Nginx负载均衡配置实例分析

基本负载均衡配置

以下是一个基本的Nginx负载均衡配置示例：

http {
    upstream backend {
        server backend1.example.com;
        server backend2.example.com;
        server backend3.example.com;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://backend;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
        }
    }
}

负载均衡算法

Nginx支持多种负载均衡算法：

1. 轮询(默认)：请求按顺序分配到后端服务器

   upstream backend {
      server backend1.example.com;
      server backend2.example.com;
   }
   

2. 加权轮询：根据服务器权重分配请求

   upstream backend {
      server backend1.example.com weight=3;
      server backend2.example.com weight=2;
   }
   

3. 最少连接：将请求发送到当前连接数最少的服务器

   upstream backend {
      least_conn;
      server backend1.example.com;
      server backend2.example.com;
   }
   

4. IP哈希：基于客户端IP地址分配请求(保持会话)

   upstream backend {
      ip_hash;
      server backend1.example.com;
      server backend2.example.com;
   }
   

高级配置选项

1. 健康检查：

   upstream backend {
      server backend1.example.com max_fails=3 fail_timeout=30s;
      server backend2.example.com max_fails=3 fail_timeout=30s;
   }
   

2. 备份服务器：

   upstream backend {
      server backend1.example.com;
      server backend2.example.com backup;
   }
   

3. 长连接配置：

   upstream backend {
      server backend1.example.com;
      keepalive 32;
   }
   

完整示例

http {
    upstream backend {
        least_conn;
        server 192.168.1.101:8080 weight=3 max_fails=2 fail_timeout=15s;
        server 192.168.1.102:8080 weight=2;
        server 192.168.1.103:8080 backup;

        keepalive 64;
    }

    server {
        listen 80;
        server_name example.com;

        location / {
            proxy_pass http://backend;
            proxy_http_version 1.1;
            proxy_set_header Connection "";
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

            # 超时设置
            proxy_connect_timeout 5s;
            proxy_send_timeout 10s;
            proxy_read_timeout 30s;
        }
    }
}

常见问题解决方案

1. 会话保持问题：

   • 使用ip_hash或sticky模块
   • 或者将session存储在共享存储(如Redis)

2. 服务器宕机检测：

   server backend1.example.com max_fails=3 fail_timeout=30s;
   

3. 性能优化：

   • 启用keepalive连接
   • 调整缓冲区大小
   • 启用gzip压缩

4. 日志记录：

   log_format upstream_log '$remote_addr - $remote_user [$time_local] '
                         '"$request" $status $body_bytes_sent '
                         '"$http_referer" "$http_user_agent" '
                         'rt=$request_time uct="$upstream_connect_time" '
                         'uht="$upstream_header_time" urt="$upstream_response_time"';
   
   access_log /var/log/nginx/access.log upstream_log;
   

通过以上配置示例，您可以根据实际业务需求调整Nginx的负载均衡策略，实现高性能、高可用的服务架构。