// 伪代码示例：信号处理流程
void signal_handler(int sig) {
    switch(sig) {
        case SIGTERM:
            // 执行优雅停机：
            // 1. 停止接收新请求
            // 2. 完成当前处理中的请求
            // 3. 关闭数据连接
            // 4. 释放资源
            // 5. 正常退出
            graceful_shutdown();
            exit(0);
            break;

        case SIGKILL:
            // 无法捕获，操作系统直接终止进程
            break;
    }
}

STOPSIGNAL <signal>

# <signal> 可以是：
# - 信号名称（如 SIGINT、SIGTERM、SIGQUIT）
# - 无符号数字（如 2、3、15）

示例：
STOPSIGNAL SIGINT
STOPSIGNAL 2

{
  "process": {
    "user": {...},
    "args": [...],
    "env": [...],
    ...
  },
  "root": {...},
  "mounts": [...],
  ...
  "stopSignal": "SIGINT"  // 自定义停止信号
}

{
  "containerDefinitions": [
    {
      "name": "web-app",
      "image": "nginx:latest",
      "stopTimeout": 120,
      ...
    }
  ],
  "requiresCompatibilities": ["FARGATE"],
  ...
}

FROM nginx:alpine

# Nginx 默认行为：SIGTERM 立即退出
# 如需优雅停机，改用 SIGQUIT
STOPSIGNAL SIGQUIT

# 或自定义中间件
STOPSIGNAL SIGUSR1

CMD ["nginx", "-g", "daemon off;"]

FROM nginx:alpine

# 使用 SIGQUIT 实现优雅停机
STOPSIGNAL SIGQUIT

# 确保工作进程能以优雅模式关闭
RUN echo "worker_shutdown_timeout 30s;" >> /etc/nginx/nginx.conf

EXPOSE 80

import org.springframework.stereotype.Component;
import javax.annotation.PreDestroy;

@Component
public class GracefulShutdownHandler {

    @PreDestroy
    public void onDestroy() {
        // Spring 管理的优雅停机
        System.out.println("Executing graceful shutdown...");
    }
}

// 或使用 ShutdownHook
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
    System.out.println("Shutdown hook triggered");
    // 执行清理操作
}));

FROM openjdk:11-jre-slim

WORKDIR /app
COPY target/myapp.jar app.jar

# Spring Boot 默认处理 SIGTERM，无需更改
STOPSIGNAL SIGTERM

# 增加停机超时时间
ENV SPRING_LIFECYCLE_TIMEOUT_PER_SHUTDOWN_PHASE=30s

CMD ["java", "-jar", "app.jar"]

const { Consumer } = require('sqs-consumer');
const consumer = Consumer.create({
  queueUrl: 'https://sqs.ap-northeast-1.amazonaws.com/*.fifo',
  handleMessage: async (message) => {
    // 消息处理逻辑
  }
});

let isShuttingDown = false;

// 使用 SIGTERM 处理优雅停机
process.on('SIGTERM', async () => {
  if (isShuttingDown) return;

  isShuttingDown = true;
  console.log('Starting graceful shutdown...');

  // 1. 停止接收新消息
  consumer.stop();

  // 2. 等待当前处理完成
  await waitForCurrentMessagesToComplete();

  // 3. 关闭连接
  await closeConnections();

  console.log('Graceful shutdown complete');
  process.exit(0);
});

consumer.start();

import signal
import sys
import psycopg2.pool
from contextlib import contextmanager

# 创建数据库连接池
db_pool = psycopg2.pool.ThreadedConnectionPool(
    minconn=1, maxconn=10,
    host='db-host', database='mydb'
)

# 优雅停机标志
shutdown_in_progress = False

def graceful_shutdown(signum, frame):
    global shutdown_in_progress

    if shutdown_in_progress:
        return

    shutdown_in_progress = True
    print("Initiating graceful shutdown...")

