linux之keepalived詳解

一、keepalive簡介

Keepalived是專門針對LVS設計的一款強大的輔助工具，主要用來提供故障切換和健檢查功能，如判斷LVS負載調度器、節點服務器的可用性，及時隔離並替換爲新的服務器，當故障主機恢復後將其重新加入羣集。在非LVS羣集環境中使用時Keepalived也可以作爲熱備軟件使用。

Keepalived採用VRRP(virtual router redundancy protocol，虛擬路由冗餘協議)熱備份協議，以軟件的方式實現linux服務器的多機熱備功能。VRRP是針對路由器的一種備份解決方案-----由多臺路由器組成一個熱備組。通過共用的虛擬IP地址對外提供服務；每個熱備組內同一時刻只有一臺主服務器提供服務，其他服務器處於冗餘狀態，若當前在線的服務器失敗，其他服務器會自動接替（優先級決定接替順序）虛擬IP地址，以繼續提供服務。

熱備組內的每臺服務器都可以成爲主服務器，虛擬IP地址（VIP）可以在熱備組內的服務器之間進行轉移，所以也稱爲漂移IP地址，使用Keepalived時，漂移地址的實現不需要手動建立虛擬接口配置文件（如eth0:0），而是由Keepalived根據配置文件自動管理。

二、keepalive原理

keepalived啓動後會有三個進程
父進程：內存管理，子進程管理等等
子進程：VRRP子進程
子進程：healthchecker子進程

有圖可知，兩個子進程都被系統WatchDog看管，兩個子進程各自複雜自己的事，healthchecker子進程複雜檢查各自服務器的健康程度，例如HTTP，LVS等等，如果healthchecker子進程檢查到MASTER上服務不可用了，就會通知本機上的兄弟VRRP子進程，讓他刪除通告，並且去掉虛擬IP，轉換爲BACKUP狀態。

三、部署keepalived服務

環境：Centos6.5-x64位系統

IP:172.16.16.15(master),172.16.16.16(backup)

VIP:172.16.16.100

關閉iptables，selinux

只是演示keepalive的常用配置，因此yum安裝，如有需要，請百度源碼安裝。

[root@localhost ~]# yum install keepalived -y

keepalive主配置文件在/etc/keepalived/下，

1.實現簡單的VIP漂移

master配置文件：

! Configuration File for keepalived

global_defs {

notification_email {

root@localhost ##########收件人郵箱，每行一個收件人

}

notification_email_from keepadmin@localhost #########發件人郵箱，可以不存在

smtp_server 127.0.0.1 ###########郵件服務器地址

smtp_connect_timeout 30 ########郵件服務器連接超時時間

router_id LVS_DEVEL #########服務器的標識

}

vrrp_instance VI_1 { ########熱備實例

state MASTER ########熱備狀態

interface eth0 #########監控心跳，向備發送宣告

virtual_router_id 51 #########虛擬路由id，主備必須一致

priority 100 #########定義優先級，值越大優先級越高

advert_int 1 #########主備宣告的時間間隔，

authentication { #########設置驗證

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

172.16.16.100 ######定義vip，注此機器只有一塊網卡，默認加到eth0上，若多塊網卡，或者子卡，可以設置爲172.16.16.100 dev eth1[label eth0:0]等指定設備

}

backup配置文件：

! Configuration File for keepalived

global_defs {

notification_email {

root@localhost

}

notification_email_from keepadmin@localhost

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_instance VI_1 {

state BACKUP ###修改此節點爲備

interface eth0

virtual_router_id 51

priority 99 ########優先級要比主低

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

172.16.16.100

}

啓動兩個幾點keepalived

master：

root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

inet 172.16.16.100/32 scope global eth0

inet6 fe80::20c:29ff:fec2:ccff/64 scope link

valid_lft forever preferred_lft forever

backup

[root@localhost keepalived]# ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

