keepalived简介
Keepalived 软件起初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了可以实现高可用的VRRP功能。因此，Keepalived除了能够管理LVS软件外，还可以作为其他服务（例如：Nginx、Haproxy、MySQL等）的高可用解决方案软件。
Keepalived软件主要是通过VRRP协议实现高可用功能的。VRRP是Virtual Router RedundancyProtocol(虚拟路由器冗余协议）的缩写，VRRP出现的目的就是为了解决静态路由单点故障问题的，它能够保证当个别节点宕机时，整个网络可以不间断地运行。
所以，Keepalived 一方面具有配置管理LVS的功能，同时还具有对LVS下面节点进行健康检查的功能，另一方面也可实现系统网络服务的高可用功能。
Keepalived官网：Keepalived for Linux
Keepalived的重要功能
keepalived 有三个重要的功能，分别是：
- 管理LVS负载均衡软件
- 实现LVS集群节点的健康检查
- 作为系统网络服务的高可用性
keepalived好可用故障转移原理
Keepalived 高可用服务之间的故障切换转移，是通过 VRRP (Virtual Router Redundancy Protocol ,虚拟路由器冗余协议）来实现的。
在 Keepalived 服务正常工作时，主 Master 节点会不断地向备节点发送（多播的方式）心跳消息，用以告诉备 Backup 节点自己还活看，当主 Master 节点发生故障时，就无法发送心跳消息，备节点也就因此无法继续检测到来自主 Master 节点的心跳了，于是调用自身的接管程序，接管主 Master 节点的 IP 资源及服务。而当主 Master 节点恢复时，备 Backup 节点又会释放主节点故障时自身接管的IP资源及服务，恢复到原来的备用角色。
原理图
Keepalived高可用对之间是通过VRRP通信的，因此，我们从 VRRP开始了解起：
（1） VRRP,全称 Virtual Router Redundancy Protocol,中文名为虚拟路由冗余协议，VRRP的出现是为了解决静态路由的单点故障。
（2）VRRP是通过一种竟选协议机制来将路由任务交给某台 VRRP路由器的。
（3）VRRP用 IP多播的方式（默认多播地址（224.0.0.18))实现高可用对之间通信。
（4）工作时主节点发包，备节点接包，当备节点接收不到主节点发的数据包的时候，就启动接管程序接管主节点的资源。备节点可以有多个，通过优先级竞选，但一般 Keepalived系统运维工作中都是一对。
（5）VRRP使用了加密协议加密数据，但Keepalived官方目前还是推荐用明文的方式配置认证类型和密码。
再介绍一下 Keepalived服务的工作原理：
Keepalived高可用是通过 VRRP 进行通信的， VRRP是通过竞选机制来确定主备的，主的优先级高于备，因此，工作时主会优先获得所有的资源，备节点处于等待状态，当主挂了的时候，备节点就会接管主节点的资源，然后顶替主节点对外提供服务。
在 Keepalived 服务之间，只有作为主的服务器会一直发送 VRRP 组播包,告诉备它还活着，此时备不会枪占主，当主不可用时，即备监听不到主发送的组播包时，就会启动相关服务接管资源，保证业务的连续性.接管速度最快可以小于1秒。
keepalived部署
四台主机
192.168.100.10 master
192.168.100.10 slave
192.168.100.30 rs1
192.168.100.50 rs2
192.168.100.60 测试访问
rs1和rs2添加好网页[root@rs2 ~]# yum -y install nginx
[root@rs2 ~]# echo rs1 > /usr/share/nginx/html/index.html[root@rs1 ~]# systemctl restart nginx;systemctl enable nginx
[root@rs1 ~]# rs2
[root@rs2 ~]# yum -y install nginx
[root@rs2 ~]# echo rs2 > /usr/share/nginx/html/index.html[root@rs2 ~]# systemctl restart nginx;systemctl enable nginx
[root@rs2 ~]# 测试访问
master，slave主机做负载均衡
master
vim /etc/nginx/nginx.confupstream cc {server 192.168.100.30:80;server 192.168.100.50:80;}server {listen 80;server_name localhost;location / {proxy_pass http://cc;}
slave
vim /etc/nginx/nginx.confupstream cc {server 192.168.100.30:80;server 192.168.100.50:80;}server {listen 80;server_name localhost;location / {proxy_pass http://cc;}
测试访问
master，slave主机都安装keepalived和相关软件包
yum -y install gcc gcc-c++
yum -y install keepalived
查看keepalived配置文件
vim /etc/keepalived/keepalived.conf global_defs { //全局配置notification_email { //定义报警收件人邮件地址acassen@firewall.locfailover@firewall.locsysadmin@firewall.loc}notification_email_from Alexandre.Cassen@firewall.loc //定义报警发件人邮箱smtp_server 192.168.200.1 //邮箱服务器地址smtp_connect_timeout 30 //定义邮箱超时时间router_id LVS_DEVEL //定义路由标识信息，同局域网内唯一vrrp_skip_check_adv_addrvrrp_strictvrrp_garp_interval 0vrrp_gna_interval 0
}vrrp_instance VI_1 { //定义实例state MASTER //指定keepalived节点的初始状态，可选值为MASTER/BACKUPinterface eth0 //VRRP实例绑定的网卡接口，用户发送VRRP包virtual_router_id 51 //虚拟路由的ID，同一集群要一致priority 100 //定义优先级，按优先级来决定主备角色，优先级越大越优先advert_int 1 //主备通讯时间间隔authentication { //配置认证auth_type PASS //认证方式，此处为密码auth_pass 1111 //同一集群中的keepalived配置里此处必须一致，推荐使用8为随机数}virtual_ipaddress { //配置要使用的VIP192.168.200.16192.168.200.17192.168.200.18}
}virtual_server 192.168.200.100 443 { //配置虚拟服务器delay_loop 6 //健康检查的时间间隔lb_algo rr //lvs调度算法lb_kind NAT //lvs模式persistence_timeout 50 //持久化超时时间，单位为秒protocol TCP //4层协议sorry_server 192.168.200.200 1358 //定义备用服务器，当所有RS都故障时，用sorry_server来响应客户端real_server 192.168.201.100 443 { //定义真实处理请求的服务器weight 1 //给服务器指定权重，默认为1SSL_GET {url {path / //指定要检查的URL路径digest ff20ad2481f97b1754ef3e12ecd3a9cc //摘要信息}url {path /mrtg/digest 9b3a0c85a887a256d6939da88aabd8cd}connect_timeout 3 //连接超时时间retry 3 //get尝试次数delay_before_retry 3 //在尝试之前延迟多长时间}}
