AWS and NodeJS architecture for a scheduled/cron task in multi server setup

Question

I am using AWS services in deploying my application which currently has the production site setup on an application load balancer running 2 instances of my NodeJS server.

My current concern is if I just setup a node-cron to trigger a task at 5:00am, it will do this for each server I spin up.

I need to implement an email delivery system where at 5:00am it will query my database table I made to generate customized emails (need to iterate over each individual;s record which has a unique array that helps build a list of items for each user). I then fire the object off to AWS SES.

What's are some ways you have done this?

• **Currently based off my readings I am looking at two options:
• **

Setup a node-cron child process within one cluster (but if I have auto-scaling, wouldn't this create a duplicate node-cron task), but this would probably require Redis and tracking the process across servers

OR

Setup an EventBridge API which fires an api.mybackendserver.com/send-email-event where I then carry out my logic. (this seems like the simpler approach, and the drawbacks would be potential CPU/RAM spikes which would be fine as i'm regionally based and would do this in off-peak hours).

Answer 1

EventBridge is definitely a way to go with CRON. If you're worried about usage spikes you could use CRON to invoke a Lambda function. That pushes events to SQS for each job. Those would be polled by EC2 instances.

Other way would be to schedule a task to increase number of instances before cron event occurs.