NodeJS PTY 计时命令

Question

I'm trying to use a node process to kick off an interactive docker session then automate some commands to it:

 var spawn = require('pty.js').spawn; var proc = spawn('docker', [ 'run', '-i', '-t', 'mycontainer' ], { name: 'test', rows: 30, cols: 200, cwd: process.env.HOME, env: process.env }); proc.on('data', function (data) { console.log(data); }); proc.write('cd /tmp'); proc.write('nvm install 0.10\\r'); proc.write('npm install');

This seems to work, the only issue is it seems like it's just writing in all the commands and firing them. I don't seem to have any control over catching the output or errors of individual commands.

I'm curious if there's a better way to approach this?

Answer 1

You can pipe streams to this process, however it is not advised to do so.

const { pipeline } = require('stream');
const { spawn } = require('node-pty')

const proc = spawn('docker', ['run', '--rm', '-ti', 'alpine', '/bin/sh'], {
  name: 'xterm-color',
  cwd: process.env.HOME,
  env: process.env,
  encoding: null,
});

pipeline(process.stdin, proc, (err) => err && console.warn(err.message))
pipeline(proc, process.stdout, (err) => err && console.warn(err.message))

The maintainer have suggested to not use pty in like a stream. It's simply a matter of changing the pipeline for something like this.

(async (stream) => {
  for await (const chunk of stream) {
    proc.write(chunk.toString())
  }
})(process.stdin).catch(console.warn)

The gist is that we should pass string into the write function. We also should expect string as its output. Therefore, we should not set any encoding in the object so that it by default outputs utf8 string.

Regarding your initial question. proc.write('ls\\r') is the correct way of doing it. Note the trailing \\r to virtually press enter. Just like in a normal terminal, when you execute a command, you cannot fire a second one simultaneously. The commands will just queue up and run one after another.

Input:

const { spawn } = require('node-pty')

const proc = spawn('docker', ['run', '--rm', '-ti', '--network=host', 'node', '/bin/sh'], {
  name: 'xterm-color',
  cwd: process.env.HOME,
  env: process.env,
});

proc.write('npm init -y\r')
proc.write('npm i eslint\r')
proc.write('ls node_modules /\r')

const disposable = proc.onData((text) => process.stdout.write(text))

const exitDisposable = proc.onExit(() => {
  disposable.dispose()
  exitDisposable.dispose()
})

Output:

npm i eslint
ls node_modules /
# Wrote to /package.json:

{
  "name": "",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "directories": {
    "lib": "lib"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}


npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN @1.0.0 No description
npm WARN @1.0.0 No repository field.

+ eslint@7.1.0
added 136 packages from 82 contributors and audited 136 packages in 9.461s

9 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

# /:
bin   etc   lib64  node_modules       package.json  run   sys  var
boot  home  media  opt                proc          sbin  tmp
dev   lib   mnt    package-lock.json  root          srv   usr

node_modules:
@babel                      is-extglob
@types                      is-fullwidth-code-point
...
...
# 

You see it wrote ls before npm install was completed but it ran afterwards.

Also note that I used -ti instead of just -t for the docker args.

Answer 2

Looking through the source for the pty.js module, it is clear that your proc.write is really the standard Node net.Socket.write -- https://nodejs.org/api/net.html#net_socket_write_data_encoding_callback

In short, yes, you are just spamming the commands to the socket. You need to wait for each command to finish before executing the next. Thus, you'll need to use the callback parameter of .write to determine when a command has finished and then proceed from there. Something like this may work:

// this is a quick and dirty hack
let cmdcount = 0;

function submitcmd() {
  switch (cmdcount) {
    case 0:
      proc.write('nvm install 0.10\r', 'utf8', submitcmd);
      break;
    case 1:
      proc.write('npm install', 'utf8', submitcmd);
      break;
  }

  cmdcount += 1;
}

proc.write('cd /tmp', 'utf8', submitcmd);