Loopback 4: Scheduled cron example using Loopback 4 - loopbackjs

Question

As I am very new with loopback 4 and Typescript, knowing that we have to use custom booter to implement schedule tasks like Cron.
I require a code snippet which does that, i.e A custom booter class that implements Booter phases of configure, discover and load to Run a Cron

Answer 1

I am not sure this is the way to do it, but this is working for me.
https://loopback.io/doc/en/lb4/Booting-an-Application.html#bootcomponent
Start with creating a component inside the project folder. I created src\components\cron.component.ts
import { Component } from "#loopback/core";
import { CronJob, CronCommand } from "cron"
export class CronJobsComponent implements Component {
private cj: CronJob;
constructor(){
this.start()
}
async start(){
this.cj = new CronJob('* * * * * *', this.showMessage)
this.cj.start();
}
showMessage:CronCommand = async () => {
console.log("inside cron jobs")
}
}
Next import our component in the application.ts file
import { CronJobsComponent } from './components'
and register our new component inside the constructor
this.component(CronJobsComponent);
The corn job starts on application boot.
I used https://www.npmjs.com/package/cron and https://www.npmjs.com/package/#types/cron
Hope this helps you.

Answer 2

You can always create a cron endpoint.
http://localhost:3000/cron
You could then add a curl command to your crontab.
curl http://localhost:3000/cron
This method is a great way to handle seperation of concerns. If your api is a microservice running on kubernetes, you could call the cron endpoint using the Cron resource.
Just make sure that the endpoint is secure if your application is public.