1.环境说明
2.安装tomcat
在192.168.60.204，192.168.60.205上安装tomcat，并修改 /usr/local/tomcat/webapps/ROOT/index.jsp页面，在页面中加入tomcat的IP地址，例如192.168.60.204上我们修改为：
vim /usr/local/tomcat/webapps/ROOT/index.jsp
${pageContext.servletContext.serverInfo}(192.168.60.204)<%=request.getHeader("X-NGINX")%>
启动204和205两台机器的tomcat，确认浏览器能正确访问http://192.168.60.204:8080和http://192.168.60.205:8080
并且页面上能正确显示各自的IP地址，此时request header里没有X-NGINX，所以显示null。
3.安装nginx
在192.168.60.202 ，192.168.60.203 上都要安装nginx服务，例如192.168.60.202安装过程如下：
安装依赖包
#yum -y install epel-release lrzsz zip unzip wget tree git dpkg pcre pcre-devel openssl openssl-devel gd-devel zlib-devel gcc
#wget http://nginx.org/download/nginx-1.18.0.tar.gz -O /data
#tar -xf nginx-1.18.0.tar.gz
#cd nginx-1.18.0/
#./configure --prefix=/data/nginx --with-http_ssl_module --with-http_v2_module --with-http_stub_status_module --with-pcre --with-http_gzip_static_module --with-http_dav_module --with-http_addition_module --with-http_sub_module --with-http_flv_module --with-http_mp4_module
#make && make install
#/data/nginx/sbin/nginx
#ps -ef |grep nginx
加入开机自启动
#chmod +x /etc/rc.d/rc.local
# vim /etc/rc.d/rc.local
/data/nginx/sbin/nginx浏览器中访问http://192.168.60.202
看到如下界面，则nginx配置成功
4.配置nginx反向代理
在/data/nginx/conf/nginx.conf配置nginx的反向代理，将请求转发到103和104两台tomcat上
在Master（202）中设置proxy_set_header X-NGINX “NGINX-1”
upstream tomcat_server {
server 192.168.60.204:8080 weight=1;
server 192.168.60.205:8080 weight=1;
}
server {
listen 80;
server_name 192.168.60.202;
charset utf-8;
# access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm index.jsp;
proxy_pass http://tomcat_server;
proxy_set_header X-NGINX "NGINX-1";
}在Backup（203）中设置proxy_set_header X-NGINX “NGINX-2”
upstream tomcat_server {
server 192.168.60.204:8080 weight=1;
server 192.168.60.205:8080 weight=1;
}
server {
listen 80;
server_name 192.168.60.203;
charset utf-8;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm index.jsp;
proxy_pass http://tomcat_server;
proxy_set_header X-NGINX "NGINX-2";
}按照上面方法在Master（202）上安装和配置好nginx，浏览器地址栏输入http://192.168.60.202
多次刷新页面，能看到页面上显式IP地址信息，192.168.60.204和192.168.60.205交替显式，说明nginx已经将用户请求负载均衡到了2台tomcat上
并且能看到NGINX-1也能显示在页面上，如下图
同理在Backup（203）上安装和配置好nginx，浏览器地址栏输入http://192.168.60.203
多次刷新页面，能看到页面上显式IP地址信息，192.168.60.204和192.168.60.205交替显式，说明nginx已经将用户请求负载均衡到了2台tomcat上
并且能看到NGINX-2也能显示在页面上，如下图
5.安装Keepalived
yum -y install keepalived
systemctl start keepalived.service
systemctl enable keepalived.service
ps -ef |grep keepalived在/etc/keepalived目录下，添加nginx_check.sh（检查nginx存活的shell脚本）和keepalived.conf（keepalived配置文件）
vim nginx_check.sh
A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];then
systemctl stop keepalived
fiMaster（202）中的keepalived.conf配置如下
修改之前先备份下 cp keepalived.conf{,.bak}
global_defs {
router_id NodeA
}
vrrp_script chk_nginx {
script "/etc/keepalived/nginx_check.sh" //检测nginx进程的脚本
interval 2
weight -20
}
vrrp_instance VI_1 {
state MASTER //主服务器
interface eth0
virtual_router_id 50
mcast_src_ip 192.168.60.202
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.60.220 //虚拟ip
}
}Backup（203）中的keepalived.conf配置如下
global_defs {
router_id NodeA
}
vrrp_script chk_nginx {
script "/etc/keepalived/nginx_check.sh" //检测nginx进程的脚本
interval 2
weight -20
}
vrrp_instance VI_1 {
state BACKUP //从服务器
interface eth0
virtual_router_id 50
mcast_src_ip 192.168.60.203
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
track_script {
chk_nginx
}
virtual_ipaddress {
192.168.60.220 //虚拟ip
}
}关于keepalived配置的几点说明
state - 主服务器需配成MASTER，从服务器需配成BACKUP
interface - 这个是网卡名
mcast_src_ip - 配置各自的实际IP地址
priority - 主服务器的优先级必须比从服务器的高，这里主服务器配置成100，从服务器配置成99
virtual_ipaddress - 配置虚拟IP（192.168.60.220）
authentication - auth_pass主从服务器必须一致，keepalived靠这个来通信
virtual_router_id - 主从服务器必须保持一致
Master，Backup都正常，只有Master对外提供服务
查看keepalived和nginx进程，确保keepalived和nginx启动正常
[```
root@master ~]# ps -ef |grep keepalived
root 4798 1 0 14:26 ? 00:00:00 /usr/sbin/keepalived -D
root 4799 4798 0 14:26 ? 00:00:00 /usr/sbin/keepalived -D
root 4800 4798 0 14:26 ? 00:00:11 /usr/sbin/keepalived -D
