nginx+keepalived 高可用负载均衡

话就不多说了，nginx安装与配置，还有负载均衡呢，可以看我写的另一篇文章《nginx负载均衡实战》，还有关于负载均衡呢，大家可以看一下我写的另外两篇文章，一个是《lvs+keepalived负载均衡》，另一个是《haproxy+keepalived负载均衡》,三种负载均衡的区别呢，可以看一下我转载的一篇文章《软件级负载均衡器(LVS/HAProxy/Nginx)的特点简介和对比》，下面直接进入配置步骤：

1.系统环境

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1. 系统版本：CentOS release 5.9 (Final) x86 32位
2. nginx版本： 1.2.8
3. keepalived版本： 1.2.4
5. 主keepalived:192.168.207.130
7. 从keepalived:192.168.207.131
10. VIP：192.168.207.140
11. WEB_1:192.168.207.129 80端口
12. WEB_2:192.168.207.130 8080端口
13. WEB_3:192.168.207.131 8080端口

2.自定义nginx配置文件

在192.168.207.130和192.168.207.131上操作

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1. useradd nginx
2. vi /usr/local/nginx/conf/nginx.conf

内容如下：

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1. #运行用户
2. user nginx nginx;
3. #启动进程
4. worker_processes 2;
5. #全局错误日志及PID文件
6. error_log logs/error.log notice;
7. pid logs/nginx.pid;
8. #工作模式及每个进程连接数上限
9. events {
10. use epoll;
11. worker_connections 1024; #所以nginx支持的总连接数就等于worker_processes * worker_connections
12. }
13. #设定http服务器,利用它的反向代理功能提供负载均衡支持
14. http {
15. #设定mime类型
16. include mime.types; #这个是说nginx支持哪些多媒体类型，可以到conf/mime.types查看支持哪些多媒体
17. default_type application/octet-stream; #默认的数据类型
18. #设定日志格式
20. log_format main '$remote_addr - $remote_user [$time_local] '
21. '"$request" $status $bytes_sent '
22. '"$http_referer" "$http_user_agent" '
23. '"$gzip_ratio"';
25. log_format download '$remote_addr - $remote_user [$time_local] '
26. '"$request" $status $bytes_sent '
27. '"$http_referer" "$http_user_agent" '
28. '"$http_range" "$sent_http_content_range"';
29. #设定请求缓冲
30. client_header_buffer_size 1k;
31. large_client_header_buffers 4 4k;
32. #开启gzip模块
33. #gzip on;
34. #gzip_min_length 1100;
35. #gzip_buffers 4 8k;
36. #gzip_types text/plain;
37. #output_buffers 1 32k;
38. #postpone_output 1460;
39. #设定access log
40. access_log logs/access.log main;
41. client_header_timeout 3m;
42. client_body_timeout 3m;
43. send_timeout 3m;
44. sendfile on;
45. tcp_nopush on;
46. tcp_nodelay on;
47. keepalive_timeout 65;
48. #设定负载均衡的服务器列表
50. upstream mysvr {
51. #weigth参数表示权值,权值越高被分配到的几率越大
52. server 192.168.207.129:80 weight=5;
53. server 192.168.207.130:8080 weight=5;
54. server 192.168.207.131:8080 weight=5;
55. }
56. server { #这个是设置web服务的，监听8080端口
57. listen 8080;
58. server_name 192.168.207.131; #这个根据系统ip变化
59. index index.html index.htm;
60. root /var/www/html;
61. #error_page 500 502 503 504 /50x.html;
62. #location = /50x.html {
63. # root html;
64. #}
65. }
66. #设定虚拟主机
67. server {
68. listen 80;
69. server_name 192.168.207.140; #这里是VIP
70. #charset gb2312;
71. #设定本虚拟主机的访问日志
72. access_log logs/three.web.access.log main;
73. #如果访问 /img/*, /js/*, /css/* 资源,则直接取本地文件,不通过squid
74. #如果这些文件较多,不推荐这种方式,因为通过squid的缓存效果更好
75. #location ~ ^/(img|js|css)/{
76. # root /data3/Html;
77. # expires 24h;
78. #}
79. #对 "/" 启用负载均衡
80. location / {
81. proxy_pass http://mysvr; #以这种格式来使用后端的web服务器
82. proxy_redirect off;
83. proxy_set_header Host $host;
84. proxy_set_header X-Real-IP $remote_addr;
85. proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
86. client_max_body_size 10m;
87. client_body_buffer_size 128k;
88. proxy_connect_timeout 90;
89. proxy_send_timeout 90;
90. proxy_read_timeout 90;
91. proxy_buffer_size 4k;
92. proxy_buffers 4 32k;
93. proxy_busy_buffers_size 64k;
94. proxy_temp_file_write_size 64k;
95. }
96. #设定查看Nginx状态的地址 ，在安装时要加上--with-http_stub_status_module参数
97. location /NginxStatus {
98. stub_status on;
99. access_log on;
100. auth_basic "NginxStatus";
101. auth_basic_user_file conf/htpasswd; #设置访问密码，htpasswd -bc filename username password
102. }
103. }
104. }

