npm ignores process signals when bundled with node >=20.3.0

[ryanrasti]

Version

v20.5.0

Platform

Linux nixos 5.15.93 #1-NixOS SMP Thu Feb 9 10:26:48 UTC 2023 x86_64 GNU/Linux

Subsystem

npm

What steps will reproduce the bug?

The below script sends a SIGTERM to the npm process that spawned it. Run npm run test with:

In package.json

    {
      "name": "test",
      "version": "0.0.0",
      "type": "module",
      "scripts": {
        "test": "node test.js"
      }
    }

In test.js

    import { execSync } from 'child_process';

    process.on('SIGTERM', () => {
        console.log('Received SIGTERM. Exiting...');
        process.exit(0);
    });

    const output = execSync('ps -e | grep npm').toString().split(/\s+/).filter(Boolean);
    const pid = Number(output[0]);
    process.kill(pid)

    setTimeout(() => {
        console.log('Fatal: Signal was not received. Exiting... ');
        process.exit(1)
    }, 2000);

How often does it reproduce? Is there a required condition?

release >= 20.3.0: Always reproduces.
release <= 20.2.0: Can't reproduce.

What is the expected behavior? Why is that the expected behavior?

Expected that the above program exits with code 0 (i.e., npm is aborted by the signal and the script handles the signal as well)

What do you see instead?

Program exits with code 1 (npm doesn't appear to receive the signal). npm itself also doesn't abort.

Additional information

All-in-one command to reproduce. Run nix-build repro.nix where repro.nix has content:

{ pkgs ? import
    (builtins.fetchTarball
      {
        name = "nixpkgs-23.11pre506668.af8cd5ded77";
        url = "https://releases.nixos.org/nixpkgs/nixpkgs-23.11pre506668.af8cd5ded77/nixexprs.tar.xz";
        sha256 = "sha256:0in8bgah6hz47lsa3ka2fslwks174maqdzy8mcmsj0q4wrv8h2s9";
      })
    { }
}:
let
  package = pkgs.writeText "package.json" ''
    {
      "name": "test",
      "version": "0.0.0",
      "type": "module",
      "scripts": {
        "test": "node test.js"
      }
    }
  '';
  script = pkgs.writeText "test.js" ''
    import { execSync } from 'child_process';

    process.on('SIGTERM', () => {
        console.log('Received SIGTERM. Exiting...');
        process.exit(0);
    });

    const output = execSync('ps -e | grep npm').toString().split(/\s+/).filter(Boolean);
    const pid = Number(output[0]);
    process.kill(pid)

    setTimeout(() => {
        console.log('Fatal: Signal was not received. Exiting... ');
        process.exit(1)
    }, 1000);

  '';
in
pkgs.runCommand "test"
{
  buildInputs = [ pkgs.nodejs_20 pkgs.ps ];
} ''
  node --version
  cp ${package} package.json
  cp ${script} test.js
  npm run test | tee $out
''

To get the working version (node v20.2.0), replace the import statement above with:

import
    (builtins.fetchTarball
      {
        name = "nixpkgs-23.05pre476152.2362848adf8";
        url = "https://releases.nixos.org/nixpkgs/nixpkgs-23.11pre491680.31cd1b4afba/nixexprs.tar.xz";
        sha256 = "sha256:109h43svy4gzl9bnwsgdwiyghv23bf2bwya396khqscjqakd14md";
      })
    { }

This is the breaking nix commit.

[bnoordhuis]

v20.3.0 contains an upgrade from npm 9.6.7 to 9.8.1 so chances are good it's a change in behavior in npm, not node. Further evidence: sending signals directly to the node process works as expected.

Can you report this to upstream npm? It's not actionable for us.

[aduh95]

I'm going to close this as it appears to be a npm bug, not a node one, let me know if I'm missing something and should re-open this.

[richardlau]

Adding links.

• npm issue: [BUG] npm not handling process signals npm/cli#6684
• possibly fixed by Revert Signal Handling Regression npm/run-script#188 which was included in @npmcli/[email protected] which was included in npm 10.3.0. This version of npm hasn't gone out in a current (i.e. Node.js 21) release yet -- usually we'd want two weeks in a current release before backporting/cherry-picking to LTS release lines (i.e. Node.js 20 and 18).