service-runner.js

#!/usr/bin/env node

'use strict';

/**
 * Fairly generic cluster-based web service runner. Starts several instances
 * of a worker module (in this case the restface module), and manages restart
 * and graceful shutdown. The worker module can also be started independently,
 * which is especially useful for debugging.
 */

const cluster = require( 'cluster' );
const Master = require( './lib/master' );
const Worker = require( './lib/worker' );
const Logger = require( './lib/logger' );
const makeMetrics = require( './lib/metrics' );
const P = require( 'bluebird' );

// Disable cluster RR balancing; direct socket sharing has better throughput /
// lower overhead. Also bump up somaxconn with this command:
// sudo sysctl -w net.core.somaxconn=4096
// Higher throughput, but worse load distribution can be achieved with:
// cluster.schedulingPolicy = cluster.SCHED_NONE;

// When forking, we should execute this script.
if ( cluster.isMaster ) {
	cluster.setupMaster( { exec: __filename } );
}

class ServiceRunner {
	constructor( options ) {
		if ( cluster.isMaster ) {
			this._impl = new Master( options );
		} else {
			this._impl = new Worker( options );
		}
	}

	start( conf ) {
		return this._impl.start( conf );
	}

	stop() {
		return this._impl.stop();
	}

	// @deprecated
	run( conf ) {
		return this.start( conf )
			.tap( () => {
				// Delay the log call until the logger is actually set up.
				if ( this._impl._logger ) {
					this._impl._logger.log( 'warn/service-runner',
						'ServiceRunner.run() is deprecated, and will be removed in v3.x.' );
				}
			} );
	}

	static getLogger( loggerConf ) {
		return new Logger( loggerConf );
	}

	static getMetrics( metricsConf, logger ) {
		return makeMetrics( metricsConf, logger );
	}
}

module.exports = ServiceRunner;

if ( module.parent === null ) {
	// Cancellable promises have to enabled before we instantiate any promises. Because
	// ServiceRunner heavily relies on promises this is the best place to leave the config
	// like that.
	if ( process.env.APP_ENABLE_CANCELLABLE_PROMISES ) {
		P.config( {
			cancellation: true
		} );
	}
	// Run as a script: Start up
	new ServiceRunner().start();
}