vs-service

Tool for keeping track of service components in a cluster

Installation

npm install vs-service

Quick Start

var service = require('vs-service');

var url = 'mongodb://localhost/sandbox';

var name = 'Test';
var port = 8080;

var stun = { host: 'stun.l.google.com', port: 19302 }

var appsrvc = service.create(name, port, stun, url);
var cluster = service.cluster(url).refresh(100).cleanup(100);

appsrvc.heartbeat(100).snapshot(60000);

Service

Create a service instance representing current application process

var service = require('vs-service');

var url = 'mongodb://localhost/sandbox';

var name = 'Test';
var port = 8080;

var stun = { host: 'stun.l.google.com', port: 19302 }

var appsrvc = service.create(name, port, stun, url);

(It is important to point out that the database is expected to have services and snapshots collections already setup)

Discover

Update service document with the information about the system (os, platform, architecture, host, memory)

appsrvc.discover();

Start discovery updates

appsrvc.discover(60000);

Stop discovery updates

appsrvc.discover(false);

Heartbeat

Update service document with a new heartbeat timestamp

appsrvc.heartbeat();

Start heartbeat updates

appsrvc.heartbeat(100);

Stop heartbeat updates

appsrvc.heartbeat(false);

Snapshot

Update service document with the information about the state of the system (cpu, memory, uptime), and add the document to the snapshot history collection

appsrvc.snapshot();

Start snapshot updates

appsrvc.snapshot(60000);

Stop snapshot updates

appsrvc.snapshot(false);

Cluster

Create a cluster instance used to access information about related services

var service = require('vs-service');

var url = 'mongodb://localhost/sandbox';

var cluster = service.cluster(url);

Refresh

Setup minimum refresh interval to reduce the load on the database

cluster.refresh(100);

Cleanup

Setup the period of time after which stale services with no heartbeat are eliminated

cluster.cleanup((500);

Retrieve

Get all services from the database services collection

cluster.retrieve(function ( error, value ) {
  if ( !error ) {
    for ( var name in value ) {
      console.log(name + ' service instances: ' + value[name].length);
    }
  }
  else console.log('An error occurred: ' + error);
});

Select One

Get a single instance of a service that matches required criteria best (for now it automatically selects instance with the most amount of resources)

cluster.selectOne('Test', function ( error, value ) {
  if ( !error ) {
    if ( !value ) {
      console.log('There is no instance available');
    }
    else {
      console.log('Best test service is running on ' + value.host);
    }
  }
  else console.log('An error occurred: ' + error);
});

Select All

Get all instances of a service

cluster.selectAll('Test', function ( error, value ) {
  if ( !error ) {
    for ( var i = 0; i < value.length; i += 1 ) {
      console.log('Test service is running on ' + value[i].host);
    }
  }
  else console.log('An error occurred: ' + error);
});

License

MIT