3.自定义keepalived配置文件

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1. vi /etc/keepalived/keepalived.conf

内容如下：

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1. global_defs {
2. notification_email {
3. [e-mail]
4. }
5. notification_email_from [e-mail]
6. smtp_server 127.0.0.1
7. smtp_connect_timeout 30
8. router_id LVS_DEVEL
9. }
11. vrrp_script chk_http_port {
12. script "/etc/keepalived/check_nginx.sh" ###监控脚本
13. interval 2 ###监控时间
14. weight 2 ###目前搞不清楚
15. }
16. vrrp_instance VI_1 {
17. state MASTER ### 设置为 主
18. interface eth0 ### 监控网卡
19. virtual_router_id 51 ### 这个两台服务器必须一样
20. priority 101 ### 权重值 MASTRE 一定要高于 BAUCKUP
21. authentication {
22. auth_type PASS
23. auth_pass 1111
24. }
25. track_script {
26. chk_http_port ### 执行监控的服务
27. }
28. virtual_ipaddress {
29. 192.168.207.140 ### VIP 地址
30. }
31. }

4.写自定义脚本

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1. vi /etc/keepalived/check_nginx.sh

内容如下：

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1. !/bin/bash
2. A=`ps -C nginx --no-header |wc -l` ## 查看是否有 nginx进程 把值赋给变量A
3. if [ $A -eq 0 ];then ## 如果没有进程值得为 零
4. /usr/local/nginx/sbin/nginx
5. sleep 3
6. if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
7. /etc/init.d/keepalived stop ## 则结束 keepalived 进程
8. fi
9. fi

这里是检查nginx是否启动好，如果没有启动，先启动 nginx，隔了3秒后还没有启动好，则将keepalived进程也关闭，这样从keepalived就能接手过去了，提供高可用性，在这里呢，keepalived服务是提供高可用性，而nginx是提供后端web服务器的负载均衡。
这里还要给脚本加上执行权限，如下

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1. chmod +x /etc/keepalived/check_nginx.sh

5.启动服务，并测试

在这里先说一下啊，在WEB_1上，我是使用系统自带的apache昨晚web服务器的，比较省事，这样呢，我只要启动好主从keepalived就ok了，因为它会利用check_nginx.sh脚本来自动启动nginx。
都启动好了。
访问http://192.168.207.140就可以轮训访问后端的三台web服务器内容啦
这里我们把主keepalived服务给关掉，来测试高可用性
然后会在从keepalived服务器上的/var/log/messages看到这样的日志

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1. Apr 19 17:42:44 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
2. Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
3. Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
4. Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.207.140
5. Apr 19 17:42:45 localhost Keepalived_vrrp: Netlink reflector reports IP 192.168.207.140 added
6. Apr 19 17:42:45 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.207.140 added
7. Apr 19 17:42:45 localhost avahi-daemon[4204]: Registering new address record for 192.168.207.140 on eth0.

继续访问http://192.168.207.140，依旧可以访问后端的三台web服务器
然后再把原主keepalived打开，可以观察到原从keepalived服务器的日志显示

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1. Apr 19 17:42:50 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.207.140
2. Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
3. Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
4. Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
5. Apr 19 17:44:06 localhost Keepalived_vrrp: Netlink reflector reports IP 192.168.207.140 removed
6. Apr 19 17:44:06 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.207.140 removed
7. Apr 19 17:44:06 localhost avahi-daemon[4204]: Withdrawing address record for 192.168.207.140 on eth0.

说明有恢复了原来的主从结果。
生产环境中，后端的机器也可能会挂掉，但是呢，这就不用你操心啦，nginx会自动把session分配到好的后端web服务器上的啦

ok，到这里全部结束了，实践亲测，祝君成功

From: http://blog.csdn.net/zmj_88888888/article/details/8825471

以上就介绍了nginx+keepalived 高可用负载均衡，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。