流式输出

本指南说明如何处理来自命令、进程和代码执行的实时输出。

何时使用流式输出

在以下场景使用流式输出：

实时反馈 - 随进度即时展示
长时间运行的操作 - 构建、测试、安装等耗时任务
交互式应用 - 聊天机器人、代码执行、现场演示
大量输出 - 增量处理输出，而不是一次性获取全部
用户体验 - 避免用户在无反馈的情况下等待

对以下场景使用非流式（exec()）：

快速操作 - 几秒内完成的命令
少量输出 - 输出可以轻松放入内存
后处理 - 需要完整输出后再处理

流式执行命令

使用 execStream() 获取实时输出：

import { getSandbox, parseSSEStream } from "@cloudflare/sandbox";

const sandbox = getSandbox(env.Sandbox, "my-sandbox");

const stream = await sandbox.execStream("npm run build");

for await (const event of parseSSEStream(stream)) {
	switch (event.type) {
		case "stdout":
			console.log(event.data);
			break;

		case "stderr":
			console.error(event.data);
			break;

		case "complete":
			console.log("Exit code:", event.exitCode);
			break;

		case "error":
			console.error("Failed:", event.error);
			break;
	}
}

import { getSandbox, parseSSEStream, type ExecEvent } from '@cloudflare/sandbox';

const sandbox = getSandbox(env.Sandbox, 'my-sandbox');

const stream = await sandbox.execStream('npm run build');

for await (const event of parseSSEStream<ExecEvent>(stream)) {
  switch (event.type) {
    case 'stdout':
      console.log(event.data);
      break;

    case 'stderr':
      console.error(event.data);
      break;

    case 'complete':
      console.log('Exit code:', event.exitCode);
      break;

    case 'error':
      console.error('Failed:', event.error);
      break;
  }
}

流式返回给客户端

通过 Server-Sent Events 将流式输出返回给用户：

import { getSandbox } from "@cloudflare/sandbox";

export { Sandbox } from "@cloudflare/sandbox";

export default {
	async fetch(request, env) {
		const sandbox = getSandbox(env.Sandbox, "builder");

		const stream = await sandbox.execStream("npm run build");

		return new Response(stream, {
			headers: {
				"Content-Type": "text/event-stream",
				"Cache-Control": "no-cache",
			},
		});
	},
};

import { getSandbox } from '@cloudflare/sandbox';

export { Sandbox } from '@cloudflare/sandbox';

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const sandbox = getSandbox(env.Sandbox, 'builder');

    const stream = await sandbox.execStream('npm run build');

    return new Response(stream, {
      headers: {
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache'
      }
    });
  }
};

客户端消费：

// Browser JavaScript
const eventSource = new EventSource("/build");

eventSource.addEventListener("stdout", (event) => {
	const data = JSON.parse(event.data);
	console.log(data.data);
});

eventSource.addEventListener("complete", (event) => {
	const data = JSON.parse(event.data);
	console.log("Exit code:", data.exitCode);
	eventSource.close();
});

// Browser JavaScript
const eventSource = new EventSource('/build');

eventSource.addEventListener('stdout', (event) => {
  const data = JSON.parse(event.data);
  console.log(data.data);
});

eventSource.addEventListener('complete', (event) => {
  const data = JSON.parse(event.data);
  console.log('Exit code:', data.exitCode);
  eventSource.close();
});

流式进程日志

监控后台进程输出：

import { parseSSEStream } from "@cloudflare/sandbox";

const process = await sandbox.startProcess("node server.js");

const logStream = await sandbox.streamProcessLogs(process.id);

for await (const log of parseSSEStream(logStream)) {
	console.log(log.data);

	if (log.data.includes("Server listening")) {
		console.log("Server is ready");
		break;
	}
}

import { parseSSEStream, type LogEvent } from '@cloudflare/sandbox';

const process = await sandbox.startProcess('node server.js');

const logStream = await sandbox.streamProcessLogs(process.id);

for await (const log of parseSSEStream<LogEvent>(logStream)) {
  console.log(log.data);

  if (log.data.includes('Server listening')) {
    console.log('Server is ready');
    break;
  }
}

处理错误

检查退出码并处理流错误：

const stream = await sandbox.execStream("npm run build");

for await (const event of parseSSEStream(stream)) {
	switch (event.type) {
		case "stdout":
			console.log(event.data);
			break;

		case "error":
			throw new Error(`Build failed: ${event.error}`);

		case "complete":
			if (event.exitCode !== 0) {
				throw new Error(`Build failed with exit code ${event.exitCode}`);
			}
			break;
	}
}

const stream = await sandbox.execStream('npm run build');

for await (const event of parseSSEStream<ExecEvent>(stream)) {
  switch (event.type) {
    case 'stdout':
      console.log(event.data);
      break;

    case 'error':
      throw new Error(`Build failed: ${event.error}`);

    case 'complete':
      if (event.exitCode !== 0) {
        throw new Error(`Build failed with exit code ${event.exitCode}`);
      }
      break;
  }
}

最佳实践

始终消费流 - 不要让流挂起而不消费
处理所有事件类型 - 处理 stdout、stderr、complete 和 error 事件
检查退出码 - 非零退出码表示失败
提供反馈 - 对长时间操作向用户展示进度

何时使用流式输出

流式执行命令

流式返回给客户端

流式进程日志

处理错误

最佳实践

相关资源