root 36110 1509 0 17:51 pts/0 00:00:00 grep --color=auto keepalived
[root@master ~]# ps -ef |grep nginx
root 4770 1 0 14:26 ? 00:00:00 nginx: master process nginx
nobody 32491 4770 0 17:28 ? 00:00:00 nginx: worker process
nobody 32492 4770 0 17:28 ? 00:00:00 nginx: worker process
root 36297 1509 0 17:53 pts/0 00:00:00 grep --color=auto nginx
使用ip add命令，查看VIP是否被绑定到202机器上，可以看到192.168.60.220已经被绑定到202机器上了
[root@master ~]# ip addr
1: lo: 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: eth0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:5e:b0:c5 brd ff:ff:ff:ff:ff:ff
inet 192.168.60.202/22 brd 192.168.63.255 scope global noprefixroute eth0
valid_lft forever preferred_lft forever
inet 192.168.60.220/32 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5221:c926:ed9:826/64 scope link noprefixroute
valid_lft forever preferred_lft forever
再启动Backup（203）机器的keepalived和nginx，确保其正常启动，查看Backup的IP信息，发现VIP现在还没有绑定到Backup（203）上。 [root@slve ~]# ip addr
1: lo:
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: eth0:
link/ether 00:0c:29:bf:ab:7f brd ff:ff:ff:ff:ff:ff
inet 192.168.60.203/22 brd 192.168.63.255 scope global noprefixroute eth0
valid_lft forever preferred_lft forever
inet6 fe80::6538:4b94:1249:2af8/64 scope link noprefixroute
valid_lft forever preferred_lft forever
# 6.验证高可用性
当Master（202）nginx挂了，Backup接替Master对外提供服务
接着，我们在Master（202）机器上停掉nginx服务来模拟Master服务器挂掉，并查看VIP是否还在Master机器上[root@master ~]# nginx -s stop
[root@master ~]# ps -ef |grep nginx
root 37172 1509 0 17:59 pts/0 00:00:00 grep --color=auto nginx
[root@master ~]# ip addr
1: lo:
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: eth0:
link/ether 00:0c:29:5e:b0:c5 brd ff:ff:ff:ff:ff:ff
inet 192.168.60.202/22 brd 192.168.63.255 scope global noprefixroute eth0
valid_lft forever preferred_lft forever
inet6 fe80::5221:c926:ed9:826/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: docker0:
link/ether 02:42:c8:f0:d5:63 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
[root@master ~]#
查看Backup（203）的VIP，发现VIP已经绑定到了Backup（203）[root@slve ~]# ip addr
1: lo:
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: eth0:
link/ether 00:0c:29:bf:ab:7f brd ff:ff:ff:ff:ff:ff
inet 192.168.60.203/22 brd 192.168.63.255 scope global noprefixroute eth0
valid_lft forever preferred_lft forever
inet 192.168.60.220/32 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::6538:4b94:1249:2af8/64 scope link noprefixroute
valid_lft forever preferred_lft forever
浏览器多次刷新并访问http://192.168.60.203/
可以看到页面上IP交替显式204和205，并且显示NGINX-2，则表明是Backup（203）在转发web请求，也就是说Master挂掉后，Backup继续接管Master的服务。
Master恢复正常后，Master继续提供服务，Backup停止服务，并继续等待Master出现故障
我们再启动Master（202）机器的keepalived和nginx，查看VIP，发现VIP已经被Master“夺回”了使用权限
浏览器多次刷新并访问http://192.168.60.202/
可以看到页面上IP交替显式204和205，并且显示NGINX-1，则表明是Master（202）在转发web请求，也就是说Master重新启动后，Master重新对外提供服务，Backup则停止服务继续等待Master挂掉。[root@master ~]# /data/nginx/sbin/nginx
[root@master ~]# ps -ef |grep nginx
root 37200 1 0 18:05 ? 00:00:00 nginx: master process /data/nginx/sbin/nginx
nobody 37201 37200 0 18:05 ? 00:00:00 nginx: worker process
nobody 37202 37200 0 18:05 ? 00:00:00 nginx: worker process
root 37205 1509 0 18:05 pts/0 00:00:00 grep --color=auto nginx
[root@master ~]# systemctl start keepalived.service
[root@master ~]# ps -ef |grep keepalived
root 37230 1 0 18:05 ? 00:00:00 /usr/sbin/keepalived -D
root 37231 37230 0 18:05 ? 00:00:00 /usr/sbin/keepalived -D
root 37232 37230 0 18:05 ? 00:00:00 /usr/sbin/keepalived -D
root 37307 1509 0 18:06 pts/0 00:00:00 grep --color=auto keepalived
[root@master ~]# ip addr
1: lo:
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: eth0:
link/ether 00:0c:29:5e:b0:c5 brd ff:ff:ff:ff:ff:ff
inet 192.168.60.202/22 brd 192.168.63.255 scope global noprefixroute eth0
valid_lft forever preferred_lft forever
inet 192.168.60.220/32 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5221:c926:ed9:826/64 scope link noprefixroute
valid_lft forever preferred_lft forever
到此nginx高可用性已经成功实现，当Master（202）机器nginx挂掉，Backup （203）继续对外提供服务。