keepalived集群高可用
keepalived是基于vrrp的实现，最初为ipvs提供高可用功能，同时能够检测后端realserver的健康状态，此后又为其他的服务提供高可用功能，它可以调用外部脚本，监控资源状态，从而进行故障转移，比较适用于节点比较少，不使用共享存储等情况下；相对于heartbeat以及corosync和RHCS来说，算是一种轻量级的高可用解决方案。keepalived包含2个主要组件，一个组件负责VRRP协议的实现和管理，一个负责对资源进行监控；运行VRRP的主机在主机之间发送组播信息，用以通告自身的优先级、以及其他属性，主机的优先级范围从0-255, 0表示不参与选举，255表示最高优先级，优先级高的会成为MASTER，在MASTER上启动VIP和VMAC，所有发送到VIP的数据包，由MASTER进行处理，当MASTER出现故障或资源出现问题，会停止发送心跳信息或降低自身优先级，当BACKUP主机发现自己的优先级高于对方或检测不到对方时，会将自己提升为MASTER，当原先的MASTER恢复时，默认可以把MASTER抢回去，可以配置不抢占。
在CentOS 6.4上有keepalived的rpm包，直接安装就可以
# yum -yinstall keepalivedInstalled:keepalived.x86_64 0:1.2.7-3.el6
Dependency Installed:lm_sensors-libs.x86_64 0:3.1.1-17.el6 net-snmp-libs.x86_64 1:5.5-44.el6
配置文件在/etc/keepalived/keepalived.conf，服务启动脚本是/etc/init.d/keepalived
#cat keepalived.conf! Configuration File forkeepalived
global_defs {notification_email {acassen@firewall.loc用以定义状态切换时邮件通知对象，可写多行（个）}notification_email_fromAlexandre.Cassen@firewall.loc；发件人smtp_server 192.168.200.1 SMTP服务器地址smtp_connect_timeout 30连接超时时长router_id LVS_DEVEL VRRP主机标识
vrrp_scriptchk_state_down {script "[[ -f /etc/keepalived/down ]]"自定义一个检测条件，如果存在此文件interval 1检测间隔为1sweight -10 weight 减去10；}
}
vrrp_instanceVI_1 {定义一个VRRP实例state MASTER状态为MASTERinterface eth0在eth0上监听VIPvirtual_router_id 10 定义所属的组，同一个组中的主机必须相同；priority 100优先级advert_int 1通告间隔（advertising interval）authentication {认证auth_type PASS类型auth_pass 1111密码}virtual_ipaddress {172.16.1.250 定义VIP}
track_script {chk_state_down}
}
virtual_server172.16.1.10080 {delay_loop 6lb_algo rrlb_kind NATnat_mask 255.255.255.0persistence_timeout 50protocol TCP
real_server 172.16.1.2 80 {weight 1HTTP_GET {检测后端realserver的方式为GETurl {path /state_code 200 检测报文头部的状态码为200}connect_timeout 3检测超时时间为3snb_get_retry 3重试的次数为3次delay_before_retry 3重试的间隔}}}
定义主机发生状态变化时，发送邮件通知首先定义一个脚本：#!/bin/bash#vip=172.16.1.100contact='root@localhost'notify (){mailsubject="`hostname` became to $1 , $vip floated."mailbody="`date +"%F %T"`: vrrp status changed.`hostname` became $1"echo $mailbody | mail -s "$mailsubject" $contact}
case $1inmaster)notify master ;;backup)notify backup;;fault)notify fault ;;*)echo "Usage: `basename $0` {master|backup|fault}"exit 1;;esac
编辑配置文件：vrrp_instance Instance1 {state MASTERinterface eth0virtual_router_id 10priority 100advert_int 1authentication {auth_type PASSauth_pass 1119}virtual_ipaddress {172.16.1.100}track_script {chk_state_down}notify_master"/etc/keepalived/nofity.sh master"notify_backup"/etc/keepalived/nofity.sh backup"notify_fault"/etc/keepalived/nofity.sh fault"}
#cat keepalived.conf! Configuration File forkeepalived
global_defs {notification_email {root@localhost}notification_email_from admin@163.comsmtp_server 127.0.0.1smtp_connect_timeout 30router_id Node4.magedu.com}
vrrp_scriptchk_state_down {script "[[ -f /etc/keepalived/down]] && exit 1 || exit 0"interval 1weight -10}
vrrp_instance Instance1 {state MASTERinterface eth0virtual_router_id 10priority 100advert_int 1authentication {auth_type PASSauth_pass 1119}virtual_ipaddress {172.16.1.100}track_script {chk_state_down}notify_master"/etc/keepalived/notify.sh master"notify_backup"/etc/keepalived/notify.sh backup"notify_fault"/etc/keepalived/notify.sh fault"}
virtual_server172.16.1.100 80 {delay_loop 6lb_algo rrlb_kind NATnat_mask 255.255.255.0persistence_timeout 50protocol TCP
real_server 172.16.1.3 80 {weight 1HTTP_GET {url {path /state_code 200}connect_timeout 3nb_get_retry 3delay_before_retry 3}}real_server 172.16.1.2 80 {weight 1HTTP_GET {url {path /status_code 200}connect_timeout 3nb_get_retry 3delay_before_retry 3}}}}
如果检测成功就会自动生成ipvs规则#ipvsadm -L -nIP Virtual Server version1.2.1 (size=4096)Prot LocalAddress:PortScheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP 172.16.1.100:80 rr persistent 50-> 172.16.1.2:80 Masq 1 0 0-> 172.16.1.3:80 Masq 1 0 0当有一个real server失效以后，会自动修改规则：#ipvsadm -L -nIP Virtual Server version1.2.1 (size=4096)Prot LocalAddress:PortScheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP 172.16.1.100:80 rr persistent 50-> 172.16.1.3:80 Masq 1 0 0#tail /var/log/messagesSep 25 04:22:20 node5Keepalived_vrrp: VRRP_Instance(Instance1) Sending gratuitous ARPs oneth0 for 172.16.1.100Sep 25 04:22:25 node5Keepalived_vrrp: VRRP_Instance(Instance1) Sending gratuitous ARPs oneth0 for 172.16.1.100Sep 25 04:22:28 node5Keepalived_vrrp: VRRP_Instance(Instance1) Received higher prio advertSep 25 04:22:28 node5Keepalived_vrrp: VRRP_Instance(Instance1) Entering BACKUP STATESep 25 04:22:28 node5Keepalived_vrrp: VRRP_Instance(Instance1) removing protocol VIPs.Sep 25 04:22:28 node5Keepalived_healthcheckers: Netlink reflector reports IP 172.16.1.100removedSep 25 04:36:11 node5Keepalived_healthcheckers: Error connecting server :80.Sep 25 04:36:11 node5Keepalived_healthcheckers: Removing service :80 from VS:80Sep 25 04:36:11 node5Keepalived_healthcheckers: Remote SMTP server :25 connected.Sep 25 04:36:11 node5Keepalived_healthcheckers: SMTP alert successfully sent.
