fix(content): harden Docker practice guide

21_case_devops/21.7_practical_examples.md

@@ -557,6 +557,8 @@ client-output-buffer-limit pubsub 32mb 8mb 60
 
 **三层微服务架构示例：**
 
+> 下面示例聚焦服务拓扑、网络、健康检查和资源限制。为便于阅读，密码仍通过环境变量串接；生产环境应改用 Compose secrets、外部密钥系统或云厂商密钥服务，并避免把敏感值写入 `DATABASE_URL` / `REDIS_URL`。
+
 ```yaml
 services:
   # 前端服务
@@ -564,7 +566,6 @@ services:
     build:
       context: ./frontend
       dockerfile: Dockerfile
-    container_name: frontend
     ports:
       - "3000:3000"
     environment:
@@ -586,7 +587,6 @@ services:
     build:
       context: ./api
       dockerfile: Dockerfile
-    container_name: api
     ports:
       - "8000:8000"
     environment:
@@ -619,7 +619,6 @@ services:
   # PostgreSQL 数据库
   postgres:
     image: postgres:16-alpine
-    container_name: postgres
     environment:
       POSTGRES_DB: myappdb
       POSTGRES_USER: appuser
@@ -641,7 +640,6 @@ services:
   # Redis 缓存
   redis:
     image: redis:8-alpine
-    container_name: redis
     command: ["sh", "-c", "redis-server --appendonly yes --requirepass \"$$REDIS_PASSWORD\""]
     environment:
       REDIS_PASSWORD: ${REDIS_PASSWORD:?set REDIS_PASSWORD}
@@ -659,7 +657,6 @@ services:
   # Nginx 反向代理
   nginx:
     image: nginx:alpine
-    container_name: nginx
     ports:
       - "80:80"
       - "443:443"