设置代理服务器

Nginx 可以作为代理服务器，将客户端请求转发到后端服务器，实现负载均衡、缓存等功能。

基本代理配置

简单代理

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://127.0.0.1:8080;
    }
}

完整代理配置

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://127.0.0.1:8080;
        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;
    }
}

代理指令说明

常用请求头

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;

负载均衡

定义上游服务器

upstream backend {
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    server backend3.example.com:8080;
}

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://backend;
    }
}

负载均衡方法

轮询（默认）

upstream backend {
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    server backend3.example.com:8080;
}

最少连接

upstream backend {
    least_conn;
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    server backend3.example.com:8080;
}

IP 哈希

upstream backend {
    ip_hash;
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    server backend3.example.com:8080;
}

加权轮询

upstream backend {
    server backend1.example.com:8080 weight=5;
    server backend2.example.com:8080;
    server backend3.example.com:8080;
}

服务器参数

upstream backend {
    server backend1.example.com:8080 weight=5;
    server backend2.example.com:8080 max_fails=3 fail_timeout=30s;
    server backend3.example.com:8080 backup;
}

健康检查

主动健康检查（需要商业版）

upstream backend {
    zone backend 64k;
    server backend1.example.com:8080;
    server backend2.example.com:8080;
}

server {
    location / {
        proxy_pass http://backend;
        health_check;
    }
}

被动健康检查

upstream backend {
    server backend1.example.com:8080 max_fails=3 fail_timeout=30s;
    server backend2.example.com:8080 max_fails=3 fail_timeout=30s;
}

缓存配置

定义缓存路径

proxy_cache_path /path/to/cache levels=1:2 keys_zone=my_cache:10m max_size=10g inactive=60m use_temp_path=off;

server {
    location / {
        proxy_cache my_cache;
        proxy_pass http://backend;
    }
}

缓存指令

location / {
    proxy_cache my_cache;
    proxy_cache_valid 200 302 10m;
    proxy_cache_valid 404 1m;
    proxy_cache_key "$scheme$request_method$host$request_uri";
    proxy_cache_bypass $http_cache_control;
    add_header X-Cache-Status $upstream_cache_status;
    proxy_pass http://backend;
}

HTTPS 代理

代理到 HTTPS 后端

location / {
    proxy_pass https://backend;
}

代理到 HTTP 后端（前端 HTTPS）

server {
    listen       443 ssl;
    server_name  localhost;

    ssl_certificate      /etc/ssl/certs/server.crt;
    ssl_certificate_key  /etc/ssl/private/server.key;

    location / {
        proxy_pass http://backend;
        proxy_set_header X-Forwarded-Proto https;
    }
}

WebSocket 代理

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}

upstream websocket {
    server 127.0.0.1:8000;
}

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://websocket;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
    }
}

代理超时设置

location / {
    proxy_pass http://backend;
    proxy_connect_timeout 60s;
    proxy_send_timeout 60s;
    proxy_read_timeout 60s;
}

缓冲区设置

location / {
    proxy_pass http://backend;
    proxy_buffering on;
    proxy_buffer_size 4k;
    proxy_buffers 8 4k;
    proxy_busy_buffers_size 8k;
}

完整配置示例

基本代理服务器

http {
    upstream backend {
        server backend1.example.com:8080;
        server backend2.example.com:8080;
        server backend3.example.com:8080;
    }

    server {
        listen       80;
        server_name  localhost;

        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;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
    }
}

高级代理服务器

http {
    # 缓存配置
    proxy_cache_path /var/cache/nginx/proxy levels=1:2 keys_zone=proxy_cache:10m max_size=100m inactive=60m;

    # 上游服务器
    upstream backend {
        least_conn;
        server backend1.example.com:8080 weight=5;
        server backend2.example.com:8080 max_fails=3 fail_timeout=30s;
        server backend3.example.com:8080 backup;
        keepalive 32;
    }

    server {
        listen       80;
        server_name  localhost;

        # 代理配置
        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;
            proxy_set_header X-Forwarded-Proto $scheme;

            # 缓存
            proxy_cache proxy_cache;
            proxy_cache_valid 200 302 10m;
            proxy_cache_valid 404 1m;
            proxy_cache_key "$scheme$request_method$host$request_uri";
            add_header X-Cache-Status $upstream_cache_status;

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

            # 缓冲
            proxy_buffering on;
            proxy_buffer_size 4k;
            proxy_buffers 8 4k;
        }

        # 健康检查
        location /health {
            proxy_pass http://backend/health;
            access_log off;
        }
    }
}

测试配置

# 测试配置
sudo nginx -t

# 重新加载配置
sudo nginx -s reload

验证代理

# 测试代理
curl -H "Host: example.com" http://localhost/

# 查看响应头
curl -I http://localhost/

# 查看缓存状态
curl -I http://localhost/ | grep X-Cache-Status

最佳实践

1. 使用 upstream：方便管理和扩展
2. 设置超时：避免长时间等待
3. 启用缓存：提高性能
4. 健康检查：确保后端可用
5. 负载均衡：分担服务器压力
6. 监控日志：及时发现异常