引言

Nginx高可用是保证系统稳定性的关键。本文介绍Nginx高可用架构设计。

一、Keepalived主备切换

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# 安装Keepalived
yum install keepalived

# 主节点配置 /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    
    virtual_ipaddress {
        192.168.1.100
    }
}

# 备节点配置
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 90
    # ... 其他配置相同
}

二、负载均衡配置

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upstream backend {
    # 轮询（默认）
    server 192.168.1.10:8080;
    server 192.168.1.11:8080;
    
    # 加权轮询
    server 192.168.1.10:8080 weight=3;
    server 192.168.1.11:8080 weight=1;
    
    # IP Hash
    ip_hash;
    server 192.168.1.10:8080;
    server 192.168.1.11:8080;
    
    # 最少连接
    least_conn;
    server 192.168.1.10:8080;
    server 192.168.1.11:8080;
}

server {
    listen 80;
    server_name example.com;
    
    location / {
        proxy_pass http://backend;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

三、健康检查

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upstream backend {
    server 192.168.1.10:8080 max_fails=3 fail_timeout=30s;
    server 192.168.1.11:8080 max_fails=3 fail_timeout=30s;
    
    # 备用服务器
    server 192.168.1.12:8080 backup;
}

四、监控脚本

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#!/bin/bash
# check_nginx.sh

counter=0
while [ $counter -lt 3 ]; do
    nginx_status=$(systemctl is-active nginx)
    if [ "$nginx_status" = "active" ]; then
        exit 0
    fi
    let counter++
    sleep 1
done

# Nginx异常，停止Keepalived
systemctl stop keepalived

总结

Nginx高可用核心：

  1. Keepalived：主备切换
  2. 负载均衡：分流请求
  3. 健康检查：自动摘除故障节点
  4. 监控告警：及时发现问题

参考资料