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：
ng1.laoguang.me 192.168.1.22 ng1

ng2.laoguang.me 192.168.1.23 ng2

lamp1.laoguang.me 192.168.1.24 lamp1

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
tar xvf keepalived-1.2.7.tar.gz

cd keepalived-1.2.7

./configure --prefix=/usr/local/keepalived

##可能会提示安装popt-devel包，yum即可

make && make install

2.2 整理配置文件与脚本
mkdir /etc/keepalived

##keepalived默认配置文件从/etc/keepalived下读取

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

##就一个二进制文件，直接拷贝过去即可，多的话就更改PATH吧

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

##脚本的额外配置文件读取位置

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

##启动脚本你懂得

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

##我们关键的keepalived配置文件

2.3 修改ng1的/etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {

notification_email {

ibuler@qq.com ##出故障发送邮件给谁

}

notification_email_from keepalived@localhost ##故障用哪个邮箱发送邮件

smtp_server 127.0.0.1 ##SMTP_Server IP

smtp_connect_timeout 30 ##超时时间

router_id LVS_DEVEL ##服务器标识

}

vrrp_instance VI_1 {

state BACKUP

##状态，都为BACKUP，它们会推选Master，如果你写MASTER，它就会是Master，

##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

interface eth0 ##发送VRRP的接口，仔细看你的是不是eth0

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

priority 100 ##重要的优先级哦

nopreempt ##不抢占，一个故障时，重启后恢复后不抢占意资源

advert_int 1 ##同步间隔时长

authentication { ##认证

auth_type PASS ##认证方式

auth_pass www.laoguang.me ##密钥

}

virtual_ipaddress {

192.168.1.18/24 dev eth0 ##VIP

}

}

##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
scp /etc/keepalived/keepalived.conf 192.168.1.23:/etc/keepalived/

##Ng2上

vi /etc/keepalived/keepalived.conf priority 90 ##其它一致

2.4 ng1,ng2上启动keepalived
service keepalived start

查看日志
tail /var/log/messages

Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Entering BACKUP STATE

Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP sockpool: [ifindex(2), proto(112), fd(11,12)]

Nov 27 08:07:54 localhost Keepalived_healthcheckers[41870]: Using LinkWatch kernel netlink reflector...

Nov 27 08:07:54 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) forcing a new MASTER election

Nov 27 08:07:55 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Transition to MASTER STATE

Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Entering MASTER STATE

Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) setting protocol VIPs.

Nov 27 08:07:56 localhost Keepalived_healthcheckers[41870]: Netlink reflector reports IP 192.168.1.18 added

Nov 27 08:07:56 localhost Keepalived_vrrp[41871]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.1.18

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
ip addr ##ng1上

....省略

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:e8:90:0b brd ff:ff:ff:ff:ff:ff

inet 192.168.1.22/24 brd 192.168.1.255 scope global eth0

inet 192.168.1.18/32 scope global eth0

inet6 fe80::20c:29ff:fee8:900b/64 scope link

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
service keepalived stop

ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:e8:90:0b brd ff:ff:ff:ff:ff:ff

inet 192.168.1.22/24 brd 192.168.1.255 scope global eth0

inet6 fe80::20c:29ff:fee8:900b/64 scope link

valid_lft forever preferred_lft forever

3.2 查看ng2上是否绑定了vip
ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 00:0c:29:dd:00:77 brd ff:ff:ff:ff:ff:ff

inet 192.168.1.23/24 brd 192.168.1.255 scope global eth0

inet 192.168.1.18/32 scope global eth0

inet6 fe80::20c:29ff:fedd:77/64 scope link

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
vi /etc/nginx/nginx.conf

user nginx nginx; ##运行nginx的用户和组

worker_processes 2; ##启动进程数

error_log /var/log/nginx/error.log notice; ##错误日志记录

pid /tmp/nginx.pid; ##pid存放位置

worker_rlimit_nofile 65535; ##线程最大打开文件数，须配合ulimit -SHn使用

events {

use epoll; ##工作模型

worker_connections 65536; ##单进程最大连接数

}

http { ##http模块

include mime.types; ##包含进来

default_type application/octet-stream; ##默认类型

log_format main '$remote_addr - $remote_user [$time_local] "$request" '

'$status $body_bytes_sent "$http_referer" '

'"$http_user_agent" "$http_x_forwarded_for"';

##日志格式

access_log /var/logs/nginx/http.access.log main; ##访问日志

client_max_body_size 20m; ##最大请求文件大小

client_header_buffer_size 16k; ##来自客户端请求header_buffer大小

large_client_header_buffers 4 16k; ##较大请求缓冲个数与大小

sendfile on; ##内核空间直接发送到tcp队列

tcp_nopush on;

tcp_nodelay on;

keepalive_timeout 65; ##长连接时长

gzip on; ##启用压缩

gzip_min_length 1k; ##最小压缩大小

gzip_buffers 4 16k; ##压缩缓冲

gzip_http_version 1.1; ##支持协议

gzip_comp_level 2; ##压缩等级

gzip_types text/plain application/x-javascript text/css application/xml; ##压缩类型

gzip_vary on; ##前端缓存服务器可以缓存压缩过的页面

upstream laoguang.me { ##用upstream模块定义集群与RS

server 192.168.1.24:80 max_fails=3fail_timeout=10s; ##RS的地址，最大错误数与超时时间，超过了自动剔除

server 192.168.1.25:80 max_fails=3fail_timeout=10s;

}

server {

listen 80; ##监听端口

server_name 192.168.1.18; ##servername

root html; ##根目录

index index.html index.htm; ##你懂得

#charset koi8-r;

access_log logs/192.168.1.18.access.log main;

##这个server的访问日志

location / {

proxy_pass http://laoguang.me; ##反向代理

proxy_redirect off;

proxy_set_header X-Real-IP $remote_addr;

##真实客户ip告诉后端

proxy_set_header X-Forwarded-For Proxy_add_x_forwarded_for;

}

location /nginx {

access_log off;

stub_status on; ##状态页面

}

error_page 500 502 503 504 /50x.html;

location = /50x.html {

root html;

}

}

}

4.2 拷贝到ng2上一份
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
service httpd start

ng1重启nginx
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。