Nginx+Keepalived简单构建高可用集群

转自:http://laoguang.blog.51cto.com/6013350/1099103

以前一直用heartbeat或corosync+pacemaker构建高可用集群,现在发现keepalived实现起来更简单。
keepalived的master向backup发送广播,当backup一段时间收不到对方传来的VRRP广播时,backup会通过竞选一个master,master就会重新持有资源。具体的理论知识参见
http://bbs.ywlm.net/thread-790-1-1.html

实验目标:2台Nginx+Keepalived 2台Lamp构建高可用Web集群

规划:

   
   
   
   
  1. ng1.laoguang.me 192.168.1.22 ng1
  2. ng2.laoguang.me 192.168.1.23 ng2
  3. lamp1.laoguang.me 192.168.1.24 lamp1
  4. lamp2.laoguang.me 192.168.1.25 lamp2

拓扑:

一.基本环境准备
ng1,ng2上安装nginx
lamp1,lamp2上构建LAMP或只安装httpd,我只安装了Httpd,这里不给大家演示了,有需要请看我的其它博文,更改lamp1,lamp2的index.html的内容分别为lamp1和lamp2,以容易区分,实际集群中内容应该是一致的,由共享存储提供。

二.ng1,ng2上安装配置keepalived
下载地址:http://www.keepalived.org/download.html
2.1 安装keepalived

   
   
   
   
  1. tar xvf keepalived-1.2.7.tar.gz
  2. cd keepalived-1.2.7
  3. ./configure --prefix=/usr/local/keepalived
  4. ##可能会提示安装popt-devel包,yum即可
  5. make && make install

2.2 整理配置文件与脚本

   
   
   
   
  1. mkdir /etc/keepalived
  2. ##keepalived默认配置文件从/etc/keepalived下读取
  3. cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
  4. ##就一个二进制文件,直接拷贝过去即可,多的话就更改PATH吧
  5. cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
  6. ##脚本的额外配置文件读取位置
  7. cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
  8. ##启动脚本你懂得
  9. cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
  10. ##我们关键的keepalived配置文件

2.3 修改ng1的/etc/keepalived/keepalived.conf

   
   
   
   
  1. ! Configuration File for keepalived
  2. global_defs {
  3. notification_email {
  4. [email protected] ##出故障发送邮件给谁
  5. }
  6. notification_email_from keepalived@localhost ##故障用哪个邮箱发送邮件
  7. smtp_server 127.0.0.1 ##SMTP_Server IP
  8. smtp_connect_timeout 30 ##超时时间
  9. router_id LVS_DEVEL ##服务器标识
  10. }
  11. vrrp_instance VI_1 {
  12. state BACKUP
  13. ##状态,都为BACKUP,它们会推选Master,如果你写MASTER,它就会是Master,
  14. ##当Master故障时Backup会成为Master,当原来的Master恢复后,原来的Master会成为Master
  15. interface eth0 ##发送VRRP的接口,仔细看你的是不是eth0
  16. virtual_router_id 51 ##虚拟路由标识,同一个组应该用一个,即Master与Backup同一个
  17. priority 100 ##重要的优先级哦
  18. nopreempt ##不抢占,一个故障时,重启后恢复后不抢占意资源
  19. advert_int 1 ##同步间隔时长
  20. authentication { ##认证
  21. auth_type PASS ##认证方式
  22. auth_pass www.laoguang.me ##密钥
  23. }
  24. virtual_ipaddress {
  25. 192.168.1.18 ##VIP
  26. }
  27. }
  28. ##后面的删除吧,LVS上才有用

拷贝到ng2上一份,只修改priority 90 即可

   
   
   
   
  1. scp /etc/keepalived/keepalived.conf 192.168.1.23:/etc/keepalived/
  2. ##Ng2上
  3. vi /etc/keepalived/keepalived.conf priority 90 ##其它一致

2.4 ng1,ng2上启动keepalived

   
   
   
   
  1. service keepalived start

查看日志

   
   
   
   
  1. tail /var/log/messages
  2. Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Entering BACKUP STATE
  3. Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP sockpool: [ifindex(2), proto(112), fd(11,12)]
  4. Nov 27 08:07:54 localhost Keepalived_healthcheckers[41870]: Using LinkWatch kernel netlink reflector...
  5. Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) forcing a new MASTER election
  6. Nov 27 08:07:55 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Transition to MASTER STATE
  7. Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Entering MASTER STATE
  8. Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) setting protocol VIPs.
  9. Nov 27 08:07:56 localhost Keepalived_healthcheckers[41870]: Netlink reflector reports IP 192.168.1.18 added
  10. Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.18
  11. Nov 27 08:08:01 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.18

查看vip绑定到哪台机器上了

   
   
   
   
  1. ip addr ##ng1上
  2. ....省略
  3. 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
  4. link/ether 00:0c:29:e8:90:0b brd ff:ff:ff:ff:ff:ff
  5. inet 192.168.1.22/24 brd 192.168.1.255 scope global eth0
  6. inet 192.168.1.18/32 scope global eth0
  7. inet6 fe80::20c:29ff:fee8:900b/64 scope link
  8. valid_lft forever preferred_lft forever