inet6 fe80::20c:29ff:fe5c:ef24/64 scope link

valid_lft forever preferred_lft forever

關閉master的keepalive,

master

[root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

inet6 fe80::20c:29ff:fec2:ccff/64 scope link

valid_lft forever preferred_lft forever

backup

[root@localhost keepalived]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

inet6 ::1/128 scope host

valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

inet 172.16.16.100/32 scope global eth0 #######vip漂移到backup

inet6 fe80::20c:29ff:fe5c:ef24/64 scope link

valid_lft forever preferred_lft forever

2.定義簡單的腳本命令

在/etc/keepalived/目錄下，檢測到down文件，vip漂移

master/backup

global_defs {

notification_email {

root@localhost

}

notification_email_from keepadmin@localhost

smtp_server 127.0.0.1

! Configuration File for keepalived

global_defs {

notification_email {

root@localhost

}

notification_email_from keepadmin@localhost

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_maintainace { #######定義檢測腳本參數vrrp_script，chk_maintainace自定義

script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0" ##可以爲腳本，或命令

interval 1 ######檢測down文件的時間間隔爲1秒

weight -2 ########檢測到down文件，優先級-2（即100-2）

}

vrrp_instance VI_1 {

state MASTER/BACKUP

interface eth0

virtual_router_id 51

priority 100/99

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

172.16.16.100

}

track_script {

chk_maintainace ############追蹤腳本

}

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

inet 172.16.16.100/32 scope global eth0

inet6 fe80::20c:29ff:fec2:ccff/64 scope link

valid_lft forever preferred_lft forever

[root@localhost keepalived]# touch down

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

inet6 fe80::20c:29ff:fec2:ccff/64 scope link ######vip漂移

valid_lft forever preferred_lft forever

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:5c:ef:24 brd ff:ff:ff:ff:ff:ff

inet 172.16.16.16/16 brd 172.16.255.255 scope global eth0

inet 172.16.16.100/32 scope global eth0 ######vip漂移到backup

inet6 fe80::20c:29ff:fe5c:ef24/64 scope link

valid_lft forever preferred_lft forever

[root@localhost keepalived]# rm -rf down 主刪除down

[root@localhost keepalived]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:c2:cc:ff brd ff:ff:ff:ff:ff:ff

inet 172.16.16.15/16 brd 172.16.255.255 scope global eth0

inet 172.16.16.100/32 scope global eth0 ######vip漂移回master

inet6 fe80::20c:29ff:fec2:ccff/64 scope link

valid_lft forever preferred_lft forever

3.當主從切換時，實現郵件通知（運行腳本）

腳本notify.sh，在終端運行沒問題，在測試。

#!/bin/bash

IP=`ifconfig eth0 | awk /'inet addr'/'{print $2}' | awk -F : '{print $2}'`

vip='172.16.16.100'

send='root@localhost'

notify(){

subject="$IP to be $1"

body="`date +%F` : $IP become $1"

echo $body | mail -s "$subject" $send

}

case "$1" in

master)

notify master

exit 0;;

backup)

notify backup

exit 0;;

fault)

notify fault

exit 0;;

echo "Usage: `basename $0` (master|backup|fault)";;

esac

master/backup

global_defs {

notification_email {

root@localhost

}

notification_email_from keepadmin@localhost

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_maintainace {

script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"

interval 1

weight -2

}

vrrp_instance VI_1 {

state MASTER/BACKUP

interface eth0

virtual_router_id 51

priority 100/99

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

172.16.16.100

}

track_script {

chk_maintainace

}

notify_master "/etc/keepalived/notify.sh master" #######當切到主時，調用腳本

notify_backup "/etc/keepalived/notify.sh backup" #######當切到從時，調用腳本

notify_fault "/etc/keepalived/notify.sh fault" #######當故障時，調用腳本

}

4.配置ipvs

環境：Centos6.5_64

MASTER:172.16.16.15,BACKUP:172.16.16.16

VIP:172.16.16.100

WEB1:172.16.16.101 WEB2:172.16.16.102

關閉iptables，selinux

軟件包均採用源碼安裝：

master/backup

[root@localhost keepalived]# yum install ipvsadm keepalived -y

master/backup配置文件

[root@localhost keepalived]# cat keepalived.conf

! Configuration File for keepalived

global_defs {

notification_email { ######設置收件人

[email protected]

