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keepalived
keepalived+lvs实现高可用的负载均衡
测试
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keepalived
keepalived一款轻量级高可用软件，工作于layer3, 4 & 5，不同于前几篇博文中的Heartbeat、Corosync等软件的实现机制不同，它采用虚拟路由冗余协议（Virual Router Redundancy Protocal）来实现并且完美的与lvs结合，由于底层使用虚拟路由冗余协议，因此Keepalived具有切换速度快的特点，工作在layer3的keepalived定期向服务器群组中发送ICMP数据包宣告自己存活与否，工作在layer3的keepalived支持以检测TCP端口状态的方式来判定后台Realserver故障与否，自动并将那些判定为故障的后台Realserver从ipvs规则中踢出，工作在layer5可以支持用户自动以脚本来实现相应的智能操作。此lvs也可以结合ldirectord来实现对后台realserver的动态监测，相对于keepalived来说ldirectord属于重量级别的，部署和使用的灵活程度没有前者方便，本文将介绍keepalived。
keepalived+lvs实现高可用的负载均衡
架构图：
realserver端脚本
#!/bin/bash
#
# Script to start LVS DR real server.
# description: LVS DR real server
#
. /etc/rc.d/init.d/functions
VIP=192.168.1.33
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
;;
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
;;
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
安装httpd并建立测试页面如下：
Director端配置
安装ipvsadm和keepalived
yum install ipvsadm rpm -ivh keepalived-1.2.7-5.el5.i386.rpm
director_master的配置vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost #报警收件人地址
}
notification_email_from root@localhost #报警发件人地址
smtp_server 127.0.0.1 #设置smtp服务地址
smtp_connect_timeout 30 #设置连接smtp服务的超时时间
router_id LVS_DEVEL #发送邮件的主体信息
}
vrrp_script chk_schedown { #自定义脚本
script "[ -e /etc/keepalived/down ] && exit 1 || exit 0"
interval 1 #重试时间间隔
weight -5 #减权重
fall 2
rise 1
}
vrrp_instance VI_1 {
state MASTER #制定keepalived角色
interface eth0 #制定检测网络接口
virtual_router_id 54 #虚拟路由标示码
priority 100 #权重，1-255之间
advert_int 1 #设置同步检查的时间间隔，单位是秒
authentication {
auth_type PASS #验证类型为PASS
auth_pass soulboy #验证密码
}
virtual_ipaddress {
192.168.1.33/24 dev eth0 label eth0:0 #设置虚拟IP
}
track_script {
chk_schedown
}
notify_master "/etc/keepalived/notify.sh -n master -a 192.168.1.33"
notify_backup "/etc/keepalived/notify.sh -n backup -a 192.168.1.33"
notify_fault "/etc/keepalived/notify.sh -n fault -a 192.168.1.33"
}
virtual_server 192.168.1.33 80 { #定义虚拟服务器
delay_loop 6 #设置健康检查时间
lb_algo wrr #设置负载调度算法
lb_kind DR #设置LVS工作模式
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP #设置转发协议的类型
sorry_server 127.0.0.1 80 #设置紧急服务器
real_server 192.168.1.10 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
real_server 192.168.1.20 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
}
}
director_backup的配置vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_schedown {
script "[ -e /etc/keepalived/down ] && exit 1 || exit 0"
interval 1
weight -5
fall 2
rise 1
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 54
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass soulboy
}
virtual_ipaddress {
192.168.1.33/24 dev eth0 label eth0:0
}
track_script {
chk_schedown
}
notify_master "/etc/keepalived/notify.sh -n master -a 192.168.1.33"
notify_backup "/etc/keepalived/notify.sh -n backup -a 192.168.1.33"
notify_fault "/etc/keepalived/notify.sh -n fault -a 192.168.1.33"
}
virtual_server 192.168.1.33 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP
sorry_server 127.0.0.1 80
real_server 192.168.1.10 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
real_server 192.168.1.20 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
}
}
通知脚本vim /etc/keepalived/notify.sh
#!/bin/bash
#
ifalias=${2:-eth0:0}
interface=$(echo $ifalias | awk -F: '{print $1}')
vip=$(ip addr show $interface | grep $ifalias | awk '{print $2}')
contact='root@localhost'
workspace=$(dirname $0)
notify() {
subject="$ip change to $1"
body="$ip change to $1 $(date '+%F %H:%M:%S')"
echo $body | mail -s "$1 transition" $contact
}
case "$1" in
master)
notify master
exit 0
;;
backup)
notify backup
/etc/rc.d/init.d/httpd restart
exit 0
;;
fault)
notify fault
exit 0
;;
*)
echo 'Usage: $(basename $0) {master|backup|fault}'
exit 1
;;
esac
测试
启动director_master的keepalive服务并查看ipvs规则
#####查看ipvs规则
[root@master ~]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.1.33:80 wrr
-> 192.168.1.20:80 Route 1 0 0
-> 192.168.1.10:80 Route 1 0 0
#####查看网络信息
[root@master ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:C2:5E:01
inet addr:192.168.1.61 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fec2:5e01/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:67996 errors:0 dropped:0 overruns:0 frame:0
TX packets:116217 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:15418633 (14.7 MiB) TX bytes:8387202 (7.9 MiB)
