load-balancer

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Load Balancer Configuration

负载均衡器配置

Quick Start

快速开始

Configure nginx to distribute traffic across multiple backend servers with health checks and automatic failover.

配置Nginx以在多台后端服务器间分发流量，并具备健康检查和自动故障转移功能。

Instructions

操作步骤

Step 1: Define upstream block

步骤1：定义上游服务器块

Create an upstream block with your backend servers:

nginx

upstream backend {
    # Load balancing method (optional, defaults to round-robin)
    least_conn;  # or ip_hash, or omit for round-robin
    
    # Backend servers
    server backend1.example.com:8080 weight=3;
    server backend2.example.com:8080 weight=2;
    server backend3.example.com:8080;
    
    # Backup server (used when all primary servers are down)
    server backup.example.com:8080 backup;
    
    # Health check parameters
    keepalive 32;
}

创建包含你的后端服务器的上游服务器块：

nginx

upstream backend {
    # Load balancing method (optional, defaults to round-robin)
    least_conn;  # or ip_hash, or omit for round-robin
    
    # Backend servers
    server backend1.example.com:8080 weight=3;
    server backend2.example.com:8080 weight=2;
    server backend3.example.com:8080;
    
    # Backup server (used when all primary servers are down)
    server backup.example.com:8080 backup;
    
    # Health check parameters
    keepalive 32;
}

Step 2: Configure proxy in server block

步骤2：在服务器块中配置代理

Add proxy configuration to route traffic to the upstream:

nginx

server {
    listen 80;
    server_name example.com;
    
    location / {
        proxy_pass http://backend;
        
        # Essential proxy headers
        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;
        
        # Timeouts
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
        
        # Buffering
        proxy_buffering on;
        proxy_buffer_size 4k;
        proxy_buffers 8 4k;
    }
}

添加代理配置以将流量路由到上游服务器：

nginx

server {
    listen 80;
    server_name example.com;
    
    location / {
        proxy_pass http://backend;
        
        # Essential proxy headers
        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;
        
        # Timeouts
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
        
        # Buffering
        proxy_buffering on;
        proxy_buffer_size 4k;
        proxy_buffers 8 4k;
    }
}

Step 3: Add health checks

步骤3：添加健康检查

Configure passive health checks (active checks require nginx Plus):

nginx

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

Parameters:

```
max_fails
```
: Number of failed attempts before marking server as unavailable
```
fail_timeout
```
: Time to wait before retrying a failed server

配置被动健康检查（主动检查需要Nginx Plus）：

nginx

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

参数说明：

```
max_fails
```
: 将服务器标记为不可用之前的失败尝试次数
```
fail_timeout
```
: 重试失败服务器前的等待时间

Step 4: Test and reload

步骤4：测试并重新加载配置

bash

undefined

bash

undefined

Test configuration

nginx -t

Reload nginx

nginx -s reload

undefined

nginx -s reload

undefined

Load Balancing Methods

负载均衡算法

Round-robin (default): Distributes requests evenly across servers

nginx

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

Least connections: Routes to server with fewest active connections

nginx

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

IP hash: Routes same client IP to same server (session persistence)

nginx

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

Weighted: Distributes based on server capacity

nginx

upstream backend {
    server backend1.example.com:8080 weight=3;  # Gets 3x traffic
    server backend2.example.com:8080 weight=1;
}

轮询（默认）：在服务器间均匀分发请求

nginx

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

最少连接数：将请求路由到活跃连接数最少的服务器

nginx

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

IP哈希：将同一客户端IP的请求路由到同一服务器（会话持久化）

nginx

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

加权轮询：根据服务器容量分发流量

nginx

upstream backend {
    server backend1.example.com:8080 weight=3;  # Gets 3x traffic
    server backend2.example.com:8080 weight=1;
}

Common Patterns

常见配置模式

WebSocket proxying

WebSocket代理

nginx

location /ws {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
}

nginx

location /ws {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
}

Sticky sessions with cookie

基于Cookie的粘性会话

nginx

upstream backend {
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    
    # Requires nginx Plus or third-party module
    sticky cookie srv_id expires=1h domain=.example.com path=/;
}

nginx

upstream backend {
    server backend1.example.com:8080;
    server backend2.example.com:8080;
    
    # Requires nginx Plus or third-party module
    sticky cookie srv_id expires=1h domain=.example.com path=/;
}

Slow start (nginx Plus)

慢启动（Nginx Plus）

nginx

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

nginx

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

Advanced

高级配置

For detailed information, see:

Upstream Patterns - Advanced load balancing algorithms and patterns
Health Checks - Comprehensive health check configuration
Caching - Proxy caching strategies for load-balanced backends

如需详细信息，请参阅：

上游服务器模式 - 高级负载均衡算法与模式
健康检查 - 全面的健康检查配置
缓存 - 负载均衡后端的代理缓存策略