301 lines
7.2 KiB
Markdown
301 lines
7.2 KiB
Markdown
# 多实例与负载均衡
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:::tip 说明
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当单台服务器无法满足性能需求时，需要通过多实例部署和负载均衡来提升系统吞吐量。本文介绍本项目的水平扩展方案。
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:::
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## Gunicorn 多 Worker 配置
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### Worker 数量计算
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```python
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# gunicorn.conf.py
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import multiprocessing
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# 推荐公式：CPU 核心数 * 2 + 1
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workers = multiprocessing.cpu_count() * 2 + 1
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# Worker 类型
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worker_class = 'gevent' # 异步 Worker，适合 I/O 密集型
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# 超时时间
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timeout = 120
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# 最大请求数（防止内存泄漏）
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max_requests = 1000
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max_requests_jitter = 50
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# 绑定地址
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bind = '127.0.0.1:8000'
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```
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### Worker 类型选择
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| 类型 | 说明 | 适用场景 |
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|------|------|---------|
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| `sync` | 同步 Worker（默认） | CPU 密集型 |
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| `gevent` | 异步 Worker | I/O 密集型（推荐） |
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| `uvicorn` | ASGI Worker | 异步框架 |
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## Nginx 负载均衡
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### 基础配置
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```nginx
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http {
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upstream djangoadmin {
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# 轮询策略（默认）
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server 127.0.0.1:8001;
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server 127.0.0.1:8002;
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server 127.0.0.1:8003;
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}
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server {
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listen 80;
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server_name your-domain.com;
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# 前端静态文件
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root /opt/project/ui/dist;
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index index.html;
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location / {
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try_files $uri $uri/ /index.html;
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}
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# 后端 API 负载均衡
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location /api/ {
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proxy_pass http://djangoadmin;
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proxy_set_header Host $host;
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proxy_set_header X-Real-IP $remote_addr;
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proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
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proxy_set_header X-Forwarded-Proto $scheme;
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}
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}
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}
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```
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### 负载均衡策略
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| 策略 | 配置 | 说明 |
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|------|------|------|
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| 轮询 | 默认 | 依次分配请求 |
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| 权重 | `weight=3` | 按权重分配 |
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| IP Hash | `ip_hash` | 同一 IP 固定到同一后端 |
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| 最少连接 | `least_conn` | 分配到连接数最少的后端 |
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```nginx
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upstream djangoadmin {
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# 权重策略：服务器配置不同按权重分配
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server 127.0.0.1:8001 weight=3;
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server 127.0.0.1:8002 weight=2;
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server 127.0.0.1:8003 weight=1;
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# IP Hash：需要 Session 粘性时使用
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# ip_hash;
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# 最少连接
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# least_conn;
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# 健康检查
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server 127.0.0.1:8001 max_fails=3 fail_timeout=30s;
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}
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```
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## JWT 无状态认证
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项目使用 JWT 认证，天然支持多实例部署：
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```
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用户请求 → Nginx → 任意后端实例 → 验证 JWT → 返回响应
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```
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### 为什么 JWT 适合多实例
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```
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1. 无状态：Token 自包含用户信息，无需服务端 Session
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2. 无需共享存储：不需要 Redis 共享 Session
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3. 任意路由：请求可以发到任意后端实例
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4. 水平扩展：增加实例即可提升性能
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```
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:::warning Token 黑名单
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退出登录时 Token 加入 Redis 黑名单。多实例部署时，所有实例必须连接同一个 Redis，否则 Token 黑名单不生效。
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:::
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## 文件存储共享
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多实例部署时，上传的文件需要所有实例都能访问：
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### 方案 1：NFS 共享存储
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```bash
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# 服务器挂载 NFS
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mount -t nfs storage-server:/data/uploads /opt/project/public/uploads
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```
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### 方案 2：对象存储（推荐）
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使用 OSS/S3/MinIO 等对象存储：
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```python
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# 配置对象存储
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DEFAULT_FILE_STORAGE = 'storages.backends.s3boto3.S3Boto3Storage'
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AWS_STORAGE_BUCKET_NAME = 'djangoadmin'
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AWS_S3_ENDPOINT_URL = 'http://minio:9000'
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```
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### 方案 3：分布式文件系统
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使用 Ceph、GlusterFS 等分布式文件系统。
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## Redis 高可用
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多实例部署时，Redis 是关键的共享存储：
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### Redis Sentinel
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```python
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# 配置 Redis Sentinel
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CACHES = {
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'default': {
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'BACKEND': 'django_redis.cache.RedisCache',
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'LOCATION': 'redis://sentinel1:26379;redis://sentinel2:26379;redis://sentinel3:26379',
