Cron-cluster


Cron cluster is designed to prevent a job which must be launched only once to be launched many times while
an app is scaling accross a cluster with the same task scripts.

Cron cluster is based on node-cron and redis-leader to prevent a cron job to be launched if
his process has not been elected as leader on redis.

Requirement

Redis

Install

``bash
npm install cron-cluster
`

Usage

Cron cluster use the same API as the original CronJob.

`js
var redis = require('redis').createClient()
var CronJob = require('cron-cluster')(redis).CronJob

function doCron () {
var job = new CronJob(' ', function () {
// Do some stuff here
})
job.start()
}
`

It is possible to initialize CronJob with an object passed as parameter and run the job only once for all the instances.
Cron-cluster is compatible with original cron. More in test/cron-cluster-compatibility-check.js

`js
var redis = require('redis').createClient()
var CronJob = require('cron-cluster')(redis).CronJob

function doCron () {
var job = new CronJob({
cronTime: ' ',
onTick: function () {
// Do some stuff here
}
})
job.start()
}
`

All you need is to provide a redis client to the cron-cluster module.

Example

Usage with Kue:

`js
var kue = require('kue'),
queue = kue.createQueue()
var redis = require('redis').createClient()
var CronJob = require('cron-cluster')(redis).CronJob

new CronJob(' ', function () {
queue.create('log', {
text: 'this is a log'
}).save()
}, null, true)

queue.process('log', function (job, done) {
console.log(job.data.text)
done()
})
``