keepalived,nginx作HA

一，準備工做
1：準備2臺機器，分別安裝上Java、Tomcat、Nginx、Ipvs和Keepalived
2：規劃：
(1)虛擬ip用192.168.1.77
(2)Master機器的ip：192.168.1.106 , Nginx端口80，Tomcat端口8080
(3)Backup機器的ip：192.168.1.201 ，Nginx端口80，Tomcat端口8080
n 配置Nginx，Nginx對兩臺機器的Tomcat作負載均衡
n 配置Keepalived
1：master配置，示例以下：
global_defs {
notification_email { cc@cc.com }
notification_email_from cc@cc.com
smtp_server smtp.cc.com
smtp_connect_timeout 30
router_id nginx_master
}

vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 101
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.77
}
}
2：Backup的配置，示例以下：
global_defs {
notification_email { cc@cc.com }
notification_email_from cc@cc.com
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id cc_backeup
}

vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.77
}
}
3：運行後能夠經過以下命令查看
watch ipvsadm -lc：查看IPVS的鏈接狀況
也可用以下命令查看：ipvsadm -Lc

讓Keepalived監控Nginx的狀態
當NginX中止服務的時候可以自動切換，從而實現服務的高可用性。
1：這個就須要shell腳原本處理，示例以下：
NGINX=/usr/common/nginx/sbin/nginx
PORT=80
nmap localhost -p $PORT | grep "$PORT/tcp open"
#echo $?
if [ $? -ne 0 ];then
$NGINX -s stop
$NGINX
sleep 3
nmap localhost -p $PORT | grep "$PORT/tcp open"
[ $? -ne 0 ] && cd /usr/common/keepalived/sbin && pkill keepalived
echo "over"
fi
注意：要對這個腳本文件設置權限，如：chmod 777 checkNginx.sh

2：而後在keepalived.conf中添加對對腳本的調用
（1）在VRRP服務器配置前，增長：
vrrp_script chk_http_port {
script "/usr/common/keepalived/etc/keepalived/checkNginx.sh"
interval 2
weight 2
}
（2）在vrrp_instance配置裏面的最後部分，添加：
track_script {
chk_http_port
}

Keepalived用作HA
Keepalived用作HA的時候，和具體的應用或服務是沒有關係的，相似於前
面學習的Keepalived+Nginx，一樣能夠實現：
1：Keepalived + Varnish
2：Keepalived + Tomcat
3：Keepalived + Redis
4：Keepalived + MySql
5：Keepalived + ……任意的其餘服務或應用