-devel
#如果沒有/usr/src/linux這個目錄，可以執行命令：ln -s /usr/src/kernels/2.6.32-642.6.2.el6.x86_64 /usr/src/linux
#2.6.32-642.6.2.el6.x86_64為系統核心版本號，大家機器上的目錄可能都不同，執行命令時，以機器上真實的值為準。
./configure --sysconf=/etc --with-kernel-dir=/usr/src/linux
make && make install
ln -s /usr/local/sbin/keepalived /sbin/keepalived
#中間任何一步有報錯都是缺少依賴包造成，我們需要安裝：
yum install libnl* libpopt*
yum install popt-devel popt-static
yum install libnfnetlink libnfnetlink-devel
然後編譯和安裝就會通過。
2. 修改配置檔案
keepalived的配置檔案位置：/etc/keepalived/keepalived.conf
30.16.252.190 Master的配置如下：
============================================================================
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 163
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
30.16.252.240
}
}
virtual_server 30.16.252.240 8080 {
delay_loop 2
lb_algo rr
lb_kind DR
#persistence_timeout50
protocol TCP
real_server 30.16.252.188 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 30.16.252.189 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
=============================================================================
30.16.252.191Backup的配置如下：
=============================================================================
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 163
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
30.16.252.240
}
}
virtual_server 30.16.252.240 8080 {
delay_loop 2
lb_algo rr
lb_kind DR
#persistence_timeout50
protocol TCP
real_server 30.16.252.188 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 30.16.252.189 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
=============================================================================
3. 啟動keepalived
service keepalived start
啟動日誌可檢視：/var/log/message
===========================================================================================================
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Netlink reflector reports IP 30.16.252.190added
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Netlink reflector reports IPfe80::455:4ff:fe00:43ae added
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Registering Kernel netlink reflector
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Registering Kernel netlink command channel
Mar 2 10:31:44 SZC-L0051222Keepalived_vrrp[305580]: Opening file '/etc/keepalived/keepalived.conf'.
Mar 2 10:31:44 SZC-L0051222Keepalived_vrrp[305580]: Configuration is using : 60678 Bytes
Mar 2 10:31:44 SZC-L0051222Keepalived_vrrp[305580]: Using LinkWatch kernel netlink reflector...
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Opening file'/etc/keepalived/keepalived.conf'.
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Configuration is using : 18337 Bytes
Mar 2 10:31:44 SZC-L0051222Keepalived_vrrp[305580]: VRRP sockpool: [ifindex(2), proto(112), unicast(0),fd(10,11)]
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Using LinkWatch kernel netlink reflector...
Mar 2 10:31:44 SZC-L0051222 Keepalived_healthcheckers[305578]: Activatinghealthchecker for service [30.16.252.188]:8080 #檢測要負載的real server的健康狀況
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Activating healthchecker for service[30.16.252.189]:8080
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Activating healthchecker for service[30.16.252.188]:8088
Mar 2 10:31:44 SZC-L0051222Keepalived_healthcheckers[305578]: Activating healthchecker for service[30.16.252.189]:8088
Mar 2 10:31:45 SZC-L0051222 Keepalived_vrrp[305580]: VRRP_Instance(VI_1)Transition to MASTER STATE #keepalived direcotor server 之間通訊
Mar 2 10:31:46SZC-L0051222 Keepalived_vrrp[305580]: VRRP_Instance(VI_1) Entering MASTER STATE
Mar 2 10:31:46 SZC-L0051222Keepalived_vrrp[305580]: VRRP_Instance(VI_1) setting protocol VIPs.
Mar 2 10:31:46 SZC-L0051222Keepalived_vrrp[305580]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0for 30.16.252.240
Mar 2 10:31:46 SZC-L0051222Keepalived_healthcheckers[305578]: Netlink reflector reports IP 30.16.252.240added
Mar 2 10:31:51 SZC-L0051222Keepalived_vrrp[305580]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0for 30.16.252.240
==============================================================================================================================
四、負載驗證
因在Director server上不能訪問對外提供的VIP，所以又在同網段找了一臺機器進行驗證。
因為防火牆等原因，不能直接使用browser來進行驗證，所以就寫了程式，因為使用了rr(輪詢演算法)，所以1000次訪問，兩臺server各訪問500次。
注意：persistence_timeout配置可以進行會話保持，即同一臺機器在設定的時間內，請求會定向到同一臺real server.
驗證正常。