Use local-npm for offline NPM package installation

npm is a Node.js package manager. Users can fetch and install Node.js packages easily using npm. It makes it easier to resolve package dependencies.

The official repository of npm is https://www.npmjs.com/

 

Why do we need offline NPM package installation?

There are scenarios where not every user has access to the official npm repository. For example:

• You may deliver an on-site workshop. The trainees need to run npm install for their lab in the restricted environment.
• You may need to install packages on a flight.

 

Why do I choose local-npm?

Addy Osmani has a nice post comparing local-npm to other options. I just follow this post.

 

local-npm Installation

Environment: I am using a Windows 2008 R2 Server with .NET Framework 4.5.2 installed.

 

1. Install Node.js

Download and install the current version of Node.js from https://nodejs.org/en/download/

Because local-npm depends on node-gyp, you need to install Python 2.7 (v3.x.x is not supported) and Visual C++ Build Environment. (Refer to the document of node-gyp) Otherwise you will receive the following error when you run the command npm install -g local-npm directly.

2. Install Visual C++ Build Environment

• Option 1: Install Visual C++ Build Tools using the Default Install option.
• Option 2: Install Visual Studio 2015 (or modify an existing installation) and select Common Tools for Visual C++ during setup.

3. Install Python 2.7

Download and install Python 2.7 from https://www.python.org/downloads/ (I installed it in the default folder c:\python27)

You may meet the following error during Python 2.7 installation:

"There is a problem with this Windows Installer Package. A program required for this install to complete could not be run. Contact your support personnel or package vendor"

I applied the solution in this Stack Overflow post.

• De-select pip from the install options. Then install.
• After the installation completes, re-run the setup.
• Choose "change python" and then install pip.

4. Launch command prompt, run the command npm config set python C:\Python27\python.exe

5. Run the command npm config set msvs_version 2015

6. Simply run the command npm install -g local-npm

Basic Usage of local-npm

Before you run the command local-npm to start local-npm, you'd better create a folder (e.g. c:\local-npm) and change the current directory to this folder. The reason to create a specific folder is because local-npm will replicate the skimdb from the official repository and store the data in local folder. The default folder to store the data is the folder where you run local-npm. (You can specific the folder by the command line option -d, --directory)

Run the command local-npm

Then the users can set npm to get registry through the local server:

npm set registry https://127.0.0.1:5080

If you want to switch back to the official repository, run this:

npm set registry https://registry.npmjs.org

Now the users can run npm install to get the package through the local-npm server.

Offline mode

After you start local-npm, it will begin to replicate skimdb from remote official registry.

There's no need to wait for the complete skimdb download (which can take a few hours). You can test it with the following steps:

1. Make sure the network is up.
2. Run an npm install to grab a module. (e.g. npm install jquery)
3. local-npm will cache it.
4. delete jquery from node_modules directory.
5. Turn off the network.
6. Run that npm install again. (e.g. npm install jquery)
7. You will notice the following behaviors
   • If the complete skimdb has been replicated (100%), you will get the cached package immediately from local-npm.
   • If the replication is still in process, local-npm will try to connect to the official registry three times. After about 1 minutes, you will still get the cached package from local-npm.