Web 服务器负载均衡深度解析：Nginx 配置实践完全指南

文章目录

• • 1. 负载均衡基础理论
  • • 1.1 什么是负载均衡？
    • • 核心价值：
    • 1.2 负载均衡的架构位置
    • 1.3 负载均衡的类型分类
  • 2. Nginx 负载均衡详解
  • • 2.1 Nginx 架构优势
    • 2.2 Nginx 负载均衡核心配置
    • • 基础配置结构：
  • 3. Nginx 负载均衡算法实践
  • • 3.1 轮询算法（Round Robin）
    • • 流量分发示意图：
    • 3.2 加权轮询算法（Weighted Round Robin）
    • 3.3 IP哈希算法（IP Hash）
    • 3.4 最少连接算法（Least Connections）
  • 4. 高级负载均衡配置
  • • 4.1 健康检查配置
    • 4.2 会话保持（Session Persistence）
    • 4.3 TCP/UDP 负载均衡
  • 5. 实战：完整的微服务负载均衡配置
  • • 5.1 多环境配置管理
    • 5.2 上游服务器配置文件
    • 5.3 虚拟主机配置
  • 6. 性能优化与监控
  • • 6.1 Nginx 性能调优
    • 6.2 监控配置
    • 6.3 Prometheus + Grafana 监控仪表板
  • 7. 故障排除与最佳实践
  • • 7.1 常见问题排查
    • 7.2 最佳实践总结
  • 8. 总结

负载均衡是现代分布式系统的核心组件，它能有效提高系统的可用性、扩展性和性能。本文将从基础概念到高级配置，全面讲解负载均衡的原理及 Nginx 的实践应用。

1. 负载均衡基础理论

1.1 什么是负载均衡？

负载均衡（Load Balancing）是一种将网络流量或计算负载分配到多个服务器的技术，目的是优化资源使用、最大化吞吐量、最小化响应时间，并避免单点故障。

核心价值：

• 高可用性：某个服务器故障时，流量自动转移到其他健康服务器
• 可扩展性：通过添加更多服务器轻松扩展系统容量
• 性能优化：减少单个服务器的负载，提高响应速度
• 维护便利：可以在不影响服务的情况下进行服务器维护

1.2 负载均衡的架构位置

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数据层

服务器集群

负载均衡层

客户端层

客户端1

客户端2

…

客户端n

负载均衡器

服务器1

服务器2

服务器3

…

服务器n

数据库主库

数据库从库

缓存集群

1.3 负载均衡的类型分类

2. Nginx 负载均衡详解

2.1 Nginx 架构优势

Nginx 作为反向代理服务器，具有以下负载均衡优势：

2.2 Nginx 负载均衡核心配置

基础配置结构：

# nginx.conf 主配置文件结构
http {
# 上游服务器组定义（负载均衡后端）
upstream backend_servers {
# 负载均衡算法
# 服务器配置
# 健康检查参数
}

server {
listen 80;
server_name example.com;

location / {
# 代理到上游服务器组
proxy_pass http://backend_servers;

# 代理相关配置
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;

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

3. Nginx 负载均衡算法实践

3.1 轮询算法（Round Robin）

http {
upstream backend {
# 默认就是轮询算法
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;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

# 连接超时时间
proxy_connect_timeout 5s;

# 发送请求超时时间
proxy_send_timeout 10s;

# 接收响应超时时间
proxy_read_timeout 30s;

# 启用缓冲
proxy_buffering on;
proxy_buffer_size 4k;
proxy_buffers 8 4k;
proxy_busy_buffers_size 8k;
}
}
}

流量分发示意图：

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客户端请求

Nginx负载均衡器

服务器1192.168.1.101:8080

服务器2192.168.1.102:8080

服务器3192.168.1.103:8080

响应1

响应2

响应3

3.2 加权轮询算法（Weighted Round Robin）

http {
upstream backend {
# 权重配置，数字越大分配的请求越多
server 192.168.1.101:8080 weight=5; # 50%的流量
server 192.168.1.102:8080 weight=3; # 30%的流量
server 192.168.1.103:8080 weight=2; # 20%的流量

# 权重计算公式：单个服务器权重 / 总权重
# 服务器1: 5/(5+3+2) = 50%
# 服务器2: 3/(5+3+2) = 30%
# 服务器3: 2/(5+3+2) = 20%
}

server {
listen 80;
server_name app.example.com;