}virtual_server 10.10.10.2 1358 {delay_loop 6lb_algo rrlb_kind NATpersistence_timeout 50protocol TCPsorry_server 192.168.200.200 1358real_server 192.168.200.2 1358 {weight 1HTTP_GET {url {path /testurl/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl2/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl3/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}connect_timeout 3retry 3delay_before_retry 3}}real_server 192.168.200.3 1358 {weight 1HTTP_GET {url {path /testurl/test.jspdigest 640205b7b0fc66c1ea91c463fac6334c}url {path /testurl2/test.jspdigest 640205b7b0fc66c1ea91c463fac6334c}connect_timeout 3retry 3delay_before_retry 3}}
}virtual_server 10.10.10.3 1358 {delay_loop 3lb_algo rrlb_kind NATpersistence_timeout 50protocol TCPreal_server 192.168.200.4 1358 {weight 1HTTP_GET {url {path /testurl/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl2/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl3/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}connect_timeout 3retry 3delay_before_retry 3}}real_server 192.168.200.5 1358 {weight 1HTTP_GET {url {path /testurl/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl2/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}url {path /testurl3/test.jspdigest 640205b7b0fc66c1ea91c463fac6334d}connect_timeout 3retry 3delay_before_retry 3}}
}
修改主keepalived配置文件
vim /etc/keepalived/keepalived.confglobal_defs {router_id cz01
}vrrp_instance VI_1 {state MASTERinterface ens160virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.100.150}
}virtual_server 192.168.100.150 80 {delay_loop 6lb_algo rrlb_kind DRpersistence_timeout 50protocol TCPreal_server 192.168.100.10 80 {weight 1TCP_CHECK {connect_port 80 connect_timeout 3 nb_get_retry 3delay_before_retry 3}}real_server 192.168.100.20 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}
}
配置从keepalived配置文件
vim /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs {router_id cz02
}vrrp_instance VI_1 {state BACKUPinterface ens160virtual_router_id 51priority 50advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.100.150}
}virtual_server 192.168.100.150 80 {delay_loop 6lb_algo rrlb_kind DRpersistence_timeout 50protocol TCPreal_server 192.168.100.10 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}real_server 192.168.100.20 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}
}
修改内核参数，开启侦听VIP功能
此步可做可不做，该功能可用于仅监听VIP的时候
Master和slave：vim /etc/sysctl.conf
net.ipv4.ip_nonlocal_bind = 1sysctl -p
重启服务并设置下次启动生效
[root@master ~]# systemctl restart keepalived.service
[root@master ~]# systemctl enable keepalived.service
此时可以查看ip地址
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope host valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000link/ether 00:0c:29:b8:d7:51 brd ff:ff:ff:ff:ff:ffaltname enp3s0inet 192.168.100.10/24 brd 192.168.100.255 scope global noprefixroute ens160valid_lft forever preferred_lft foreverinet 192.168.100.150/32 scope global ens160valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:feb8:d751/64 scope link noprefixroute valid_lft forever preferred_lft forever此时就不需要去配置虚拟地址了，192.168.100.150就是虚拟地址了slave启动服务
[root@slave ~]# systemctl restart keepalived.service
[root@slave ~]# systemctl enable keepalived.service
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.[root@slave ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope host valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000link/ether 00:0c:29:82:d1:8e brd ff:ff:ff:ff:ff:ffaltname enp3s0inet 192.168.100.20/24 brd 192.168.100.255 scope global noprefixroute ens160valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe82:d18e/64 scope link noprefixroute valid_lft forever preferred_lft forever
[root@slave ~]#
测试，使用虚拟地址来访问
让keepalived监控nginx负载均衡
//在master上编写脚本
[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# vim check.sh
