Using spawn function with NODE_ENV=production

This worked for me

var spawn = require('child_process').spawn;
var productionEnv = Object.create(process.env);
productionEnv.NODE_ENV = 'production';
var start = spawn('node', ['app.js'], {env: productionEnv});

this did not

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

Syntax: spawn(command, [args], [options])

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

Or keep default ENV variables:

var spawn = require('child_process').spawn;

var productionEnv = process.env; // TODO should clone process.env like utils.extend
productionEnv.NODE_ENV = 'production';

var start = spawn('node', ['app.js'], {env: productionEnv});

---

My test:

app.js

console.log(process.env);

spawn.js

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

start.stdout.pipe(process.stdout);

from terminal:

node spawn

output:

{ NODE_ENV: 'production' }

Your usage of spawn is not correct:

spawn( command, args, options ):

Launches a new process with the given command, with command line arguments in args. If omitted, args defaults to an empty Array.

The third argument is used to specify additional options, which defaults to:

{ cwd: undefined, env: process.env }

Use env to specify environment variables that will be visible to the new process, the default is process.env.

So the env variable NODE_ENV should be provided on the options argument:

// ES6 Object spread eases extending process.env
spawn( 'node', ['app.js'], { env: { ...process.env, NODE_ENV: 'test' } }})

See also How do I debug "Error: spawn ENOENT" on node.js?