Installing npm modules globally without sudo

I needed to install pm2 globally and run it as non root. This meant installing it with npm without using the sudo command. However, when you do this npm will throw an error.

“Error: EACCES: permission denied”

The npm documentation does provide a solution that works, which has a caveat.

  1. Make a directory for global installations:
    mkdir ~/.npm-global
  2. Configure npm to use the new directory path:
    npm config set prefix '~/.npm-global'
  3. Open or create a ~/.profile file and add this line:
    export PATH=~/.npm-global/bin:$PATH
  4. Back on the command line, update your system variables:
    source ~/.profile

As a side note, an easier way to execute step 3 is:

echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.profile

When I initially executed these steps it worked. However, after logging out and in again the pm2 command was no longer available. It turns out that on login the .bash_profile file is loaded instead of the .profile. Actually bash will try loading ~/.bash_profile, ~/.bash_login and ~/.profile, in that order. Once it finds one of them it will not try and load any of the others. After adding the statement to .bash_profile it worked like a dream.

echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.bash_profile

Hope this helps someone.

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Override module loaded by require

I was using the module redact-secrets with Winston logger. This module makes sensitive data like passwords unreadable in logfiles. Very cool and handy module. It makes use of another module is-secret that contains a collection of patterns to determine what sensitive data is. One piece of sentive data was missing from is-secret: pass. I could fix it on my side, but I prefer the original GitHub project to be updated so others can also profit from it. So I submitted an issue on GitHub. While waiting for the fix I needed to continue with my development work. So I used another handy module override-require. This module overrides the resolution logic of require. So you can use it to override a dependency of a module. I used it in the following to overrule is-secret used by redact-secrets.

const overrideRequire = require('override-require');

// Check if a request needs to be overridden
const isOverride = (request) => {
return request === 'is-secret';
};

// If isOverride is true, load the module with the overridden module
const resolveRequest = (request) => {
return require('./overrule/is-secret');
};

// Initialize overide-require
const restoreOriginalModuleLoader = overrideRequire(isOverride, resolveRequest);

const { createLogger, format, transports } = require('winston');
// When redacts-secrets is loaded override-require will kickin and load our own module
const redact = require('redact-secrets')('******');
const fs = require('fs');
const path = require('path');

// Disable override require
restoreOriginalModuleLoader();

 

That’s it. Pretty cool isn’t it?

Testing Mongoose plugin with Jest and shared data

Grrrr just spent the better half of 2 hours trying to figure out why my Jest tests were not working for a Mongoose plugin I’m developing. It turns out that the schema configuration I was sharing between the tests was the culprit.

let Mongoose = require('mongoose');
let Schema = Mongoose.Schema;
const _ = require('lodash');
var mongooseI18n = require('../src/mongoose/mongoose-i18n-localize');

Mongoose.set('debug', true);

const simpleSchemaConfig = {
  firstName: { type: String, i18n: true, required: true },
  lastName: { type: String, i18n: false, required: true }
};

describe('Mongoose i18n localize', () => {
  beforeEach(() => {
    // Clear compiled models to avoid OverwriteModelError
    Mongoose.models = {};
  });
  
  it('should throw an exception if the locales array is not defined', () => {
    const SimpleTestSchema = new Schema(simpleSchemaConfig);
    expect(() => {
      SimpleTestSchema.plugin(mongooseI18n, {
        defaultLocale: 'nl',
        allLocalesRequired: false
      });
    }).toThrow('The required option locales array not provided or empty');
  });

  it('should throw an exception if the locales array is an empty array', () => {
    const SimpleTestSchema = new Schema(simpleSchemaConfig);
    expect(() => {
      SimpleTestSchema.plugin(mongooseI18n, {
        locales: [],
        defaultLocale: 'nl',
        allLocalesRequired: false
      });
    }).toThrow('The required option locales array not provided or empty');
  });

  ...

});

The plugin makes changes to the schema configuration and these changes were made to the shared config. The fix I used was to make a copy of the shared config with lodash’s cloneDeep function. The only change I needed to make was the schema initialization.

const SimpleTestSchema = new Schema(_.cloneDeep(simpleSchemaConfig));

Now my tests run like a charm 🙂

Bonus

When I initially ran into the above problem, I was also initializing the schema globally. I thought that was the problem, so I moved the following statement to each test case.

const SimpleTestSchema = new Schema(simpleSchemaConfig);

That caused the exception OverwriteModelError, because I was trying to initialize a compiled model. The fix for this problem was to remove all models between test cases using beforeEach. The following code does the trick.

beforeEach(() => {
  // Clear compiled models to avoid OverwriteModelError
  Mongoose.models = {};
});

Hope this helps someone.