# 访问日志格式
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;
error_log /var/log/nginx/error.log warn;

location / {
proxy_pass http://backend;

# 重要的代理头部设置
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 X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Port $server_port;

# Cookie 和 Session 相关
proxy_cookie_path / "/; HttpOnly; Secure";
proxy_set_header Cookie $http_cookie;

# 缓冲区优化
proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

# 超时设置
proxy_connect_timeout 60s;
proxy_send_timeout 60s;
proxy_read_timeout 60s;

# 其他优化
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Connection "";
}

# 健康检查端点（可选）
location /health {
access_log off;
return 200 "healthy\\n";
add_header Content-Type text/plain;
}
}
}

3.3 IP哈希算法（IP Hash）

http {
# 基于客户端IP的哈希算法
upstream backend {
ip_hash; # 启用IP哈希算法

server 192.168.1.101:8080;
server 192.168.1.102:8080;
server 192.168.1.103:8080;

# 哈希算法确保同一客户端总是访问同一后端服务器
# 适用于需要会话保持的应用
}

# 或者使用一致性哈希（Nginx Plus 或第三方模块）
upstream backend_consistent {
hash $remote_addr consistent; # 一致性哈希

server 192.168.1.101:8080;
server 192.168.1.102:8080;
server 192.168.1.103:8080;
}

server {
listen 80;

location / {
# 会话保持配置示例
proxy_pass http://backend;

# 会话保持相关头部
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;

# 如果后端使用Sticky Session，可能需要传递特定Cookie
# proxy_set_header Cookie $http_cookie;
}
}
}

3.4 最少连接算法（Least Connections）

http {
upstream backend {
least_conn; # 最少连接算法

server 192.168.1.101:8080;
server 192.168.1.102:8080;
server 192.168.1.103:8080;

# 可以结合权重使用
# server 192.168.1.101:8080 weight=3;
# server 192.168.1.102:8080 weight=2;
}

server {
listen 80;

location / {
proxy_pass http://backend;

# 监控相关配置
proxy_set_header Host $host;

# 连接数监控（需要Nginx status模块）
# stub_status on; # 在server块中启用
}

# Nginx状态监控页面
location /nginx_status {
stub_status on;
access_log off;
allow 192.168.1.0/24; # 只允许内网访问
deny all;
}
}
}

4. 高级负载均衡配置

4.1 健康检查配置

http {
upstream backend {
# 基础服务器配置
server 192.168.1.101:8080 max_fails=3 fail_timeout=30s;
server 192.168.1.102:8080 max_fails=3 fail_timeout=30s;
server 192.168.1.103:8080 max_fails=3 fail_timeout=30s;

# 被动健康检查参数
# max_fails: 最大失败次数
# fail_timeout: 失败后暂停时间

# 对于Nginx Plus或OpenResty，支持主动健康检查
# health_check interval=5s fails=3 passes=2;
# health_check_timeout 3s;
# health_check_status 200;
}

# 自定义健康检查（使用第三方模块或OpenResty）
upstream backend_with_healthcheck {
server 192.168.1.101:8080;
server 192.168.1.102:8080;
server 192.168.1.103:8080;

# 使用nginx_upstream_check_module
check interval=3000 rise=2 fall=3 timeout=1000 type=http;
check_http_send "HEAD /health HTTP/1.0\\r\\n\\r\\n";
check_http_expect_alive http_2xx http_3xx;
}

server {
listen 80;

location / {
proxy_pass http://backend_with_healthcheck;
proxy_set_header Host $host;

# 错误处理
proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
proxy_next_upstream_tries 3;
proxy_next_upstream_timeout 10s;
}

# 健康检查端点
location /upstream_check {
internal; # 只允许内部访问

proxy_pass http://backend;
proxy_set_header Host $host;
}
}
}

4.2 会话保持（Session Persistence）

http {
# 方法1：使用IP哈希（简单但不够精确）
upstream backend_ip_hash {
ip_hash;
server 192.168.1.101:8080;
server 192.168.1.102:8080;
}

# 方法2：使用Cookie（更精确）
upstream backend_sticky {
# 需要nginx-sticky-module模块
sticky cookie srv_id expires=1h domain=.example.com path=/;

server 192.168.1.101:8080;
server 192.168.1.102:8080;
}

# 方法3：使用Nginx Plus的sticky指令
upstream backend_plus {
zone backend_zone 64k;
server 192.168.1.101:8080;
server 192.168.1.102:8080;