#!/bin/bash
nginx_status=`ps -ef | grep -v "grep" | grep "nginx" | wc -l`
if [ $nginx_status -lt 1 ];thensystemctl stop keepalived
fi
[root@master scripts]# chmod +x check.sh///
[root@master scripts]# vim notify.sh
#!/bin/bash
VIP=$2
sendmail () { subject="${VIP}'s server keepalived state is translate"content="`date +'%F %T'`: `hostname`'s state change to master"echo $content | s-nail -s "$subject" cczz1999@163.com
}
case "$1" inmaster)nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)if [ $nginx_status -lt 1 ];thensystemctl start nginxfisendmail;;backup)nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)if [ $nginx_status -gt 0 ];thensystemctl stop nginxfi;;*)echo "Usage:$0 master|backup VIP";;
esac[root@master scripts]# chmod +x notify.sh
在slave上编写脚本
[root@slave keepalived]# mkdir /scripts
[root@slave keepalived]# cd /scripts/
[root@slave scripts]# scp root@192.168.100.10:/scripts/check.sh .
root@192.168.100.100's password:
check.sh 100% 137 296.3KB/s 00:00
[root@slave scripts]# scp root@192.168.100.10:/scripts/notify.sh .
root@192.168.100.100's password:
notify.sh 100% 594 1.0MB/s 00:00
[root@slave scripts]# chmod +x check.sh
[root@slave scripts]# chmod +x notify.sh
配置master的keepalived
! Configuration File for keepalivedglobal_defs {router_id cz01
}vrrp_script nginx_check {script "/scripts/check.sh"interval 10weight -20
}vrrp_instance VI_1 {state MASTERinterface ens160virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.100.150}track_script {nginx_check}notify_master "/scripts/notify.sh master 192.168.100.150"notify_backup "/scripts/notify.sh backup 192.168.100.150"
}virtual_server 192.168.100.150 80 {delay_loop 6lb_algo rrlb_kind DRpersistence_timeout 50protocol TCPreal_server 192.168.100.10 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}real_server 192.168.100.20 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}
}
配置slave的keepalived
! Configuration File for keepalivedglobal_defs {router_id cz02
}vrrp_instance VI_1 {state BACKUPinterface ens160virtual_router_id 51priority 50advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.100.150}notify_master "/scripts/notify.sh master 192.168.100.150"notify_backup "/scripts/notify.sh backup 192.168.100.150"
}virtual_server 192.168.100.150 80 {delay_loop 6lb_algo rrlb_kind DRpersistence_timeout 50protocol TCPreal_server 192.168.100.10 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}real_server 192.168.100.20 80 {weight 1TCP_CHECK {connect_port 80connect_timeout 3nb_get_retry 3delay_before_retry 3}}
}测试
查看负载均衡是否可用
模拟故障
启用keepalived，开启nginx服务
[root@master scripts]# systemctl restart keepalived.service
[root@master scripts]# systemctl enable keepalived
[root@master scripts]# systemctl restart nginx
[root@master scripts]# systemctl enable nginx关闭master的nginx服务
[root@master scripts]# systemctl stop nginx此时虚拟ip就不在master节点上了
[root@master scripts]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope host valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000link/ether 00:0c:29:b8:d7:51 brd ff:ff:ff:ff:ff:ffaltname enp3s0inet 192.168.100.10/24 brd 192.168.100.255 scope global noprefixroute ens160valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:feb8:d751/64 scope link noprefixroute valid_lft forever preferred_lft forever查看slave节点
[root@slave scripts]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope host valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000link/ether 00:0c:29:82:d1:8e brd ff:ff:ff:ff:ff:ffaltname enp3s0inet 192.168.100.20/24 brd 192.168.100.255 scope global noprefixroute ens160valid_lft forever preferred_lft foreverinet 192.168.100.150/32 scope global ens160valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe82:d18e/64 scope link noprefixroute valid_lft forever preferred_lft forever此时虚拟IP在slave节点运行测试访问
