nginx+keepalived 高可用负载均衡

php中文网

发布时间：2016-08-08 09:27:52

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来源于php中文网

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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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系统版本：CentOS release 5.9 (Final) x86 32位
nginx版本： 1.2.8
keepalived版本： 1.2.4
主keepalived:192.168.207.130
从keepalived:192.168.207.131
VIP：192.168.207.140
WEB_1:192.168.207.129 80端口
WEB_2:192.168.207.130 8080端口
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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useradd nginx
vi /usr/local/nginx/conf/nginx.conf

内容如下：

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#运行用户
user nginx nginx;
#启动进程
worker_processes 2;
#全局错误日志及PID文件
error_log logs/error.log notice;
pid logs/nginx.pid;
#工作模式及每个进程连接数上限
events {
use epoll;
worker_connections 1024; #所以nginx支持的总连接数就等于worker_processes * worker_connections
}
#设定http服务器,利用它的反向代理功能提供负载均衡支持
http {
#设定mime类型
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
default_type application/octet-stream; #默认的数据类型
#设定日志格式
log_format main '$remote_addr - $remote_user [$time_local] '
'"$request" $status $bytes_sent '
'"$http_referer" "$http_user_agent" '
'"$gzip_ratio"';
log_format download '$remote_addr - $remote_user [$time_local] '
'"$request" $status $bytes_sent '
'"$http_referer" "$http_user_agent" '
'"$http_range" "$sent_http_content_range"';
#设定请求缓冲
client_header_buffer_size 1k;
large_client_header_buffers 4 4k;
#开启gzip模块
#gzip on;
#gzip_min_length 1100;
#gzip_buffers 4 8k;
#gzip_types text/plain;
#output_buffers 1 32k;
#postpone_output 1460;
#设定access log
access_log logs/access.log main;
client_header_timeout 3m;
client_body_timeout 3m;
send_timeout 3m;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
#设定负载均衡的服务器列表
upstream mysvr {
#weigth参数表示权值,权值越高被分配到的几率越大
server 192.168.207.129:80 weight=5;
server 192.168.207.130:8080 weight=5;
server 192.168.207.131:8080 weight=5;
}
server { #这个是设置web服务的，监听8080端口
listen 8080;
server_name 192.168.207.131; #这个根据系统ip变化
index index.html index.htm;
root /var/www/html;
#error_page 500 502 503 504 /50x.html;
#location = /50x.html {
# root html;
#}
}
#设定虚拟主机
server {
listen 80;
server_name 192.168.207.140; #这里是VIP
#charset gb2312;
#设定本虚拟主机的访问日志
access_log logs/three.web.access.log main;
#如果访问 /img/*, /js/*, /css/* 资源,则直接取本地文件,不通过squid
#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
#location ~ ^/(img|js|css)/{
# root /data3/Html;
# expires 24h;
#}
#对 "/" 启用负载均衡
location / {
proxy_pass http://mysvr; #以这种格式来使用后端的web服务器
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
client_max_body_size 10m;
client_body_buffer_size 128k;
proxy_connect_timeout 90;
proxy_send_timeout 90;
proxy_read_timeout 90;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
}
#设定查看Nginx状态的地址，在安装时要加上--with-http_stub_status_module参数
location /NginxStatus {
stub_status on;
access_log on;
auth_basic "NginxStatus";
auth_basic_user_file conf/htpasswd; #设置访问密码，htpasswd -bc filename username password
}
}
}

3.自定义keepalived配置文件

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vi /etc/keepalived/keepalived.conf

内容如下：

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global_defs {
notification_email {
root@localhost.localdomain
}
notification_email_from notify@keepalived.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/etc/keepalived/check_nginx.sh" ###监控脚本
interval 2 ###监控时间
weight 2 ###目前搞不清楚
}
vrrp_instance VI_1 {
state MASTER ### 设置为主
interface eth0 ### 监控网卡
virtual_router_id 51 ### 这个两台服务器必须一样
priority 101 ### 权重值 MASTRE 一定要高于 BAUCKUP
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_http_port ### 执行监控的服务
}
virtual_ipaddress {
192.168.207.140 ### VIP 地址
}
}

4.写自定义脚本

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下载

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vi /etc/keepalived/check_nginx.sh

内容如下：

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!/bin/bash
A=`ps -C nginx --no-header |wc -l` ## 查看是否有 nginx进程把值赋给变量A
if [ $A -eq 0 ];then ## 如果没有进程值得为零
/usr/local/nginx/sbin/nginx
sleep 3
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
/etc/init.d/keepalived stop ## 则结束 keepalived 进程
fi
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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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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Apr 19 17:42:44 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Apr 19 17:42:45 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.207.140
Apr 19 17:42:45 localhost Keepalived_vrrp: Netlink reflector reports IP 192.168.207.140 added
Apr 19 17:42:45 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.207.140 added
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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Apr 19 17:42:50 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.207.140
Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Apr 19 17:44:06 localhost Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Apr 19 17:44:06 localhost Keepalived_vrrp: Netlink reflector reports IP 192.168.207.140 removed
Apr 19 17:44:06 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.207.140 removed
Apr 19 17:44:06 localhost avahi-daemon[4204]: Withdrawing address record for 192.168.207.140 on eth0.