init-system

Declarative startup/shutdown for your Node.js apps.

This solution has a dependency declarations similar to Linux startup systems or Makefiles. It also has inversion of control similar to middleware.

Project status

Unmaintained

This module saw sucessful deployments into production for projects I worked on, but we eventually decided to move to booture. The functionality and syntax are similar, but it offers cleaner integration into Fluture and well defined behaviour since it's based on Fluture Hooks.

Usage

First we need to declare our services.

// services/my-service.js

module.exports = {

	// The name of this service.
	provides: 'myService',

	// The dependencies of this service.
	after: ['config', 'database'],

	/*
		Below is the startup and shutdown logic.

		services: object
			This object holds all of the dependencies
			declared in "after".

		provide: function(value) => Future
			A function you need to call to signal
			your service is created and ready for use.
	*/
	service: function*(services, provide) {

		// Use your dependencies.
		const myService = new MyService(services.config, services.database);

		// Let init-system know the service is ready.
		const exitCode = yield provide(myService);

		// Do our shutdown logic.
		myService.close();

		// Pass on the exit code.
		return exitCode;
	}

};

Then in our main script, load them using init-system.

// index.js

const init = require('init-system');

init.services(

	// Ordering is done in the service descriptions,
	// so we can simply provide an unsorted array.
	[
		require('./services/config.js'),
		require('./services/my-service.js'),
		require('./services/database.js')
	],

	// Node callback.
	function(err, exitCode){
		if(err){
			console.error(`Error during application startup / shutdown: ${err}`);
		} else {
			console.log(`Application exitted with ${exitCode}`);
		}
	}

);

Available options

You can call init.services(services, [options], callback) with an options object to change some behavior.

key	type	description
logger	function(message)	Allows you to set a logger for verbose startup / shutdown messages.

View example usage for the options

const options = {

	// Sets a logger for verbose startup / shutdown messages.
	logger: function(message) {
		console.log('init-system', message);
	}

};

init.services(
	[/* services */],
	options,
	function(err, exitCode) { /* callback */ }
);