在某种强大力量的推动下，写了人生中第一篇博文，主要是最近学习了一些集群知识，然后当做是做一下笔记。前端用nginx反向代理加上keepalived，两台nginx代理服务器做的是双主双备，代理到后端的两台web服务器，实现一个简单的集群吧。拓扑图如下：
centos1（nginx反向代理服务器）：192.168.40.145
centos2（nginx反向代理服务器）：192.168.40.146
centosA（后端web服务器）：192.168.40.12
centosB（后端web服务器）：192.168.40.19
vip：192.168.40.100
192.168.40.200
首先是centos1的nginx反向代理的设置：
nginx的反向代理就是指将Internet的访问送达到内网服务器，然后将得到的结果返回给Internet连接的客户端，对外就表现成一个服务器。
更改nginx的配置文件，/usr/local/nginx/conf/nginx.conf
先更改upstream模块，upstream模块就是它通过请求后端服务器得到内容而不是自己产生内容。Upstream能够使nginx实现网络数据接收，处理和转发。
http {.
.
.
upstream web_up{
server 192.168.40.12:80 max_fails=3 fail_timeout=20s weight=2;
server 192.168.40.19:80 max_fails=3 fail_timeout=20s weight=2;
}
server {
.
.
.
}
}
server添加两台后端服务器，分别是192.168.40.12:80和192.168.40.19:80，然后是max_fails=3，最大错误连接次数为3次，超过就直接剔除该服务器。fail_timeout=20s，连接错误时间是20s，weight=2权重为2。
接下来是server板块：
server {listen 80;server_name localhost;#charset koi8-r;#access_log logs/host.access.log main;location / {proxy_pass http://web_up; ##对应上面upstream定义的web_upproxy_store off; ##启用本地缓存功能proxy_redirect off; ##指定修改被代理服务器返回的响应头中的location头域跟refresh头域数值proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; ##定义或添加字段传递给代理服务器的请求头。proxy_set_header X-Real-IP $remote_addr;proxy_set_header Host $host;}
然后就跟上面一样的方式去配置另外一台nginx反向代理服务器。
然后都检测一下配置是否有问题：
[root@centos1 ~]# /usr/local/nginx/sbin/nginx -tnginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is oknginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful[root@centos2 ~]# /usr/local/nginx/sbin/nginx -tnginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is oknginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful
检查都没问题后开启nginx：
[root@centos1 ~]# /usr/local/nginx/sbin/nginx[root@centos2 ~]# /usr/local/nginx/sbin/nginx
接下来就要配置keepalived了。
先安装keepalived：
yum install keepalived -y
修改centos1的keepalived的配置文件，这里做的是双主双备。
[root@centos1 ~]# cat /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs {notification_email { ##邮件接受者root@localhost}notification_email_from Alexandre.Cassen@firewall.loc ##邮件发送者smtp_server 127.0.0.1 ##邮件发送地址smtp_connect_timeout 30 ##超时时长}vrrp_script chk_http_port { ##这个部分定义nginx反向代理服务的检测脚本script "/tmp/nginx_check.sh" ##脚本路径interval 2 ##检测周期weight -2 ##如果脚本被执行，那么优先级将会降低2fall 2 ##指监控几次判断为失败rise 1 ##指监控几次判断为成功}vrrp_instance VI_1 {state MASTER ##状态interface ens33 ##心跳网卡virtual_router_id 50 ##两台keepalived的同一个vrrp_instance里面的 id要相同priority 100 ##优先级，优先级高的将拥有vipadvert_int 1 ##间隔时间authentication { ##认证信息。两台keepalived设置成一样的auth_type PASSauth_pass 1111}virtual_ipaddress { ##vip192.168.40.100}track_script {chk_http_port ##指定检测脚本}}vrrp_instance VI_ ##配置第二个vipstate BACKUPinterface ens33virtual_router_id 17priority 99advert_int 1authentication {auth_type PASSauth_pass 2222}virtual_ipaddress {192.168.40.200}track_script {chk_http_port}}
修改centos2的keepalived配置文件：
配置基本一样，就是注意吧优先级改一下。
[root@centos2 tmp]# cat /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs {notification_email {root@localhost}notification_email_from Alexandre.Cassen@firewall.locsmtp_server 127.0.0.1smtp_connect_timeout 30}vrrp_script chk_http_port {script "/tmp/nginx_check.sh"interval 2weight -2fall 2rise 1}vrrp_instance VI_1 {state BACKUPinterface ens33virtual_router_id 50priority 99advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.40.100}track_script {chk_http_port}}vrrp_instance VI_2 {state MASTERinterface ens33virtual_router_id 17priority 100advert_int 1authentication {auth_type PASSauth_pass 2222}virtual_ipaddress {192.168.40.200}track_script {chk_http_port}}
接下来是写一个检测脚本，检测脚本的写法有很多种。这是我的检测脚本,写得有些low：
[root@centos2 tmp]# cat /tmp/nginx_check.sh#!/bin/bashNGINX_PID=/usr/local/nginx/logs/nginx.pidif [ -f $NGINX_PID ]; then netstat -ntlp | grep `cat $NGINX_PID` if [ $? -eq 0 ]; then echo "your nginx is running" else systemctl stop keepalived fielse systemctl stop keepalived echo "your nginx is no running"fi
给它可执行权限：
chmod a+x /tmp/nginx_check.sh
两台keepalived的脚本是一样的。
接下来配置一下两台后端的web服务器：
先安装个nginx服务，这里就不写了。然后把默认主页改一下，为了测试有个好效果。
[root@centosa ~]# cat /usr/local/nginx/html/index.htmlaaa[root@centosb ~]# cat /usr/local/nginx/html/index.htmlbbb
然后都开启web服务：
[root@centosa ~]# /usr/local/nginx/sbin/nginx[root@centosb ~]# /usr/local/nginx/sbin/nginx
接下来回到centos1和centos2，开启keepalived服务：
[root@centos1 ~]# systemctl start keepalived[root@centos2 ~]# systemctl start keepalived
看一下keepalived的状态：