    # 1. 设置只读模式或拒绝新请求
    set_read_only_mode()

    # 2. 等待活动事务完成
    wait_for_active_transactions()

    # 3. 关闭连接池
    db_pool.close_all()

    print("Shutdown complete")
    sys.exit(0)

# 注册信号处理器
signal.signal(signal.SIGTERM, graceful_shutdown)

# 或使用 STOPSIGNAL SIGUSR2
signal.signal(signal.SIGUSR2, graceful_shutdown)

process.on('SIGTERM', () => {
    // 应用层处理逻辑
    cleanupAndExit();
});

#!/bin/bash
# 传统 wrapper 脚本示例

trap 'nginx -s quit' SIGTERM  # 将 SIGTERM 转换为 SIGQUIT

nginx -g 'daemon off;' &
wait $!  # 等待 nginx 进程

FROM nginx:alpine
STOPSIGNAL SIGQUIT  # 一行配置解决问题

# 同一镜像在多种环境中行为一致

# Kubernetes
kubectl delete pod myapp  # 发送 STOPSIGNAL

# Docker
docker stop myapp  # 发送 STOPSIGNAL

# ECS Fargate
aws ecs stop-task ...  # 发送 STOPSIGNAL

# 设置合理的超时时间
STOPSIGNAL SIGTERM

# 配合 stopTimeout 使用
# ECS 任务定义: stopTimeout: 60

# 使用 docker 验证
$ docker build -t myapp .

# 启动容器
docker run -d --name test myapp

# 停止并验证
$ time docker stop test
real: 12.3s  # 观察是否符合预期耗时

# 查看日志
$ docker logs test
[INFO] SIGQUIT received, starting graceful shutdown...
[INFO] Waiting for 10 active connections to complete...
[INFO] All connections closed, exiting cleanly

# 部署任务
$ aws ecs run-task --cluster prod --task-definition myapp:1

# 监控 CloudWatch Logs
$ aws logs tail /ecs/myapp --follow

# 停止任务并观察
$ aws ecs stop-task --cluster prod --task <task-id>

# 验证日志显示优雅停机

process.on('SIGTERM', () => {
    console.log(`[${new Date().toISOString()}] SIGTERM received`);
    console.log(`[INFO] Active connections: ${getActiveConnectionCount()}`);
    console.log(`[INFO] Pending transactions: ${getPendingTransactionCount()}`);

    const startTime = Date.now();

    gracefulShutdown(() => {
        const duration = Date.now() - startTime;
        console.log(`[${new Date().toISOString()}] Graceful shutdown complete`);
        console.log(`[METRICS] Shutdown duration: ${duration}ms`);
        process.exit(0);
    });
});

# 未来可能的 Lambda 容器支持
Description: Container-based Lambda
Container:
  Image: myapp:latest
  StopSignal: SIGUSR1
  GracefulTimeout: 30

# Nginx
FROM nginx:alpine
STOPSIGNAL SIGQUIT  # 优雅关闭活跃连接

# Apache
FROM httpd:2.4
STOPSIGNAL SIGWINCH  # 优雅停止子进程

# Node.js
FROM node:18-alpine
STOPSIGNAL SIGTERM  # 配合进程监听器使用

# Java Spring Boot
FROM openjdk:11
STOPSIGNAL SIGTERM  # JVM 已优化处理

# Python
FROM python:3.9
STOPSIGNAL SIGTERM  # 配合 signal 模块使用

# PostgreSQL
FROM postgres:13
STOPSIGNAL SIGINT  # 快速检查点然后退出

# Redis
FROM redis:6
STOPSIGNAL SIGTERM  # 数据持久化后退出

# RabbitMQ
FROM rabbitmq:3-management
STOPSIGNAL SIGTERM  # 等待连接关闭

# Kafka
FROM confluentinc/cp-kafka
STOPSIGNAL SIGTERM  # 配合 controlled.shutdown.enable=true