wahengchang/nodejs-cron-job-must-know

it is an example of running node.js script with every certain period(cron job)

nodejs-cron-job-must-know

it is an example of running Node.js script with every certain period(cron and non-cron job)

Why don't we use Linux crontab

• We can provide the full path to node /usr/local/bin/node in your cron job like:
  • 30 6 1 * * /usr/local/bin/node /home/steve/example/script.js
• Or making a script with the command, and then adding that to cron:

  #!/usr/bin/env sh 
  node /home/campaigns/reporting/UNIT_TESTS/testCron.js > /home/campaigns/reporting/UNIT_TESTS/cron.log
  

• The problem with the two above methods is messing up the path. The command is in absolute path, but the Node.js script uses relative path to import/require other modules. It causes the error of file not found. So we need to execute the cron under the directory of Node.js script, which contains all the modules which will be used.

Install

This lib is used to keep the cron-job alive, which triggers the node script at a certain time.

$ npm install --save node-cron

Usage

Import node-cron and schedule a task:

Read more

var cron = require('node-cron');
 
cron.schedule('* * * * *', function(){
  console.log('running a task every minute');
});

Run Node.js script in cron

• To run script : $ node script1.js
• And script: $ npm run script -- PeterGood
• child_help.js is an amazing Node.js script from mout, which helps to manage multiple linux commands.

Start a Daemon, and run

$ node cronNodeScript

Execute script every 1 min

//execute every 1 min
cron.schedule('*/1 * * * *', function(){
    ....
});

Execute $ node script1.js and npm run script -- PeterGood every 1 min

//execute every 1 min
cron.schedule('*/1 * * * *', function(){
    var shell = require('./child_helper');

    var commandList = [
        "node script1.js",
        "npm run script -- PeterGood"
    ]

    shell.series(commandList , function(err){
    //    console.log('executed many commands in a row'); 
        console.log('done')
    });
});

Reference:

• https://www.npmjs.com/package/node-schedule
• https://www.npmjs.com/package/node-cron
• https://stackoverflow.com/questions/7194102/node-js-script-not-executing-from-crontab
• https://stackoverflow.com/questions/5849402/how-can-you-execute-a-node-js-script-via-a-cron-job

nodejs-cron-job-must-know's Issues

Misspelling

//exceute every 2:30am morning
// cron.schedule('30 2 * * *', function(){
// console.log('running a task every two minutes');
// });

//exceute every 1 min

exceute --> execute

Need help in skipping cronjob when already scripts for previous cronjob are running

I have written a cron job as given below

var cron = require('node-cron');
var taskMap = {};
let job = cron.schedule('*/1 * * * * ', ()=>{
var shell = require('./utils/child_helper');

var commandList = [
"node *****",
"node *****",
"node ******"
]

shell.series(commandList , function(err,res){
// console.log('executed many commands in a row');
console.log('done')
});
});

which need to run on every 1 min but the scripts inside the cron may take more than 1 min.
I need to skip the cron for the moment when the scripts are still running .
Can anyone help me on it.

Calling cron from app.js as below code

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
var port = 3000;
require('./cronController').job.start();

app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.listen(port , ()=>{
let dateTime = new Date();
let message = 'Server is running on Port :- ' + port + ' started at :- ' + dateTime;
console.log(message);
});