# Nginx Plus特有
# sticky cookie srv_id expires=1h;
# or
# sticky route $route_cookie $route_uri;
}

# 方法4：应用层会话保持（推荐）
upstream backend_app {
server 192.168.1.101:8080;
server 192.168.1.102:8080;
}

server {
listen 80;

# 使用Redis等外部存储解决会话问题
location / {
proxy_pass http://backend_app;

# 传递会话Cookie
proxy_set_header Cookie $http_cookie;
proxy_cookie_path / "/; HttpOnly; Secure";

# 或者使用JWT等无状态认证
proxy_set_header Authorization $http_authorization;
}

# 静态资源分离
location ~* \\.(jpg|jpeg|png|gif|ico|css|js)$ {
expires 1y;
add_header Cache-Control "public, immutable";

# 可以使用CDN或独立静态资源服务器
root /var/www/static;
}
}
}

4.3 TCP/UDP 负载均衡

# TCP负载均衡配置（stream模块）
stream {
# 定义上游服务器组
upstream backend_tcp {
# 负载均衡算法
hash $remote_addr consistent; # 一致性哈希

server 192.168.1.101:3306 weight=5; # MySQL主库
server 192.168.1.102:3306 weight=3; # MySQL从库1
server 192.168.1.103:3306 weight=2; # MySQL从库2

# 健康检查（Nginx Plus）
# health_check interval=10s passes=2 fails=3;
}

upstream backend_redis {
server 192.168.1.111:6379; # Redis主节点
server 192.168.1.112:6379; # Redis从节点1
server 192.168.1.113:6379; # Redis从节点2

# Redis哨兵模式负载均衡
# server 192.168.1.114:26379;
# server 192.168.1.115:26379;
}

# TCP服务器配置
server {
listen 3307; # 对外暴露的端口
proxy_pass backend_tcp;

# TCP特定配置
proxy_connect_timeout 5s;
proxy_timeout 3600s;
proxy_buffer_size 16k;

# SSL终止（如果需要）
# ssl on;
# ssl_certificate /path/to/cert.pem;
# ssl_certificate_key /path/to/key.pem;
}

# Redis负载均衡
server {
listen 6380;
proxy_pass backend_redis;

# Redis协议保持
proxy_protocol on;
}

# UDP负载均衡示例（DNS服务器）
upstream dns_servers {
server 192.168.1.201:53; # DNS服务器1
server 192.168.1.202:53; # DNS服务器2
}

server {
listen 53 udp reuseport;
proxy_pass dns_servers;
proxy_timeout 1s;
proxy_responses 1;
}
}

5. 实战：完整的微服务负载均衡配置

5.1 多环境配置管理

# nginx.conf – 主配置文件
user nginx;
worker_processes auto; # 自动根据CPU核心数设置
worker_rlimit_nofile 65535; # 每个worker进程最大文件描述符数

error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;

events {
worker_connections 4096; # 每个worker进程最大连接数
use epoll; # Linux系统使用epoll事件模型
multi_accept on; # 一次接受多个连接
}

http {
include /etc/nginx/mime.types;
default_type application/octet-stream;

# 日志格式
log_format main '$remote_addr – $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" '
'upstream_addr=$upstream_addr '
'upstream_status=$upstream_status '
'request_time=$request_time '
'upstream_response_time=$upstream_response_time';

access_log /var/log/nginx/access.log main buffer=32k flush=5s;

# 基础优化
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
keepalive_requests 1000;
client_max_body_size 10m;
client_body_buffer_size 128k;

# Gzip压缩
gzip on;
gzip_vary on;
gzip_min_length 1024;
gzip_comp_level 6;
gzip_types text/plain text/css text/xml text/javascript
application/json application/javascript application/xml+rss
application/atom+xml image/svg+xml;

# 引入上游服务器配置
include /etc/nginx/conf.d/upstreams/*.conf;

# 引入虚拟主机配置
include /etc/nginx/sites-enabled/*.conf;
}

5.2 上游服务器配置文件

# /etc/nginx/conf.d/upstreams/backend.conf
# 用户服务集群
upstream user_service {
zone user_service_zone 64k;
least_conn;

# 生产环境服务器
server 10.0.1.11:8080 weight=3 max_fails=2 fail_timeout=30s;
server 10.0.1.12:8080 weight=3 max_fails=2 fail_timeout=30s;
server 10.0.1.13:8080 weight=2 max_fails=2 fail_timeout=30s;
server 10.0.1.14:8080 weight=2 max_fails=2 fail_timeout=30s;