}

notification_email_from [email protected]

smtp_server 192.168.200.1 #######設置發件人

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_instance VI_1 {

state MASTER/BACKUP ###熱備狀態

interface eth0 #####心跳宣告的接口

virtual_router_id 51 ######虛擬路由器id，必須與backup一樣

priority 100/99 ###優先級

advert_int 1 ##宣告間隔

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

172.16.16.100 ####vip

}

virtual_server 172.16.16.100 80 { ###配置lvs負載均衡

delay_loop 6 ###每隔6秒，檢查一次realserver監控狀態

lb_algo rr #####算法

lb_kind DR ######負載均衡機制

persistence_timeout 10 ######同一IP的連接n秒內被分配到同一臺realserver

protocol TCP #######用TCP協議檢查realserver狀態

real_server 172.16.16.101 80 { #######第一realserver，web節點

weight 1 ####幾點權重

TCP_CHECK { ##########健康檢查方式

connect_port 80

connect_timeout 3 #####3秒連接不上，即爲故障

nb_get_retry 3 ######重試次數

delay_before_retry 4 ###重試間隔

}

real_server 172.16.16.102 80 {

weight 1

TCP_CHECK {

connect_port 80

connect_timeout 3

nb_get_retry 3

delay_before_retry 4

}

注：realserver健康檢查有多種，如SSL_TCP，SSL_GET等

後臺web配置，http提供web，web配置一樣

[root@localhost html]# yum install httpd -y

echo 'web1/2' >> /var/www/html/index.html

調整內核ARP響應，避免MAC衝突（web1/web2）

[root@localhost keepalived]# cat /etc/sysctl.conf

net.ipv4.conf.all.arp_ignore = 1

net.ipv4.conf.all.arp_announce = 2

net.ipv4.conf.default.arp_ignore = 1

net.ipv4.conf.default.arp_announce = 2

net.ipv4.conf.lo.arp_ignore = 1

net.ipv4.conf.lo.arp_announce = 2

配置lo:0網卡

[root@localhost network-scripts]# cat ifcfg-lo:0

DEVICE=lo:0

IPADDR=172.16.16.100 #########VIP

NETMASK=255.255.255.255

ONBOOT=yes

啓動服務

MASTER/BACKUP

/etc/init.d/keepalived restart

WEB

/etc/init.d/httpd restart

測試：訪問172.16.16.100，分別訪問到web1/web2，配置成功

5、配置雙主模型

master/backup配置

global_defs {

notification_email {

[email protected]

}

notification_email_from [email protected]

smtp_server 192.168.200.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_instance VI_1 { ###主一標識

state MASTER/BACKUP

interface eth0

virtual_router_id 51 ########主一虛擬路由標識

priority 100/99 ##優先級

advert_int 1

authentication {

auth_type PASS

auth_pass 1111 #####主一驗證

}

virtual_ipaddress {

172.16.16.100 ###主一vip

}

vrrp_instance VI_2 { ###主二標識

state BACKUP/MASTER

interface eth0

virtual_router_id 50 ########主二虛擬路由標識

priority 49/50 ##優先級

advert_int 1

authentication {

auth_type PASS

auth_pass 2222 #####主二驗證

}

virtual_ipaddress {

172.16.16.200 ###主二vip

}

參考：

http://blog.csdn.net/jibcy/article/details/7826158詳細的keepalive配置文件講解

http://bbs.nanjimao.com/thread-845-1-1.html

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