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207 Stars 29 Forks Mozilla Public License 2.0 89 Commits 21 Opened issues


Lock down your npm dependencies by shasum.

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Put your dependencies on lockdown.


What's this?

NPM Lockdown is a tool that locks your node.js app to specific versions of dependencies... So that you can:

  1. know that the code you develop against is what you test and deploy
  2. npm install
    and get the same code, every time.
  3. not have to copy all of your dependencies into your project
  4. not have to stand up a private npm repository to solve this problem.

Who is this for?

Node.JS application developers, but not library authors. Stuff published in npm as libraries probably wouldn't be interested.

Why Care?

Even if you express verbatim versions in your package.json file, you're still vulnerable to your code breaking at any time. This can happen if a dependency of a project you depend on with a specific version itself depends on another packages with a version range.

How can other people accidentally or intentionally break your node.js app? Well, they might...

  • ... push a new version that no longer supports your preferred version of node.js.
  • ... fix a subtle bug that you actually depend on.
  • ... accidentally introduce a subtle bug.
  • ... be having a bad day.


npm install --save [email protected]

is easy to get started with. It generates a single file that lists the versions and check-sums of the software you depend on, so any time something changes out from under you,
npm install
will fail and tell you what package has changed.

One Time Project Setup

  1. npm install the version of lockdown you want:
    npm install --save lockdown
  2. add a line to your package.json file:
    "scripts": { "preinstall": "lockdown" }
  3. generate a lockdown.json:
  4. commit:
    git add package.json lockdown.json && git commit -m "be safe"

Adding new modules

  1. npm install the specific dependencies of your app
    npm install --save [email protected]
  2. re-generate your lockdown.json:
  3. commit:
    git add package.json lockdown.json && git commit -m "be safe"

Changing dependencies once locked down

You update your dependencies explicitly, relock, and commit:

npm install --save [email protected]
git add lockdown.json package.json
git commit -m "move to foo v1.2.3"


Using an npm mirror

You can fetch resources from an npm mirror by specifying the NPMCONFIGREGISTRY environment variable when invoking

npm install
. If NPMCONFIGREGISTRY is not specified, will be used.


  • You should use the latest stable version of lockdown, find it from the npm registry

Installing dependencies once locked down

npm install

Related Tools

yarn - Fast, reliable, and secure dependency management.

Fast: Yarn caches every package it downloads so it never needs to download the same package again. It also parallelizes operations to maximize resource utilization so install times are faster than ever.

Reliable: Using a detailed, concise lockfile format and a deterministic algorithm for installs, Yarn is able to guarantee that an install that worked on one system will work exactly the same way on any other system.

Secure: Yarn uses checksums to verify the integrity of every installed package before its code is executed.

npm shrinkwrap - NPM itself has a feature called "shrinkwrap" that

locks down the versions of a package's dependencies so that you can control exactly which versions of each dependency will be used when your package is installed.

At present (as of npm v1.1.33), the implementation of shrinkwrap has a couple flaws which make it unusable for certain applications:

  1. No checksums! NPM shrinkwrap does not guarantee bit-wise equality of the installed dependencies, so if an upstream server or author decides to change the contents of version 1.2.3 of
    , you'll install something different than you intended without knowing.
  2. Does not play nice with
    - If you "shrinkwrap" your app and you have an installed dep that is optional, the dependency is no longer optional. This might not be what you want.

NOTE: you can combine lockdown with shrinkwrap just fine. If all you care about is #1 above.

The path forward is to build checksums into shrinkwrap and kick lockdown to the curb, but until then, lockdown solves some problems. (@izs is interested in patches).

npm-seal - Solves the same problem as lockdown in a very different way. Because seal is built to be used in concert with shrinkwrap, it suffers from the

issue described above.

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