Set NODE_ENV from Grunt task

Question

I would like to set the NODE_ENV variable at the beginning of a Grunt task, to development or production, but it looks it's not as simple as I thought.

The reason, why I would like this is that I use grunt-webpack, which expects NODE_ENV to be set correctly to "development" or "production". But I also would like to initialize my tasks exclusively from grunt, if possible.

I created the following test Gruntfile, using the grunt-shell and cross-env modules:

function log(err, stdout, stderr, cb, e) {
    if (err) {
        cb(err);
        return;
    }

    console.log(process.env.NODE_ENV);
    console.log(stdout);
    cb();
}

module.exports = function(grunt) {

    grunt.initConfig({
        shell: {
            dev: {
                command : 'cross-env NODE_ENV="development"',
                options: {
                    callback: log
                }
            },
            dist: {
                command : 'cross-env NODE_ENV="production"',
                options: {
                    callback: log
                }
            }
        }
    });

    grunt.loadNpmTasks('grunt-shell');

};

Line 6 of log() should echo the actual value of process.env.NODE_ENV, but it constantly says undefined, even if I check it manually in the node console.

If I set it manually from the terminal, like set NODE_ENV=production (set is for Windows), everywhere echoes the value production, as I would like it to.

`cross-env` I'm just using because of the local windows environment, `command : 'NODE_ENV="production"',` also fails when trying on the server. — bencergazda, Jul 07 '17 at 11:01
clarification your question doesn't mention it but your bounty does -- you are using grunt-webpack correct? and have you looked at [grunt-env](https://www.npmjs.com/package/grunt-env) by chance? — aug, Jul 19 '17 at 10:56
@aug Thanks for your comment. Yes, I am using grunt-webpack, updated the question. I tried with [grunt-env](https://github.com/jsoverson/grunt-env) as well, but that also didn't work. I've even found an issue with the same problem: [Not working · Issue #43 · jsoverson/grunt-env](https://github.com/jsoverson/grunt-env/issues/43) — bencergazda, Jul 19 '17 at 13:32

score 1 · Accepted Answer · answered Jul 21 '17 at 15:55

Your test won't work because grunt-shell runs a child_process and your callback runs after it ends and under the main process.
Same thing would happen with cross-env.

If you want to pass an environment variable to grunt-shell, you should use the options configuration according to the documentation.
For example:

grunt.initConfig({
    shell: {
        dev: {
            command : 'echo %NODE_ENV%', //windows syntax
            options: {
                execOptions: {
                    env: {
                        'NODE_ENV': 'dev'
                    }
                },
                callback: log
            }
        }
    }
});

This will still print undefined for process.env.NODE_ENV, but the value of NODE_ENV will be available in the stdout because of the echo.

On a side note, it sounds like you're trying to run a process (grunt-shell), which runs a process (cross-env), which runs a process (webpack or grunt-webpack).
Why not just use the cross-env example usage? It looks pretty close to what you need.
Or you can just define the variable in the task config itself and lose all of these wrappers.

Thank you for your detailed response. I accept it as an answer, as it already made a lot of things clearer to me. But regarding to your answer, it looks to me that it is not possible to do what I want, is it? I mean, I see that I can add a script to package.json's scripts field, which sets the `NODE_ENV` to what I want and starts a grunt-task, but it's impossible to set the `NODE_ENV` *in a grunt task* and use it immediately in another grunt task, because `process.env.NODE_ENV` will be still `undefined`. Am I right? — bencergazda, Jul 25 '17 at 13:29
@bencergazda it depends. If you set `process.env.NODE_ENV` inside the grunt task it will work for as long as grunt doesn't create another `child_process` to run an additional task. In your example you use `grunt-shell` which does this and that's why it didn't work. But if you use `grunt-webpack` directly, it should work for you. — LifeQuery, Jul 25 '17 at 14:00

score 0 · Answer 2 · answered Jul 26 '17 at 10:38

LifeQuery's answer helped me a lot to find out what the problem actually was. I first realized that webpack.DefinePlugin() actually doesn't change anything on process.env.NODE_ENV (and it would be too late anyway, as it transforms code parsed by webpack after all loaders).

After this I created a solution, which does what I want. This is how my customized Gruntfile.js begins:

'use strict';

const path = require('path');
const webpack = require('webpack');

module.exports = function (grunt) {

    // Setting the node environment based on the tasks's name or target
    let set_NODE_ENV = function () {
        const devTasks = ['webpack-dev-server', 'dev', 'hmr', 'watch'],
            devTargets = [':dev'],
            task = grunt.cli.tasks[0], // The name of the (first) task we initialized grunt with ('webpack-dev-server' if started 'grunt webpack-dev-server)
            target = ':'+grunt.option('target'),
            devEnv = (devTasks.indexOf(task) > -1 || devTargets.indexOf(target) > -1);

        process.env.NODE_ENV = devEnv ? 'development' : 'production';
    }();

    const webpackConfig = require('../assets/webpack.config');

    grunt.initConfig({
        // ...usual Gruntfile content
    });

};

I created a whitelist of grunt task names and targets when I set the process.env.NODE_ENV. As it is placed before the grunt.initConfig(), the configuration object can use process.env.NODE_ENV with the desired state.

It will set NODE_ENV to "development" if starting definitely webpack-dev-server, dev, hmr or watch tasks, or any other tasks with the :dev target.

Set NODE_ENV from Grunt task

2 Answers2