smi

Package Installation. Evolved.

Status: DEV

The smi command installs packages and assets mapped in a package.json file into the directory structure of the declaring package.

It addresses the package installation features needed by a modern development workflow and can be thought of as building on top of npm.

Most notably; smi adds an abstraction layer allowing the mapping of arbitrary external resources into arbitrary aliased namespeces within the package. This divorces the dependency implementation from the use of the dependency which is the foundation for supporting recomposable applications and systems.

At any time you should be able to overlay the package descriptor (package.json) and set a different dependency implementation for a given environment the package will run in. Assuming the alternate implementation exposes the same API, the declaring package should function as before.

smi embodies these principles and thus is a package installer suitable for use in a distributed system with diverse deployment requirements.

Features:

• Declare dependencies using JSON
• Install dependencies using command-line call
• Idempotent operation for easy scripting integration
• Compatible with npm ecosystem
• Takes npm dependencies to another level
• Reference assets using URIs
• Reference assets using catalogs
• Embeddable into NodeJS apps
• Circular dependencies are no problem
• Compose arbitrary namespaces
• Environment specific dependencies
• Extract many different types of archives

Install

npm install -g smi.cli

Usage:

smi -h

Test:

npm test

Docs

Declaring dependencies

package.json

{
	"upstream": {
        "packages": {
        	// Auto-link dependencies
            "./local": "./../common/*"
        },
		"catalogs": {
			"<id>": "<locator>",
			"archiveA": "./catalog.json"
		}
	},
	"mappings": {
		"<id>": "<locator>",
		// Place extracted archive anywhere
		"./local/archive1": "http://remote.com/archiveA.tar.gz",
		// or into `_packages` by default
		"archive1": "http://remote.com/archiveA.tar.gz",
		// Map packages using a catalog
		"archive2": "catalog1/archiveA"
	}
}

catalog.json

{
	"packages": {
		"archiveA": "http://remote.com/archiveA.tar.gz"
	}
}

For a complete resource of supported locators see ./test/assets.

Installing Dependencies

By calling smi directly from the command-line:

smi install

A typical approach is to integrate it into the installation procedure of an existing npm package which can be done as follows.

package.json

{
	"dependencies": {
		"smi.cli": "0.x"
	},
	"scripts": {
		"install": "./node_modules/.bin/smi install"
	}
}

Extending Descriptors

To compose the dependencies of a package one can extend existing descriptors. Each successive descriptor gets merged on top of the previous one after resolving its own extends URLs and finally the declaring descriptor (and its overlays) have final say.

{
	"extends": [
		"./local/prototype/descriptor.json",
		"http://remote.com/prototype/descriptor.json",
		"<id>/prototype/descriptor.json"
	]
}

TODO

• Wrap various third party installers (e.g. bower, composer)
• Resolve version selectors into release streams
• Write install history
• Write more meta data
• Cleanup
• Refactor to run on pinf program prototype

License

Copyright (c) 2014 Christoph Dorn

MIT License