由此可知vip绑定到ng1上了
三,Keepalived测试

3.1 关闭ng1上的keepalived或者直接关闭ng1 查看vip转移情况

   
   
   
   
  1. service keepalived stop
  2. ip addr
  3. 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
  4. link/ether 00:0c:29:e8:90:0b brd ff:ff:ff:ff:ff:ff
  5. inet 192.168.1.22/24 brd 192.168.1.255 scope global eth0
  6. inet6 fe80::20c:29ff:fee8:900b/64 scope link
  7. valid_lft forever preferred_lft forever

3.2 查看ng2上是否绑定了vip

   
   
   
   
  1. ip addr
  2. 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
  3. link/ether 00:0c:29:dd:00:77 brd ff:ff:ff:ff:ff:ff
  4. inet 192.168.1.23/24 brd 192.168.1.255 scope global eth0
  5. inet 192.168.1.18/32 scope global eth0
  6. inet6 fe80::20c:29ff:fedd:77/64 scope link
  7. valid_lft forever preferred_lft forever

由此可知ip转移正常,keepalived设置成功

四.配置Nginx做反向代理

4.1 修改nginx配置文件

   
   
   
   
  1. vi /etc/nginx/nginx.conf
  2. user nginx nginx; ##运行nginx的用户和组
  3. worker_processes 2; ##启动进程数
  4. error_log /var/log/nginx/error.log notice; ##错误日志记录
  5. pid /tmp/nginx.pid; ##pid存放位置
  6. worker_rlimit_nofile 65535; ##线程最大打开文件数,须配合ulimit -SHn使用
  7. events {
  8. use epoll; ##工作模型
  9. worker_connections 65536; ##单进程最大连接数
  10. }
  11. http { ##http模块
  12. include mime.types; ##包含进来
  13. default_type application/octet-stream; ##默认类型
  14. log_format main '$remote_addr - $remote_user [$time_local] "$request" '
  15. '$status $body_bytes_sent "$http_referer" '
  16. '"$http_user_agent" "$http_x_forwarded_for"';
  17. ##日志格式
  18. access_log /var/logs/nginx/http.access.log main; ##访问日志
  19. client_max_body_size 20m; ##最大请求文件大小
  20. client_header_buffer_size 16k; ##来自客户端请求header_buffer大小
  21. large_client_header_buffers 4 16k; ##较大请求缓冲个数与大小
  22. sendfile on; ##内核空间直接发送到tcp队列
  23. tcp_nopush on;
  24. tcp_nodelay on;
  25. keepalive_timeout 65; ##长连接时长
  26. gzip on; ##启用压缩
  27. gzip_min_length 1k; ##最小压缩大小
  28. gzip_buffers 4 16k; ##压缩缓冲
  29. gzip_http_version 1.1; ##支持协议
  30. gzip_comp_level 2; ##压缩等级
  31. gzip_types text/plain application/x-javascript text/css application/xml; ##压缩类型
  32. gzip_vary on; ##前端缓存服务器可以缓存压缩过的页面
  33. upstream laoguang.me { ##用upstream模块定义集群与RS
  34. server 192.168.1.24:80 max_fails=3 fail_timeout=10s; ##RS的地址,最大错误数与超时时间,超过了自动剔除
  35. server 192.168.1.25:80 max_fails=3 fail_timeout=10s;
  36. }
  37. server {
  38. listen 80; ##监听端口
  39. server_name 192.168.1.18; ##servername
  40. root html; ##根目录
  41. index index.html index.htm; ##你懂得
  42. #charset koi8-r;
  43. access_log logs/192.168.1.18.access.log main;
  44. ##这个server的访问日志
  45. location / {
  46. proxy_pass http://laoguang.me; ##反向代理
  47. proxy_redirect off;
  48. proxy_set_header X-Real-IP $remote_addr;
  49. ##真实客户ip告诉后端
  50. proxy_set_header X-Forwarded-For Proxy_add_x_forwarded_for;
  51. }
  52. location /nginx {
  53. access_log off;
  54. stub_status on; ##状态页面
  55. }
  56. error_page 500 502 503 504 /50x.html;
  57. location = /50x.html {
  58. root html;
  59. }
  60. }
  61. }

4.2 拷贝到ng2上一份

   
   
   
   
  1. scp /etc/nginx/nginx.conf 192.168.1.23:/etc/nginx/

4.3 测试反向代理能否负载均衡

lamp1,lamp2启动httpd

   
   
   
   
  1. service httpd start

ng1重启nginx

   
   
   
   
  1. service nginx restart

用RealIp访问测试能否轮询
http://192.168.1.22

同样测试ng2,如果都能实现负载均衡,那么继续

五.测试keepalived与nginx配合运行

现在192.168.1.18在 ng2上, 访问 http://192.168.1.18 测试能否轮询
ng2上 service keepalived stop 访问测试 http://192.168.1.18 能否轮询
关闭lamp1上的service httpd stop 访问测试http://192.168.1.18 是否会报错

到此高可用webserver构建完毕,没有单点故障,任何一点故障不影响业务。

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