Go NPM

Distribute cross-platform Go binaries via NPM

Applications written in Golang are portable - you can easily cross-compile binaries that work on Windows, Mac, and Linux. But how do you distribute the binaries to customers? When you publish new releases, how do they update the binary?

Use NPM to distribute cross-platform Go binaries

Kidding me! Why NPM?

• Cross-platform: NPM is the only popular package manager that works cross-platform.
• Lower barier to entry: Most developers have NPM installed already.
• Pain free publishing: It just takes one command to publish - npm publish
• Dead simple install & update story: npm install/update -g your-awesome-app
• Adds $PATH: NPM will automatically add your binary location to $PATH and generate .cmd file for Windows. Your app just works after installation!

Okay, tell me how?

1. Publish your binaries

Setup your Go application to compile and publish binaries to a file server. This could be Github Releases or Amazon S3 or even Dropbox. All you need is a link.

I like to use GoReleaser to setup by release process. You create a simple YAML configuration file like this and run goreleaser CLI to publish binaries for various platform/architecture combination to Github:

# .goreleaser.yml
# Build customization
builds:
  - binary: drum-roll
    goos:
      - windows
      - darwin
      - linux
    goarch:
      - amd64

go-npm will pull the appropriate binary for the platform & architecture where the package is being installed.

2. Create a package.json file for your NPM app

To publish to NPM, you need to create a package.json file. You give your application a name, link to Readme, Github repository etc, and more importantly add go-npm as a dependency. You can create this file in an empty directory in your project or in a separate Git repository altogether. It is your choice.

Create package.json

$ npm init

Answer the questions to create an initial package.json file

Add go-npm dependency

From the directory containing package.json file, do

$ npm install go-npm --save

This will install go-npm under to your package.json file. It will also create a node_modules directory where the go-npm package is downloaded. You don't need this directory since you are only going to publish the module and not consume it yourself. Let's go ahead and delete it.

$ rm -r node_modules

Add postinstall and preuninstall scripts Here is the magic: You ask to run go-npm install after it completes installing your package. This will pull down binaries from Github or Amazon S3 and install in NPM's bin directory. Binaries under bin directory are immediately available for use in your Terminal.

Edit package.json file and add the following:

{
    "postinstall": "go-npm install",
    "preuninstall": "go-npm uninstall",
}

go-npm uninstall simply deletes the binary from bin directory before NPM uninstalls your package.

Configure your binary path

You need to tell go-npm where to download the binaries from, and where to install them. Edit package.json file and add the following configuration.

 "goBinary": {
    "name": "myBinaryName",
    "path": "./bin",
    "archives": {
      "windows": {
        "x64": "https://github.com/pgollangi/fastget/releases/download/{version}/fastget_{version}_windows_x86_64.zip",
        "x32": "https://github.com/pgollangi/fastget/releases/download/{version}/fastget_{version}_windows_i386.zip"
      }
    }
  }

• name: Name of the command users will use to run your binary.
• path: Temporary path where binaries will be downloaded to
• archives: List of archive URLs for each OS and ARCHs

Following variables are available to customize the URL:

• {{version}}: Version number read from package.json file. When you publish your package to NPM, it will use this version number. Ex: 0.0.1

If you use goreleaser to publish your modules, it will automatically set the right architecture & platform in your URL.

Publish to NPM

All that's left now is publish to NPM. As I promised before, just one command

$ npm publish

3. Distribute to users

To install:

npm install -g your-app-name

To Update:

npm update -g your-app-name