Using npm to install or update required packages just like bundler for rubygems

I love Bundler, it's great at dependency management. I love npm, installing node packages is easy! I have a nodejs app and would love to be able to specify my apps dependencies and easily install / update them wherever I deploy my app. This isn't a library I'm releasing, it's a full fledged web-app.

I'm aware of the npm bundle command, but that just seems to simply override the directory where packages are installed.

I'm used to using bundler in this fashion:

# Gemfile
gem "rails", "3.0.3"

Installs rails v3.0.3 and any other required gems on the host machine only if it doesn't already exist

> bundle install

How can I achieve something similar with npm?

As of npm 1.0 (which is now what you get by default if you follow the steps in the README file), "bundle" is no longer a segregated thing -- it's just "how it works".

So:

1. Put a package.json file in the root of your project

2. List your deps in that file

   { "name" : "my-project"
   , "version" : "1.0.0"
   , "dependencies" : { "express" : "1.0.0" } }
   

3. npm install Since you're calling this with no args, and not in global mode, it'll just install all your deps locally.

4. require("express") and be happy.

Edit: This only applies to npm versions < 1.0

It was quite difficult to figure this out, but NPM makes this possible.

You need three components

1. A subdirectory in your repository (i.e. deps/)
2. A package.json file in the above directory that lists dependencies
3. An index.js file in the above directory that requires your dependencies

Example

Imagine that express is your only dependency

deps/package.json

note: Increment the version # each time you modify the dependencies

{
  "name": "myapp_dependencies",
  "version": "0.0.1",
  "engines": {
    "node": "0.4.1"
  },
  "dependencies":{
    "express": "2.0.0beta2"
  }
}

deps/index.js

export.modules = {
  express: require('express')
  //add more
}

Now you should be able to install your dependencies using npm. You could even make this part of your deployment process

cd deps
npm install

Then within your app code you can get access to your specific version of express like this:

var express = require('myapp_dependencies').express;

You should read these two articles from Isaacs(author npm) blog. I think they are really good, and I believe tell you how to achieve your goal:

1. http://blog.izs.me/post/1675072029/10-cool-things-you-probably-didnt-realize-npm-could-do
2. http://foohack.com/2010/08/intro-to-npm/

I believe link #1(point #11) explains this:

11: Bundle all your dependencies into the package itself

When you use the npm bundle command, npm will put all your dependencies into the node_modules folder in your package. But it doesn’t stop there.

If you want to depend on something that’s not on the registry, you can do that. Just do this:

npm bundle install http://github.com/whoever/whatever/tarball/master This will install the contents of that tarball into the bundle, and then you can list it as a dependency, and it won’t try to install it when your package gets installed.

This also is handy if you have your own fork of something, and would prefer not to change the name.

In fact, you can run almost any npm command at the bundle. To see what’s inside, you can do npm bundle ls. To remove something, do npm bundle rm thing. And, of course, you can install multiple versions and activate the one you want.

As of Npm version 1.1.2 , there's a new command npm shrinkwrap which creates an npm-shrinkwrapped.json file, analogous to Gemfile.lock. It's important to make one, to prevent software rot (see Bundler's rationale). Particularly as Nodejs has such a fast moving community.

While bundle install creates a Gemfile.lock automatically, npm install won't create npm-shrinkwrapped.json (but will use it when it exists). Hence you need to remember to use npm shrinkwrap.

Read a full guide at http://blog.nodejs.org/2012/02/27/managing-node-js-dependencies-with-shrinkwrap/

It seems to me that the simplest solution is to use a package.json file with the private flag (added to npm just last month) set to true. That way, you can run npm install or npm bundle to grab your project's dependencies, but you prevent anyone from accidentally publishing your non-public project.

Here's an example package.json:

{
"name": "yourProject"
,"version": "1.0.0"
,"dependencies": { "express" : ">=2.1.0" }
,"private": true
}

Running npm install will install express on the local system if it doesn't already exist; running npm publish gives an error because of the "private": true.

You and your team can use the version tag internally to track dependency changes over time—each time you change a dependency, bump the version. To see which version you've installed, use npm ls installed.