我对NodeJS不熟悉，试图在Cloud9 IDE中设置一个已存在的项目（由他人开发），我使用一个旧的Cloud9帐户（因此不在AWS上运行）。我拉取了git并安装了所有内容，这似乎都没有问题。
要在Cloud9之外本地运行该应用程序，您需要使用npm run start命令启动服务器（我知道来自开发该应用程序的人，这对他有效）。但是我想在Cloud9中设置它，在Cloud9中首先必须设置一些变量（如果我不首先定义主机，则会出现“无效的主机标题”错误），因此我使用以下两个命令：
export HOST=$C9_HOSTNAME && export PORT=8080
npm run start
npm run start 命令会出现以下错误：
无法在 appname-username.c9users.io 上找到空闲端口。
网络错误信息：listen EADDRNOTAVAIL 35.189.252.103
根据 https://docs.c9.io/docs/run-an-application 的说明，我相信端口已经设置正确。我还尝试了 8081、8082 和 $PORT 等值，但都没有生效。
有什么办法可以解决 Cloud9 本地预览的问题吗？
以下是 start.js 的部分代码：
const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000;
const HOST = process.env.HOST || '0.0.0.0';
console.log(`1. The host is ${HOST} on port ${DEFAULT_PORT}`); //ADDED
choosePort(HOST, DEFAULT_PORT)
.then(port => {
console.log(`2. The host is ${HOST} on port ${DEFAULT_PORT}`); //ADDED
if (port == null) {
// We have not found a port.
return;
}
const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
const appName = require(paths.appPackageJson).name;
const urls = prepareUrls(protocol, HOST, port);
// Create a webpack compiler that is configured with custom messages.
const compiler = createCompiler(webpack, config, appName, urls, useYarn);
// Load proxy config
const proxySetting = require(paths.appPackageJson).proxy;
const proxyConfig = prepareProxy(proxySetting, paths.appPublic);
// Serve webpack assets generated by the compiler over a web sever.
const serverConfig = createDevServerConfig(
proxyConfig,
urls.lanUrlForConfig
);
const devServer = new WebpackDevServer(compiler, serverConfig);
// Launch WebpackDevServer.
devServer.listen(port, HOST, err => {
if (err) {
return console.log(err);
}
if (isInteractive) {
clearConsole();
}
console.log(chalk.cyan('Starting the development server...\n'));
openBrowser(urls.localUrlForBrowser);
});
})
.catch(err => {
if (err && err.message) {
console.log(err.message);
}
process.exit(1);
});
netstat --listen命令会返回以下信息：
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp6 0 0 [::]:ssh [::]:* LISTEN
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] STREAM LISTENING 1533837857 /home/ubuntu/.c9/6614254/collab.sock
unix 2 [ ACC ] STREAM LISTENING 1533835235 /home/ubuntu/.c9/bridge.socket
unix 2 [ ACC ] STREAM LISTENING 1533836998 /tmp/tmux-1000/cloud92.2
choosePort函数是node模块"react-dev-utils"的一部分，其内容如下：
function choosePort(host, defaultPort) {
return detect(defaultPort, host).then(
port => new Promise(resolve => {
if (port === defaultPort) {
return resolve(port);
}
if (isInteractive) {
clearConsole();
const existingProcess = getProcessForPort(defaultPort);
const question = {
type: 'confirm',
name: 'shouldChangePort',
message: chalk.yellow(
`Something is already running on port ${defaultPort}.` +
`${existingProcess ? ` Probably:\n ${existingProcess}` : ''}`
) + '\n\nWould you like to run the app on another port instead?',
default: true,
};
inquirer.prompt(question).then(answer => {
if (answer.shouldChangePort) {
resolve(port);
} else {
resolve(null);
}
});
} else {
console.log(
chalk.red(`Something is already running on port ${defaultPort}.`)
);
resolve(null);
}
}),
err => {
throw new Error(
chalk.red(`Could not find an open port at ${chalk.bold(host)}.`) +
'\n' +
('Network error message: ' + err.message || err) +
'\n'
);
}
);
}