# 如何对特定的服务实现高可用：思路：让vrrp_script 监控程序的运行状态，当服务停止时，降低优先级，优先级降低引起VRRP的状态切换，切换的同时，系统会发出邮件，管理员收到邮件后及时处理故障，启动服务后，优先级恢复到原来的值，根据实际情况配置preempt；如果不对故障进行处理那么当第二台设备也服务也停止了，整个系统将无法工作；# cat keepalived.conf!Configuration File for keepalived
global_defs {notification_email {root@localhost}notification_email_from admin@163.comsmtp_server 127.0.0.1smtp_connect_timeout 30router_id Node4.magedu.com}
vrrp_script chk_state_down {script"[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"interval 1weight-2}vrrp_script chk_httpd {script"killall -0 httpd"interval 1fall 2rise 1weight-20}
vrrp_instanceInstance1 {state MASTERinterface eth0virtual_router_id 10priority 100advert_int 1authentication {auth_type PASSauth_pass 1119}virtual_ipaddress {172.16.1.100}track_script {chk_state_downchk_httpd}notify_master "/etc/keepalived/notify.sh master"notify_backup "/etc/keepalived/notify.sh backup"notify_fault "/etc/keepalived/notify.sh fault"
}# cat notify.sh#!/bin/bashvip=172.16.1.100contact='root@localhost'notify () {mailsubject="`hostname` became to$1 , $vip floated."mailbody="`date +"%F%T"`: vrrp status changed. `hostname` became $1"echo $mailbody | mail -s"$mailsubject" $contact}
case $1 inmaster)notify master/etc/init.d/httpd start;;backup)notify backup/etc/init.d/httpd stop;;fault)notify fault/etc/init.d/httpd stop;;*)echo "Usage: `basename $0`{master|backup|fault}"exit 1;;
esac
keepalived双主模型：提供2个vrrp实例，2个vip；
vrrp_instance Instance1 {state MASTERinterface eth0virtual_router_id 10priority 100advert_int 1authentication {auth_type PASSauth_pass 1119}virtual_ipaddress {172.16.1.100}track_script {chk_state_downchk_httpd}notify_master"/etc/keepalived/notify.sh master"notify_backup"/etc/keepalived/notify.sh backup"notify_fault"/etc/keepalived/notify.sh fault"
}
vrrp_instance Instance2 {state BACKUPinterface eth0virtual_router_id 20priority 95advert_int 1authentication {auth_type PASSauth_pass 2119}virtual_ipaddress {172.16.1.101}track_script {chk_state_downchk_httpd}notify_master"/etc/keepalived/notify.sh master"notify_backup"/etc/keepalived/notify.sh backup"notify_fault"/etc/keepalived/notify.sh fault"
}重启keepalived服务# servicekeepalived restart#ip addr show1: lo:<LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWNlink/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00inet 127.0.0.1/8 scope host loinet6 ::1/128 scope hostvalid_lft forever preferred_lft forever2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000link/ether 00:0c:29:85:22:ac brdff:ff:ff:ff:ff:ffinet 172.16.1.4/16 brd 172.16.255.255 scopeglobal eth0inet 172.16.1.100/32 scope global eth0inet6 fe80::20c:29ff:fe85:22ac/64 scopelinkvalid_lft forever preferred_lft forever
当另一台主机发生故障时：#ip addr show1: lo:<LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWNlink/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00inet 127.0.0.1/8 scope host loinet6 ::1/128 scope hostvalid_lft forever preferred_lft forever2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000link/ether 00:0c:29:85:22:ac brdff:ff:ff:ff:ff:ffinet 172.16.1.4/16 brd 172.16.255.255 scopeglobal eth0inet 172.16.1.100/32 scope global eth0inet 172.16.1.101/32 scope global eth0inet6 fe80::20c:29ff:fe85:22ac/64 scopelinkvalid_lft forever preferred_lft forever
怀揣两块，胸怀500万！ 走，MM，咱们化蝶去…… 不知该说些什么。。。。。。就是谢谢 我抢、我抢、我抢沙发~ 鸳鸳相抱何时了，鸯在一边看热闹。 相当不错，感谢无私分享精神！
页:
[1]