第63章：负载均衡

Tue, 24 Mar 2026 13:18:28 +0800

第六十三章：负载均衡

63.1 Nginx 负载均衡

为什么需要负载均衡？

想象一下：一家餐厅只有1个厨师，生意火爆后，1个厨师做不过来，客人等太久。

解决方案：

增加厨师数量（水平扩展）
有人专门负责分配客人到不同厨师（负载均衡器）

graph LR
 A[用户1] --> LB[负载均衡器]
 B[用户2] --> LB
 C[用户3] --> LB
 LB --> S1[服务器1]
 LB --> S2[服务器2]
 LB --> S3[服务器3]

Nginx 负载均衡配置

1
2
3
4
5


# 安装 Nginx
sudo apt install nginx

# 配置负载均衡
sudo nano /etc/nginx/conf.d/upstream.conf

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20


# upstream 定义后端服务器池
upstream backend {
 # 1. 轮询（默认）
 server backend1.example.com;
 server backend2.example.com;
 server backend3.example.com;
}

# 使用 upstream
server {
 listen 80;
 server_name myapp.com;

 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;
 }
}

负载均衡算法

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36


# 1. 轮询（Round Robin）- 默认
upstream backend {
 server 192.168.1.101;
 server 192.168.1.102;
 server 192.168.1.103;
}

# 2. 加权轮询（Weighted Round Robin）
upstream backend {
 server 192.168.1.101 weight=5; # 接收5倍流量
 server 192.168.1.102 weight=3;
 server 192.168.1.103 weight=2;
}

# 3. IP 哈希（IP Hash）- 同一 IP 访问同一服务器
upstream backend {
 ip_hash;
 server 192.168.1.101;
 server 192.168.1.102;
 server 192.168.1.103;
}

# 4. 最少连接（Least Connections）
upstream backend {
 least_conn;
 server 192.168.1.101;
 server 192.168.1.102;
 server 192.168.1.103;
}

# 5. 通用哈希（Hash）
upstream backend {
 hash $request_uri consistent;
 server 192.168.1.101;
 server 192.168.1.102;
}

健康检查

1
2
3
4
5


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

完整配置示例

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41


# /etc/nginx/conf.d/backend.conf

upstream backend_servers {
 least_conn; # 最少连接算法
 
 server 192.168.1.101:8080 weight=5;
 server 192.168.1.102:8080 weight=3;
 server 192.168.1.103:8080 weight=2;
 
 # 保持连接
 keepalive 32;
}

server {
 listen 80;
 server_name myapp.com;

 # 开启 gzip
 gzip on;
 gzip_types text/plain application/json application/javascript text/css;

 location / {
 proxy_pass http://backend_servers;
 
 # 设置请求头
 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;
 
 # 超时设置
 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;
 }
}

HTTPS 配置

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26


server {
 listen 443 ssl http2;
 server_name myapp.com;

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

 ssl_protocols TLSv1.2 TLSv1.3;
 ssl_ciphers HIGH:!aNULL:!MD5;
 ssl_prefer_server_ciphers on;

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

# HTTP 重定向到 HTTPS
server {
 listen 80;
 server_name myapp.com;
 return 301 https://$server_name$request_uri;
}

63.2 HAProxy

HAProxy 是专业的负载均衡器，性能极高，常用于大流量场景。

第十八卷：负载均衡与高可用 on 编程那些事儿

第63章：负载均衡

第六十三章：负载均衡

63.1 Nginx 负载均衡

为什么需要负载均衡？

Nginx 负载均衡配置

负载均衡算法

健康检查

完整配置示例

HTTPS 配置

63.2 HAProxy

第64章：高可用

第六十四章：高可用

64.1 Keepalived

什么是高可用？