# 备份服务器
server 10.0.2.11:8080 backup;

# 会话保持（Nginx Plus）
# sticky cookie srv_id expires=1h domain=.example.com path=/;
}

# 订单服务集群
upstream order_service {
zone order_service_zone 64k;
ip_hash;

server 10.0.1.21:8080;
server 10.0.1.22:8080;
server 10.0.1.23:8080;

# 慢启动（Nginx Plus）
# server 10.0.1.24:8080 slow_start=30s;
}

# 支付服务集群
upstream payment_service {
zone payment_service_zone 64k;

server 10.0.1.31:8080 weight=5;
server 10.0.1.32:8080 weight=5;
server 10.0.1.33:8080 weight=3;
server 10.0.1.34:8080 weight=3;

# 健康检查配置
# health_check interval=5s fails=3 passes=2 uri=/health;
}

# API网关配置
upstream api_gateway {
zone api_gateway_zone 64k;
hash $request_uri consistent;

server 10.0.1.41:8080;
server 10.0.1.42:8080;
server 10.0.1.43:8080;
}

# 静态资源服务器
upstream static_servers {
zone static_servers_zone 64k;

server 10.0.3.11:80;
server 10.0.3.12:80;
server 10.0.3.13:80;

# 文件服务器特定优化
keepalive 32;
}

5.3 虚拟主机配置

# /etc/nginx/sites-enabled/api.example.com.conf
server {
listen 80;
server_name api.example.com;

# SSL配置（推荐启用HTTPS）
listen 443 ssl http2;
ssl_certificate /etc/ssl/certs/api.example.com.crt;
ssl_certificate_key /etc/ssl/private/api.example.com.key;
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512;
ssl_prefer_server_ciphers off;
ssl_session_cache shared:SSL:10m;
ssl_session_timeout 10m;

# 安全头
add_header X-Frame-Options SAMEORIGIN;
add_header X-Content-Type-Options nosniff;
add_header X-XSS-Protection "1; mode=block";
add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

# 限流配置
limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;

# API版本路由
location ~ ^/api/v1/users {
limit_req zone=api_limit burst=20 nodelay;

# 认证检查
auth_request /auth;
auth_request_set $auth_status $upstream_status;

proxy_pass http://user_service;
proxy_set_header X-API-Version v1;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;

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

# 错误处理
proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
proxy_next_upstream_tries 3;

# 缓存设置
proxy_cache api_cache;
proxy_cache_key "$scheme$request_method$host$request_uri";
proxy_cache_valid 200 302 1m;
proxy_cache_valid 404 1m;
proxy_cache_use_stale error timeout updating http_500 http_502 http_503 http_504;
add_header X-Cache-Status $upstream_cache_status;
}

location ~ ^/api/v1/orders {
limit_req zone=api_limit burst=20 nodelay;

proxy_pass http://order_service;
proxy_set_header X-API-Version v1;

# 订单服务特定配置
proxy_set_header X-Session-ID $cookie_sessionid;
proxy_cookie_path / "/; HttpOnly; Secure";
}

location ~ ^/api/v1/payments {
limit_req zone=api_limit burst=10 nodelay;

proxy_pass http://payment_service;
proxy_set_header X-API-Version v1;

# 支付服务需要更长的超时时间
proxy_connect_timeout 10s;
proxy_send_timeout 60s;
proxy_read_timeout 60s;
}

# 认证端点
location = /auth {
internal;
proxy_pass http://auth_service;
proxy_pass_request_body off;
proxy_set_header Content-Length "";
proxy_set_header X-Original-URI $request_uri;
}

# 健康检查端点
location /health {
access_log off;
stub_status on;

# 检查各个上游服务
proxy_pass http://user_service/actuator/health;
proxy_set_header Host $host;
}

# 监控端点
location /metrics {
access_log off;

# Prometheus指标端点
proxy_pass http://monitoring_service:9090;
proxy_set_header Host $host;

allow 10.0.0.0/8; # 只允许内网访问
deny all;
}

# 静态文件
location ~* \\.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
expires 1y;
add_header Cache-Control "public, immutable";

proxy_pass http://static_servers;
proxy_cache static_cache;
proxy_cache_valid 200 302 1y;
proxy_cache_valid 404 1m;
}

