Nginx+Keepalived双主架构实现

Keepalived+Nginx实现高可用Web负载均衡

Master 192.168.0.69 nginx、keepalived Centos7.4
backup 192.168.0.70 nginx、keepalived Centos7.4
vip（虚拟IP）
192.168.0.180

1、两台都安装nginx，参照安装nginx文档

2、 两台都安装Keepalived

yum install -y libnl libnl-devel libnfnetlink-devel popt-devel

cd /usr/local/src/

tar -zxvf keepalived-1.2.18.tar.gz

cd keepalived-1.2.18

./configure --prefix=/usr/local/keepalived

make && make install

3、将keepalived安装成Linux系统服务

mkdir /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/sbin/keepalived /usr/sbin/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/
ln -s /usr/local/keepalived/sbin/keepalived /usr/local/sbin/
chkconfig keepalived on

4、修改keepalived配置文件

接下来就是配置了，很简单，之前的删除，直接复制下面配置文件

先是主服务器：

vi /etc/keepalived/keepalived.conf

global_defs
{
notification_email #通知email，根据实际情况配置
{
admin@example.com
}
notification_email_from admin@example.com
smtp_server 127.0.0.1
stmp_connect_timeout 30
router_id node1 #节点名标识，主要用于通知中
}

vrrp_script chk_http_port {
script "/usr/local/keepalived/nginx.sh" #在这里添加脚本链接
interval 3 #脚本执行间隔
weight 2 #脚本结果导致的优先级变更
　　}

vrrp_instance VI_NODE_1 {
state MASTER #配置为主服务器
interface ens33 #通讯网卡
virtual_router_id 100 #路由标识
priority 200 #优先级，0-254
advert_int 5 #通知间隔，实际部署时可以设置小一点，减少延时

authentication {
auth_type PASS
auth_pass 123456 #验证密码，用于通讯主机间验证
　　}

track_script {
chk_http_port #添加脚本执行
　　}

virtual_ipaddress {
192.168.0.180 #虚拟ip，可以定义多个
　　}
}

vrrp_instance VI_NODE_2 {
state MASTER #配置为主服务器
interface ens33 #通讯网卡
virtual_router_id 101 #路由标识
priority 100 #优先级，0-254
advert_int 5 #通知间隔，实际部署时可以设置小一点，减少延时

authentication {
auth_type PASS
auth_pass 123456 #验证密码，用于通讯主机间验证
}

track_script {
chk_http_port #添加脚本执行
}

virtual_ipaddress {
192.168.0.181 #虚拟ip，可以定义多个
}
}

接下是从服务器设置：

vi /etc/keepalived/keepalived.conf

global_defs {
notification_email {
admin@example.com
}
notification_email_from admin@example.com
smtp_server 127.0.0.1
stmp_connect_timeout 30

router_id node2
}

vrrp_script chk_http_port {
script "/usr/local/keepalived/nginx.sh" #在这里添加脚本链接
interval 3 #脚本执行间隔
weight 2 #脚本结果导致的优先级变更
}

vrrp_instance VI_NODE_1 {
state BACKUP #与主服务器对应
interface ens33 #从服务器的通信网卡
virtual_router_id 100 #路由标识，和主服务器相同
priority 100 #优先级，小于主服务器即可
advert_int 5 #这里是接受通知间隔，与主服务器要设置相同

authentication {
auth_type PASS
auth_pass 123456 #验证密码，与主服务器相同
}

track_script {
chk_http_port #添加脚本执行
}

virtual_ipaddress {
192.168.0.180 #虚拟IP，也要和主服务器相同
}
}

vrrp_instance VI_NODE_2 {
state BACKUP #与主服务器对应
interface ens33 #从服务器的通信网卡
virtual_router_id 101 #路由标识，和主服务器相同
priority 100 #优先级，小于主服务器即可
advert_int 5 #这里是接受通知间隔，与主服务器要设置相同

authentication {
auth_type PASS
auth_pass 123456 #验证密码，与主服务器相同
}

track_script {
chk_http_port #添加脚本执行
}

virtual_ipaddress {
192.168.0.181 #虚拟IP，也要和主服务器相同
}
}

5 两个节点配置check_ngixn脚本

当脚本检测到nginx没有运行的时候会尝试去启动nginx以此，如果失败则停掉keepalived进程

vi /usr/local/keepalived/nginx.sh

#!/bin/bash
A=`ps -C nginx –no-header |wc -l`
if [ $A -eq 0 ];then
/usr/local/nginx/sbin/nginx #nginx命令的路径
sleep 3
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
fi
fi

6、启动keepalived
[root@bogon ~]# service keepalived start
Starting keepalived (via systemctl): [ OK ]

7、查看虚拟ip在哪台上, 注意过两分钟才出现vip

[root@bogon ~]# ip a
[root@bogon ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:24:21:c4 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.69/24 brd 192.168.0.255 scope global noprefixroute ens33
valid_lft forever preferred_lft forever
inet 192.168.0.180/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.0.181/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::d675:3ae7:5113:ad71/64 scope link noprefixroute
valid_lft forever preferred_lft forever

8、我们修改两个nginx的首页信息，在首页中加入各自的IP地址

vi /usr/local/nginx/html/index.html

<h1>Welcome to nginx! 192.168.0.69</h1>

9、访问：http://192.168.0.180/ http://192.168.0.181/

Welcome to nginx! 192.168.0.69

If you see this page, the nginx web server is successfully installed and working. Further configuration is required.

For online documentation and support please refer to nginx.org.
Commercial support is available at nginx.com.

Thank you for using nginx.

10、高可用切换

在192.168.0.69停止keepalived ， 查看192.168.0.180飘到了192.168.0.70上

service keepalived stop

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:ba:67:74 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.70/24 brd 192.168.0.255 scope global noprefixroute ens33
valid_lft forever preferred_lft forever
inet 192.168.0.180/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::6c33:a5d6:2ea9:d781/64 scope link noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::d675:3ae7:5113:ad71/64 scope link tentative noprefixroute dadfailed
valid_lft forever preferred_lft forever

报错解决

1、
[root@bogon keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived

*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS

yum -y install libnl libnl-devel

2、

configure: error: libnfnetlink headers missing

yum install -y libnfnetlink-devel

3、

安装keepalived出错./configure: error: Popt libraries is required

yum? -y? install? popt-devel

4、

[root@bogon keepalived-1.2.8]# /etc/rc.d/init.d/keepalived start
Starting keepalived (via systemctl): Job for keepalived.service failed because the control process exited with error code. See "systemctl status keepalived.service" and "journalctl -xe" for details.
[FAILED]

[root@bogon keepalived-1.2.8]# ln -s /usr/local/keepalived/sbin/keepalived /usr/bin/
[root@bogon keepalived-1.2.8]# /etc/init.d/keepalived start
Starting keepalived (via systemctl): [ OK ]

参考：   https://www.jianshu.com/p/da26df4f7d60