child_process.spawn produces empty string for various commands (node, npm, ncu)

[kleinfreund]

• Version: v12.1.0, v13.1.0, v13.12.0, v14.10.1, v15.6.0
• Platform: Linux RAUMSTATION 5.0.0-13-generic 14-Ubuntu SMP Mon Apr 15 14:59:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
• Subsystem: child process (?)

I switched from the PPA binary (https://github.com/nodesource/distributions/blob/master/README.md#debinstall) to the snap binary (https://snapcraft.io/node). This started to break the ncu -g command. Originally, I opened an issue with npm-check-updates, but it doesn’t seem to be an issue on their end (for reference: raineorshine/npm-check-updates#536).

Only with the snap binary do I get the following error:

/home/phil/.npm-global/lib/node_modules/npm-check-updates/lib/npm-check-updates.js:387
        throw err;
        ^

Error: Expected JSON from "npm ls". This could be due to npm instability.


    at parseJson (/home/phil/.npm-global/lib/node_modules/npm-check-updates/lib/package-managers/npm.js:38:15)
    at /home/phil/.npm-global/lib/node_modules/npm-check-updates/lib/package-managers/npm.js:144:30
    at processTicksAndRejections (internal/process/task_queues.js:89:5)

The command that is executed with child_process.spawn is npm ls --global --depth=0 --json which produces the correct JSON with both the PPA and the snap binary when executed directly from the terminal.

Steps to reproduce:

Create a reproduction.js file containing the following code and run node reproduction.js with node being a Node.js binary from a Snap source (reproduces with all versions from v12 to v14 at least).

const { spawnSync } = require('child_process')

// Both these spawn commands will yield nothing in their stdout.
// The latter should just contain a Node version tring such as `v14.10.1`.

// npm ls --global --depth=0 --json
const npmListOutput = String(spawnSync('npm', ['ls', '--global', '--depth=0', '--json']).stdout)
console.log({ npmListOutput });

// node --version
const nodeVersionOutput = String(spawnSync('node', ['--version']).stdout)
console.log({ nodeVersionOutput });

To switch around the Node binary on Ubuntu:

1. Uninstall Node.

   sudo apt remove nodejs
   

2. Install Node via Snap.

   sudo snap install node --channel=14/stable --classic
   

3. Verify that Snap’s Node is used (i.e. on my system, the binary is reported to be in /snap/bin/node when running which node).

4. Run npm-check-updates with the global flag.

   ncu -g
   

5. Remove Node via Snap.

   sudo snap remove node
   

6. Install Node via apt.

   sudo apt install nodejs
   

[pachulo]

We were bitten by this same problem, and we think that is related to this: https://forum.snapcraft.io/t/snapd-2-32-breaks-live-server-installer/4597

[kleinfreund]

I’m closing this because there hasn’t been a response or interest in this issue (which is still happening).

[kleinfreund]

For posterity, both the following scripts produce the empty string when their commands executed in a shell return a completely different (and expected) results:

const npm = require('child_process').spawnSync('npm', ['ls', '--global', '--depth=0', '--json', '--prefix=/home/phil/.npm-global'])
console.log(String(npm.stdout) === '');

The asynchronous variant never runs into either callbacks for stdout or stderr and completes with child process exited with code 0.

const npm = require('child_process').spawn('npm', ['ls', '--global', '--depth=0', '--json', '--prefix=/home/phil/.npm-global'])

npm.stdout.on('data', (data) => {
    console.log(`stdout: ${data}`);
});

npm.stderr.on('data', (data) => {
    console.error(`stderr: ${data}`);
});

npm.on('close', (code) => {
    console.log(`child process exited with code ${code}`);
});

[kleinfreund]

This is still broken in the Snap distribution of Node.js.

The following short program logs true even though the expression String(npm.stdout) should evaluate to a dependency graph of globally installed npm packages.

const npm = require('child_process').spawnSync('npm', ['ls', '--global', '--depth=0', '--json', '--prefix=/home/phil/.npm-global'])
console.log(String(npm.stdout) === '');

This issue makes the Snap distribution of Node.js unuseable for me.

[desmap]

I just had the same issue with coc.vim which relies on node. When it`s installed via snap coc.vim cannot check node's version number: neoclide/coc.nvim#2870

[igsu]

We are not responsible for maintaining the Snap packages, to solve any issue or more information:

https://github.com/nodejs/snap