# 错误页面
error_page 404 /404.html;
error_page 500 502 503 504 /50x.html;

location = /50x.html {
root /usr/share/nginx/html;
}
}

6. 性能优化与监控

6.1 Nginx 性能调优

# /etc/nginx/nginx.conf – 优化版本
user nginx;
worker_processes auto;
worker_rlimit_nofile 100000; # 提高文件描述符限制

error_log /var/log/nginx/error.log crit;
pid /run/nginx.pid;

events {
worker_connections 65536; # 提高连接数
use epoll;
multi_accept on;
accept_mutex off; # 高并发时关闭锁
}

http {
# 基础优化
sendfile on;
tcp_nopush on;
tcp_nodelay on;
types_hash_max_size 2048;
server_tokens off; # 隐藏Nginx版本

# 连接优化
keepalive_timeout 30;
keepalive_requests 10000;
reset_timedout_connection on;

# 客户端优化
client_body_timeout 10;
client_header_timeout 10;
send_timeout 10;
client_max_body_size 20m;
client_body_buffer_size 256k;

# 缓冲区优化
proxy_buffering on;
proxy_buffer_size 32k;
proxy_buffers 8 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;

# 压缩优化
gzip on;
gzip_vary on;
gzip_min_length 256;
gzip_comp_level 5;
gzip_types *; # 压缩所有类型

# 缓存优化
open_file_cache max=100000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;

# SSL优化
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 1d;
ssl_session_tickets off;
ssl_stapling on;
ssl_stapling_verify on;
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;

# 请求限流
limit_req_zone $binary_remote_addr zone=perip:10m rate=100r/s;
limit_req_zone $server_name zone=perserver:10m rate=1000r/s;

include /etc/nginx/conf.d/*.conf;
}

6.2 监控配置

#!/bin/bash
# monitor_nginx.sh – Nginx监控脚本

# 监控Nginx状态
NGINX_STATUS_URL="http://localhost/nginx_status"

# 检查Nginx是否运行
check_nginx_process() {
if pgrep -x "nginx" > /dev/null; then
echo "✅ Nginx进程运行正常"
return 0
else
echo "❌ Nginx进程未运行"
return 1
fi
}

# 获取Nginx状态信息
get_nginx_status() {
curl -s $NGINX_STATUS_URL | while read line; do
case $line in
Active*)
echo "活跃连接: $(echo $line | awk '{print $3}')"
;;
accepts*)
echo "已接受连接: $(echo $line | awk '{print $2}')"
;;
handled*)
echo "已处理连接: $(echo $line | awk '{print $2}')"
;;
requests*)
echo "总请求数: $(echo $line | awk '{print $2}')"
;;
Reading*)
echo "正在读取的连接: $(echo $line | awk '{print $2}')"
echo "正在写入的连接: $(echo $line | awk '{print $4}')"
echo "空闲连接: $(echo $line | awk '{print $6}')"
;;
esac
done
}

# 检查上游服务器状态
check_upstream_servers() {
echo "=== 上游服务器状态 ==="
# 这里可以使用nginx-module-vts或自定义端点
# 示例：检查各个服务的健康状态
services=("user_service" "order_service" "payment_service")

for service in "${services[@]}"; do
count=$(nginx -t 2>&1 | grep -c "server.*$service")
echo "$service: 配置了 $count 个服务器"
done
}

# 监控日志文件
monitor_error_log() {
echo "=== 错误日志监控 ==="
ERROR_LOG="/var/log/nginx/error.log"

if [ -f "$ERROR_LOG" ]; then
recent_errors=$(tail -100 $ERROR_LOG | grep -E "(error|emerg|crit)" | wc -l)
echo "最近100行中的错误数: $recent_errors"

if [ $recent_errors -gt 10 ]; then
echo "⚠️ 警告: 错误日志中有大量错误"
tail -20 $ERROR_LOG
fi
fi
}

# 主函数
main() {
echo "Nginx负载均衡监控报告"
echo "======================"
echo "时间: $(date)"
echo ""

check_nginx_process
if [ $? -eq 0 ]; then
echo ""
get_nginx_status
echo ""
check_upstream_servers
echo ""
monitor_error_log
fi
}