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'OPTIONS': {
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'CLIENT_CLASS': 'django_redis.client.SentinelClient',
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'SENTINEL_KWARGS': {'sentinel_kwargs': {'password': 'sentinel_password'}},
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'PASSWORD': 'redis_password',
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}
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}
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}
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```
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### Redis Cluster
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```python
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# 配置 Redis Cluster
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CACHES = {
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'default': {
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'BACKEND': 'django_redis.cache.RedisCache',
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'LOCATION': [
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'redis://node1:6379',
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'redis://node2:6379',
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'redis://node3:6379',
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],
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'OPTIONS': {
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'CLIENT_CLASS': 'django_redis.client.ClusterClient',
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}
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}
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}
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```
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## 数据库读写分离
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### Django 配置
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```python
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# application/settings.py
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DATABASES = {
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'default': { # 主库（写）
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'ENGINE': 'django.db.backends.mysql',
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'HOST': 'master-db',
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'PORT': 3306,
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'NAME': 'djangoadmin',
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'USER': 'root',
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'PASSWORD': 'password',
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},
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'replica': { # 从库（读）
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'ENGINE': 'django.db.backends.mysql',
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'HOST': 'replica-db',
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'PORT': 3306,
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'NAME': 'djangoadmin',
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'USER': 'root',
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'PASSWORD': 'password',
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},
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}
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# 数据库路由
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DATABASE_ROUTERS = ['config.db_router.MasterSlaveRouter']
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```
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### 数据库路由
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```python
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# config/db_router.py
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class MasterSlaveRouter:
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"""主从数据库路由"""
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def db_for_read(self, model, **hints):
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return 'replica'
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def db_for_write(self, model, **hints):
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return 'default'
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def allow_relation(self, obj1, obj2, **hints):
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return True
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def allow_migrate(self, db, app_label, model_name=None, **hints):
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return db == 'default'
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```
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## Supervisor 多实例配置
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```bash
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; /etc/supervisor/conf.d/djangoadmin.conf
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[program:djangoadmin-1]
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command=/opt/venv/bin/gunicorn application.wsgi:application -c gunicorn.conf.py -b 127.0.0.1:8001
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directory=/opt/project
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user=www-data
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autostart=true
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autorestart=true
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stdout_logfile=/var/log/djangoadmin/worker-1.log
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[program:djangoadmin-2]
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command=/opt/venv/bin/gunicorn application.wsgi:application -c gunicorn.conf.py -b 127.0.0.1:8002
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directory=/opt/project
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user=www-data
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autostart=true
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autorestart=true
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stdout_logfile=/var/log/djangoadmin/worker-2.log
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[program:djangoadmin-3]
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command=/opt/venv/bin/gunicorn application.wsgi:application -c gunicorn.conf.py -b 127.0.0.1:8003
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directory=/opt/project
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user=www-data
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autostart=true
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autorestart=true
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stdout_logfile=/var/log/djangoadmin/worker-3.log
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[group:djangoadmin]
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programs=djangoadmin-1,djangoadmin-2,djangoadmin-3
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```
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## 健康检查
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Nginx 负载均衡需要健康检查来自动剔除故障节点：
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```nginx
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upstream djangoadmin {
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server 127.0.0.1:8001 max_fails=3 fail_timeout=30s;
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server 127.0.0.1:8002 max_fails=3 fail_timeout=30s;
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server 127.0.0.1:8003 max_fails=3 fail_timeout=30s;
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}
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```
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### 健康检查端点
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```python
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# application/health/views.py
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def health_check(request):
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"""健康检查端点"""
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try:
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with connection.cursor() as cursor:
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cursor.execute("SELECT 1")
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return JsonResponse({"status": "healthy"})
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except Exception as e:
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return JsonResponse({"status": "unhealthy", "error": str(e)}, status=503)
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```
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## 总结
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多实例与负载均衡方案涵盖 Gunicorn 多 Worker、Nginx 负载均衡、JWT 无状态认证、文件存储共享、Redis 高可用、数据库读写分离、Supervisor 多实例配置、健康检查等方面。核心原则：无状态应用 + 共享存储 + 负载均衡。
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