Interrupt:67 Base address:0x2024
eth0:0 Link encap:Ethernet HWaddr 00:0C:29:C2:5E:01
inet addr:192.168.1.33 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:67 Base address:0x2024
启动director_backup的keepalive服务并查看ipvs规则
#####查看ipvs规则
[root@backup ~]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.1.33:80 wrr
-> 192.168.1.20:80 Route 1 0 0
-> 192.168.1.10:80 Route 1 0 0
#####查看网络信息
[root@backup ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:FA:52:D6
inet addr:192.168.1.62 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fefa:52d6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:115068 errors:0 dropped:0 overruns:0 frame:0
TX packets:82940 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:19740061 (18.8 MiB) TX bytes:6476242 (6.1 MiB)
Interrupt:67 Base address:0x2024
使用客户端访问VIP
停止director_master的keepalived服务发现VIP消失
[root@master ~]# service keepalived stop
Stopping keepalived: [ OK ]
[root@master ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:C2:5E:01
inet addr:192.168.1.61 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fec2:5e01/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:69371 errors:0 dropped:0 overruns:0 frame:0
TX packets:118587 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:15609985 (14.8 MiB) TX bytes:8588490 (8.1 MiB)
Interrupt:67 Base address:0x2024
在director_backup查看网络信息，发现VIP已成功转移
[root@backup ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:FA:52:D6
inet addr:192.168.1.62 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fefa:52d6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:116816 errors:0 dropped:0 overruns:0 frame:0
TX packets:84293 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:19932196 (19.0 MiB) TX bytes:6597535 (6.2 MiB)
Interrupt:67 Base address:0x2024
eth0:0 Link encap:Ethernet HWaddr 00:0C:29:FA:52:D6
inet addr:192.168.1.33 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:67 Base address:0x2024
停止realserver_one的httpd服务
[root@realserver_one ~]# service httpd stop Stopping httpd: [ OK ]
director_backup查看ipvs规则，发现realserver_one已经被踢出
[root@backup ~]# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.33:80 wrr -> 192.168.1.20:80 Route 1 0 0
客户端访问VIP发现页面恒为node2
停止realserver_two的httpd服务
[root@realserver_two ~]# service httpd stop Stopping httpd: [ OK ]
director_backup查看ipvs规则，发现紧急站点生效
[root@backup ~]# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.33:80 wrr -> 127.0.0.1:80 Local 1 0 0
客户端访问VIP发现页面为自定义警告页面
分别启动realserver_one和realserver_two的httpd服务
#####realserver_one
[root@realserver_one ~]# service httpd start
Starting httpd: httpd: apr_sockaddr_info_get() failed for realserver_one
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
#####realserver_two
[root@realserver_two ~]# service httpd start
Starting httpd: httpd: apr_sockaddr_info_get() failed for realserver_two
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
再次查看director_backup发现ipvs规则已经恢复
[root@backup ~]# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 192.168.1.33:80 wrr -> 192.168.1.20:80 Route 1 0 0 -> 192.168.1.10:80 Route 1 0 0
客户端访问VIP发现负载正常
启动director_master的keepalived服务并查看网络信息发现VIP成功转移
[root@master ~]# service keepalived start
Starting keepalived: [ OK ]
[root@master ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:C2:5E:01
inet addr:192.168.1.61 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fec2:5e01/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:70394 errors:0 dropped:0 overruns:0 frame:0
TX packets:118644 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:15679204 (14.9 MiB) TX bytes:8593207 (8.1 MiB)
Interrupt:67 Base address:0x2024
eth0:0 Link encap:Ethernet HWaddr 00:0C:29:C2:5E:01
inet addr:192.168.1.33 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:67 Base address:0x2024
在director_backup查看网络信息发现VIP消失
[root@backup ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:FA:52:D6
inet addr:192.168.1.62 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fefa:52d6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:118485 errors:0 dropped:0 overruns:0 frame:0
TX packets:87004 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:20112822 (19.1 MiB) TX bytes:6791097 (6.4 MiB)
Interrupt:67 Base address:0x2024
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:6781 errors:0 dropped:0 overruns:0 frame:0
TX packets:6781 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2122280 (2.0 MiB) TX bytes:2122280 (2.0 MiB)