# 执行监控
main

6.3 Prometheus + Grafana 监控仪表板

# prometheus.yml – Nginx监控配置
global:
scrape_interval: 15s
evaluation_interval: 15s

scrape_configs:
– job_name: 'nginx'
static_configs:
– targets: ['localhost:9113'] # nginx-prometheus-exporter
metrics_path: /metrics
scrape_interval: 10s

– job_name: 'nginx_status'
static_configs:
– targets: ['nginx-host:80']
metrics_path: /nginx_status
params:
format: [prometheus]

– job_name: 'node_exporter'
static_configs:
– targets: ['nginx-host:9100']

# 告警规则
rule_files:
– "nginx_alerts.yml"

# nginx_alerts.yml – 告警规则
groups:
– name: nginx_alerts
rules:
– alert: NginxDown
expr: nginx_up == 0
for: 1m
labels:
severity: critical
annotations:
summary: "Nginx实例下线"
description: "{{ $labels.instance }} 上的Nginx已经下线超过1分钟"

– alert: HighErrorRate
expr: rate(nginx_http_requests_total{status=~"5.."}[5m]) / rate(nginx_http_requests_total[5m]) > 0.05
for: 2m
labels:
severity: warning
annotations:
summary: "高错误率"
description: "{{ $labels.instance }} 的5xx错误率超过5%"

– alert: HighRequestLatency
expr: histogram_quantile(0.95, rate(nginx_http_request_duration_seconds_bucket[5m])) > 1
for: 5m
labels:
severity: warning
annotations:
summary: "高请求延迟"
description: "{{ $labels.instance }} 的95%请求延迟超过1秒"

7. 故障排除与最佳实践

7.1 常见问题排查

#!/bin/bash
# nginx_troubleshoot.sh – Nginx故障排查工具

echo "=== Nginx负载均衡故障排查工具 ==="
echo ""

# 1. 检查Nginx配置
echo "1. 检查Nginx配置语法…"
nginx -t
echo ""

# 2. 检查Nginx进程
echo "2. 检查Nginx进程状态…"
ps aux | grep nginx | grep -v grep
echo ""

# 3. 检查监听端口
echo "3. 检查Nginx监听端口…"
netstat -tlnp | grep nginx
echo ""

# 4. 检查上游服务器连通性
echo "4. 检查上游服务器连通性…"
UPSTREAM_FILE="/etc/nginx/conf.d/upstreams/backend.conf"
if [ -f "$UPSTREAM_FILE" ]; then
echo "找到上游配置: $UPSTREAM_FILE"
grep "server " $UPSTREAM_FILE | while read line; do
host=$(echo $line | awk '{print $2}' | cut -d: -f1)
port=$(echo $line | awk '{print $2}' | cut -d: -f2)
echo -n "检查 $host:$port … "
nc -z -w 3 $host $port && echo "✅ 正常" || echo "❌ 失败"
done
fi
echo ""

# 5. 检查负载均衡状态
echo "5. 检查负载均衡状态…"
if curl -s http://localhost/nginx_status > /dev/null; then
echo "Nginx状态页面可访问"
curl -s http://localhost/nginx_status
else
echo "Nginx状态页面不可访问"
fi
echo ""

# 6. 检查日志文件
echo "6. 检查最近的错误日志…"
tail -20 /var/log/nginx/error.log
echo ""

# 7. 检查系统资源
echo "7. 检查系统资源使用情况…"
echo "内存使用:"
free -h
echo ""
echo "CPU使用:"
top -bn1 | grep "Cpu(s)"
echo ""
echo "连接数统计:"
netstat -an | grep :80 | wc -l

7.2 最佳实践总结

8. 总结

Nginx作为高性能的负载均衡器，在现代Web架构中扮演着至关重要的角色。通过合理的配置和优化，可以实现：

在实际应用中，建议：

• 从简单配置开始，逐步增加复杂度
• 充分测试各种负载均衡算法
• 建立完善的监控和告警体系
• 定期进行性能压测和优化

通过本文的详细讲解和示例代码，相信您已经掌握了Nginx负载均衡的核心概念和实践技能。在实际部署时，请根据具体业务需求进行调整和优化。

扩展阅读：

• Nginx官方文档
• Nginx配置生成器
• Nginx性能调优指南
• 微服务架构下的负载均衡实践

实用工具：

• nginx-config-formatter
• ngxtop – Nginx日志实时监控
• GoAccess – Nginx日志分析工具

希望本文对您理解和实践Nginx负载均衡有所帮助！如有任何问题，欢迎在评论区交流讨论。