[root@centos1 ~]# systemctl status keepalived● keepalived.service - LVS and VRRP High Availability MonitorLoaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)Active: active (running) since 四 2017-10-19 23:49:14 CST; 3s agoProcess: 15709 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)Main PID: 15710 (keepalived)CGroup: /system.slice/keepalived.service├─15710 /usr/sbin/keepalived -D├─15711 /usr/sbin/keepalived -D└─15712 /usr/sbin/keepalived -D10月 19 23:49:14 centos1 Keepalived_vrrp[15712]: VRRP_Script(chk_http_port) succeeded10月 19 23:49:14 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) Transition to MASTER STATE10月 19 23:49:15 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) Entering MASTER STATE10月 19 23:49:15 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) setting protocol VIPs.10月 19 23:49:15 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:15 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.40.10010月 19 23:49:15 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:15 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:15 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:15 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.100
可以看到本机的主备状态和获取vip的状态。
用ip addr sh命令看一下vip：
[root@centos1 ~]# ip addr sh ens332: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000link/ether 00:0c:29:83:05:b0 brd ff:ff:ff:ff:ff:ffinet 192.168.40.145/24 brd 192.168.40.255 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.100/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::8783:64ef:f718:b05f/64 scope linkvalid_lft forever preferred_lft forever
可以看到是拥有一个192.168.40.100的vip的。
看第二台的keepalived状态：
[root@centos2 ~]# systemctl status keepalived● keepalived.service - LVS and VRRP High Availability MonitorLoaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)Active: active (running) since 四 2017-10-19 23:49:00 CST; 5min agoProcess: 85581 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)Main PID: 85582 (keepalived)CGroup: /system.slice/keepalived.service├─85582 /usr/sbin/keepalived -D├─85583 /usr/sbin/keepalived -D└─85584 /usr/sbin/keepalived -D10月 19 23:49:14 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) setting protocol VIPs.10月 19 23:49:14 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:14 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 9910月 19 23:49:14 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) Entering BACKUP STATE10月 19 23:49:14 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) removing protocol VIPs.
用ip addr sh查看一下vip：
[root@centos2 ~]# ip addr sh ens332: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000link/ether 00:0c:29:18:67:af brd ff:ff:ff:ff:ff:ffinet 192.168.40.146/24 brd 192.168.40.255 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.200/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe18:67af/64 scope linkvalid_lft forever preferred_lft forever
接下来开启一台测试主机来检测一下：
[root@test ~]# curl http://192.168.40.100aaa[root@test ~]# curl http://192.168.40.100bbb[root@test ~]# curl http://192.168.40.100aaa[root@test ~]# curl http://192.168.40.100bbb
先curl第一个vip能看到轮替效果。
访问第二个vip也能有同样的效果。
[root@test ~]# curl http://192.168.40.200aaa[root@test ~]# curl http://192.168.40.200bbb[root@test ~]# curl http://192.168.40.200aaa[root@test ~]# curl http://192.168.40.200bbb
停止centos1的nginx服务：
[root@centos1 ~]# /usr/local/nginx/sbin/nginx -s stop
keepalived也自动停止了。
[root@centos1 ~]# systemctl status keepalived● keepalived.service - LVS and VRRP High Availability MonitorLoaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)Active: inactive (dead)10月 19 23:49:20 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.40.10010月 19 23:49:20 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:20 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:20 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:49:20 centos1 Keepalived_vrrp[15712]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:14 centos1 Keepalived[15710]: Stopping10月 19 23:56:14 centos1 systemd[1]: Stopping LVS and VRRP High Availability Monitor...10月 19 23:56:14 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) sent 0 priority10月 19 23:56:14 centos1 Keepalived_vrrp[15712]: VRRP_Instance(VI_1) removing protocol VIPs.10月 19 23:56:15 centos1 systemd[1]: Stopped LVS and VRRP High Availability Monitor.
