nginx负载均衡

1. 基础负载均衡配置

在nginx.conf的http块中添加以下配置：

http {
    upstream backend {
        # 默认轮询策略
        server 192.168.1.101:8080;
        server 192.168.1.102:8080;
        server 192.168.1.103:8080;
    }

    server {
        listen 80;
        location / {
            proxy_pass http://backend;
            proxy_set_header Host $host;
        }
    }
}

---

2. 负载均衡策略详解

2.1 加权轮询（Weighted Round Robin）

upstream backend {
    server 192.168.1.101:8080 weight=5;  # 50%流量
    server 192.168.1.102:8080 weight=3;  # 30%流量
    server 192.168.1.103:8080 weight=2;  # 20%流量
}

2.2 最少连接（Least Connections）

upstream backend {
    least_conn;
    server 192.168.1.101:8080;
    server 192.168.1.102:8080;
}

2.3 IP哈希（Session Persistence）

upstream backend {
    ip_hash;
    server 192.168.1.101:8080;
    server 192.168.1.102:8080;
}

2.4 响应时间动态分配（商业版功能）

upstream backend {
    fair;
    server 192.168.1.101:8080;
    server 192.168.1.102:8080;
}

---

3. 高级配置参数

3.1 健康检查机制

upstream backend {
    server 192.168.1.101:8080 max_fails=3 fail_timeout=30s;
    server 192.168.1.102:8080 max_fails=3 fail_timeout=30s;
}

• max_fails：允许的最大失败次数
• fail_timeout：服务器被标记为不可用的时间

3.2 备份服务器配置

upstream backend {
    server 192.168.1.101:8080;
    server 192.168.1.102:8080 backup;  # 备用服务器
}

3.3 慢启动机制

upstream backend {
    server 192.168.1.101:8080 slow_start=30s;
}

---

4. 完整配置示例

http {
    # 定义上游服务器组
    upstream myapp {
        least_conn;
        server app1.example.com:8080 weight=3;
        server app2.example.com:8080 max_fails=2;
        server backup.example.com:8080 backup;
    }

    # 负载均衡服务器配置
    server {
        listen 80;
        server_name loadbalancer.example.com;

        # 静态文件缓存
        location /static/ {
            root /var/www/html;
            expires 30d;
        }

        # 动态请求转发
        location / {
            proxy_pass http://myapp;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
            proxy_connect_timeout 5s;  # 连接超时时间
        }

        # 健康检查端点
        location /nginx_status {
            stub_status on;
            access_log off;
            allow 192.168.1.0/24;
            deny all;
        }
    }
}

---

5. 监控与调试

5.1 查看实时状态

curl http://localhost/nginx_status

Active connections: 3 
server accepts handled requests
 12 12 24 
Reading: 0 Writing: 1 Waiting: 2

5.2 日志分析配置

log_format upstream_log '$remote_addr - $remote_user [$time_local] '
                       '"$request" $status $body_bytes_sent '
                       '"$http_referer" "$http_user_agent" '
                       'upstream: $upstream_addr response_time: $upstream_response_time';

access_log /var/log/nginx/access.log upstream_log;

---

6. 性能优化建议

1.连接复用配置：

proxy_http_version 1.1;
proxy_set_header Connection "";
keepalive 32;  # 每个worker保持的连接数

2.缓冲区优化：

proxy_buffers 16 32k;
proxy_buffer_size 64k;

3.超时控制：

proxy_connect_timeout 5s;
proxy_send_timeout 10s;
proxy_read_timeout 15s;

---

7. 常见问题排查

7.1 502 Bad Gateway

检查项：

ss -tnlp | grep 8080           # 确认后端服务运行
tail -f /var/log/nginx/error.log  # 查看详细错误

7.2 流量分配不均

• 确认是否启用ip_hash导致固定分配
• 检查后端服务器的响应时间差异

---

8. TLS终止配置

server {
    listen 443 ssl;
    ssl_certificate /etc/nginx/ssl/server.crt;
    ssl_certificate_key /etc/nginx/ssl/server.key;
    
    location / {
        proxy_pass http://backend;
        proxy_set_header X-Forwarded-Proto https;
    }
}

配置完成后执行：

sudo nginx -t && sudo systemctl reload nginx

根据实际业务需求选择合适的策略组合，建议先进行压力测试（可使用ab或wrk工具）验证配置效果。