【Nginx】负载均衡配置详解

Nginx作为高性能的HTTP服务器和反向代理服务器，提供了强大的负载均衡功能。本文将详细介绍Nginx负载均衡的配置方法和相关策略。

一、基础负载均衡配置

1.单服务示例配置

配置nginx.conf模块

在Nginx配置文件中定义upstream模块：

powershell 复制代码

worker_processes auto;

events {
    worker_connections 1024;
}

http{
	upstream backend {
	    server 192.168.1.101:8080;
	    server 192.168.1.102:8080;
	    server 192.168.1.103:8080;
	}
	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;
	    }
	}
}

2.多服务配置

powershell 复制代码

worker_processes auto;

events {
    worker_connections 1024;
}

http{
    # 定义一个新的日志格式，包含 upstream_addr
    log_format custom '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for" '
                      'upstream: $upstream_addr';

    upstream server1{
        server 192.168.211.5:9529;
        server 192.168.211.169:9529;
    }

    upstream server2{
        server 192.168.211.5:9528;
        server 192.168.211.169:9528;
    }

    server {
        listen       80;
        server_name  localhost;

        # 使用自定义的日志格式
        access_log /opt/nginx/logs/access.log custom;

        location ~ ^/server1/(.*)$ {
            proxy_pass http://server1/$1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            # proxy_set_header Content-Type application/json;
        }


        location ~ ^/server2/(.*)$ {
            proxy_pass http://server2/$1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }

        location ~* \.(css|js|html)$ {
            root  /opt/nginx/html;    # 在本例中的绝对路径为 /usr/local/nginx/html
        }

        error_page 404 /404.html;
        error_page 500 502 503 504 /50x.html;
    }
}

3.docker启动nginx脚本

该脚本需要根据自己的docker镜像启动nginx的配置去修改

powershell 复制代码

#!/bin/bash

# 定义变量
CONTAINER_NAME="nlb-nginx"
IMAGE_NAME="nginx:1.26"
HOST_PORT="9090"  # 主机端口
CONTAINER_PORT="80"  # 容器端口
PORT_MAPPING="${HOST_PORT}:${CONTAINER_PORT}"
NGINX_CONF_PATH="$(pwd)/nginx_server/nginx.conf"
LOG_DIR="/var/server1/logs/proxy"
TEST_URL="http://localhost:${HOST_PORT}"

# 确保日志目录存在
if [ ! -d "$LOG_DIR" ]; then
    echo "Creating log directory: $LOG_DIR"
    mkdir -p "$LOG_DIR" || {
        echo "Failed to create log directory."
        exit 1
    }
fi

# 停止并删除旧容器（如果存在）
echo "Stopping and removing existing container: $CONTAINER_NAME"
docker stop "$CONTAINER_NAME" > /dev/null 2>&1
docker rm -f "$CONTAINER_NAME" > /dev/null 2>&1

# 启动新的 Nginx 容器
echo "Starting new Nginx container: $CONTAINER_NAME"
docker run -itd \
  --name "$CONTAINER_NAME" \
  -p "$PORT_MAPPING" \
  -v "$NGINX_CONF_PATH:/opt/nginx/etc/nginx.conf" \
  -v "$LOG_DIR:/opt/nginx/logs" \
  "$IMAGE_NAME" \
  /opt/nginx/sbin/nginx -c /opt/nginx/etc/nginx.conf -g "daemon off;" || {
    echo "Failed to start container $CONTAINER_NAME."
    exit 1
}

# 验证容器状态
echo "Verifying container status..."
if docker ps -f name="$CONTAINER_NAME" | grep -q "$CONTAINER_NAME"; then
    echo "Container $CONTAINER_NAME is running successfully."
else
    echo "Container $CONTAINER_NAME failed to start."
    exit 1
fi

# 测试访问
echo "Testing access to $TEST_URL..."
if curl -s -o /dev/null -w "%{http_code}" "$TEST_URL" | grep -q "200"; then
    echo "Nginx is accessible at $TEST_URL"
else
    echo "Failed to access Nginx at $TEST_URL"
    exit 1
fi

echo "Deployment completed successfully!"

4.测试负载均衡-脚本

1.后端服务

示例：使用 Python Flask 实现

在每台后端服务器上运行以下简单的 Flask 应用程序：

后端服务器 1 (192.168.211.5)：

python 复制代码

from flask import Flask

app = Flask(__name__)

@app.route('/nginx_test')
def server_info():
    return "192.168.211.5"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=9529)

后端服务器 2 (192.168.211.75)：

python 复制代码

from flask import Flask

app = Flask(__name__)

@app.route('/nginx_test')
def server_info():
    return "192.168.211.75"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=9529)

2.前端html测试

html 复制代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Test Nginx Smartlabel</title>
</head>
<body>
    <h1>Nginx and Flask Test Page</h1>
    <p>Server Response: <strong id="server-response">Loading...</strong></p>

    <script>
        // JavaScript to send a GET request to the Flask endpoint
        fetch('/server1/nginx_test', {
            method: 'GET'
        })
        .then(response => response.json()) // Parse the JSON response
        .then(data => {
            document.getElementById('server-response').innerText = JSON.stringify(data);
        })
        .catch(error => {
            document.getElementById('server-response').innerText = 'Error fetching data';
        });
    </script>
</body>
</html>

访问测试页面
打开浏览器并访问 http://localhost:9090/test.html。页面会显示类似以下内容：

bash 复制代码

Nginx and Flask Test Page
Server Response: {"ip_info":"192.168.211.236","server":"server1"}

二、负载均衡策略

Nginx支持多种负载均衡算法：

轮询(默认)

powershell 复制代码

upstream backend {
    server 192.168.1.101;
    server 192.168.1.102;
}

加权轮询

powershell 复制代码

upstream backend {
    server 192.168.1.101 weight=3;
    server 192.168.1.102 weight=1;
}

IP哈希(保持会话)

powershell 复制代码

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

最少连接数

powershell 复制代码

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

基于响应时间(商业版)

powershell 复制代码

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

三、高级配置选项

服务器状态参数

powershell 复制代码

upstream backend {
    server 192.168.1.101 max_fails=3 fail_timeout=30s;
    server 192.168.1.102 backup;
    server 192.168.1.103 down;
}

max_fails: 最大失败次数
fail_timeout: 失败超时时间
backup: 备用服务器
down: 标记服务器不可用
健康检查(商业版)

powershell 复制代码

upstream backend {
    zone backend 64k;
    server 192.168.1.101;
    server 192.168.1.102;
    
    health_check interval=5s fails=3 passes=2 uri=/health;
}

四、TCP/UDP负载均衡

Nginx也可以用于TCP/UDP负载均衡：

powershell 复制代码

stream {
    upstream tcp_backend {
        server 192.168.1.101:3306;
        server 192.168.1.102:3306;
    }
    
    server {
        listen 3306;
        proxy_pass tcp_backend;
    }
}

五、最佳实践

会话保持：对于需要会话的应用，使用ip_hash或sticky模块
健康检查：配置合理的健康检查参数
日志记录：记录后端服务器的响应时间和状态
超时设置：适当调整proxy连接超时时间
缓冲区优化：根据应用特点调整缓冲区大小

六、常见问题

502错误：检查后端服务器是否可用
负载不均：调整权重或更换算法
性能问题：优化worker_processes和worker_connections

七、总结

通过合理配置Nginx负载均衡，可以显著提高系统的可用性和性能。根据实际业务需求选择合适的负载均衡策略和参数配置是关键。