然后去到centos2看一下keepalived状态：
[root@centos2 ~]# systemctl status keepalived● keepalived.service - LVS and VRRP High Availability MonitorLoaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)Active: active (running) since 四 2017-10-19 23:49:00 CST; 9min agoProcess: 85581 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)Main PID: 85582 (keepalived)CGroup: /system.slice/keepalived.service├─85582 /usr/sbin/keepalived -D├─85583 /usr/sbin/keepalived -D└─85584 /usr/sbin/keepalived -D10月 19 23:56:15 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:15 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:15 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:15 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 19 23:56:20 centos2 Keepalived_vrrp[85584]: Sending gratuitous ARP on ens33 for 192.168.40.100
查看一下vip：
[root@centos2 ~]# ip addr sh ens332: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000link/ether 00:0c:29:18:67:af brd ff:ff:ff:ff:ff:ffinet 192.168.40.146/24 brd 192.168.40.255 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.200/32 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.100/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe18:67af/64 scope linkvalid_lft forever preferred_lft foreve
可以看到已经拥有两个vip了，接下来再访问一下：
[root@test ~]# curl http://192.168.40.100aaa[root@test ~]# curl http://192.168.40.100bbb[root@test ~]# curl http://192.168.40.200aaa[root@test ~]# curl http://192.168.40.200bbb
可以看到没有什么问题。
centos1重新开启nginx后：
[root@centos1 ~]# /usr/local/nginx/sbin/nginx[root@centos1 ~]#[root@centos1 ~]# systemctl start keepalived[root@centos1 ~]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability MonitorLoaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)Active: active (running) since 四 2017-10-19 23:59:58 CST; 15s agoProcess: 16786 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)Main PID: 16787 (keepalived)CGroup: /system.slice/keepalived.service├─16787 /usr/sbin/keepalived -D├─16788 /usr/sbin/keepalived -D└─16789 /usr/sbin/keepalived -D10月 20 00:00:00 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:00 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:00 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:00 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.10010月 20 00:00:05 centos1 Keepalived_vrrp[16789]: Sending gratuitous ARP on ens33 for 192.168.40.100
[root@centos1 ~]# ip addr sh ens332: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000link/ether 00:0c:29:83:05:b0 brd ff:ff:ff:ff:ff:ffinet 192.168.40.145/24 brd 192.168.40.255 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.100/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::8783:64ef:f718:b05f/64 scope linkvalid_lft forever preferred_lft forever
可以看到重新抢占回原来的vip了。
再看看centos2：
[root@centos2 ~]# ip addr sh ens332: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000link/ether 00:0c:29:18:67:af brd ff:ff:ff:ff:ff:ffinet 192.168.40.146/24 brd 192.168.40.255 scope global ens33valid_lft forever preferred_lft foreverinet 192.168.40.200/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe18:67af/64 scope linkvalid_lft forever preferred_lft forever
其实检测脚本写得有点累赘和low，但效果还是可以实现的。也可以稍微修改一下，只是为了测试没有让脚本开启nginx。
[root@centos2 ~]# cat /tmp/nginx_check.sh#!/bin/bashNGINX_PID=/usr/local/nginx/logs/nginx.pid/usr/local/nginx/sbin/nginxsleep 5if [ -f $NGINX_PID ]; thennetstat -ntlp | grep `cat $NGINX_PID`if [ $? -eq 0 ]; thenecho "your nginx is running"elsesystemctl stop keepalivedfielsesystemctl stop keepalivedecho "your nginx is no running"fi
完。
本文出自 “运维小记” 博客，请务必保留此出处http://lsfandlinux.blog.51cto.com/13405754/1974737