My application heavily relies on AWS services, and I am looking for an optimal solution based on them. Web Application triggers a scheduled job (assume repeated infinitely) which requires certain amount of resources to be performed. Single run of the task normally will take maximum 1 min.
Current idea is to pass jobs via SQS and spawn workers on EC2 instances depending on the queue size. (this part is more or less clear) But I struggle to find a proper solution for actually triggering the jobs at certain intervals. Assume we are dealing with 10000 jobs. So for a scheduler to run 10k cronjobs (the job itself is quite simple, just passing job description via SQS) at the same time seems like a crazy idea. So the actual question would be, how to autoscale the scheduler itself (given the scenarios when scheduler is restarted, new instance is created etc. )? Or the scheduler is redundant as an app and it is wiser to rely on AWS Lambda functions (or other services providing scheduling)? The problem with using Lambda functions is the certain limitation and the memory provided 128mb provided by single function is actually too much (20mb seems like more than enough)
Alternatively, the worker itself can wait for a certain amount of time and notify the scheduler that it should trigger the job one more time. Let's say if the frequency is 1 hour:
1. Scheduler sends job to worker 1
2. Worker 1 performs the job and after one hour sends it back to Scheduler
3. Scheduler sends the job again
The issue here however is the possibility of that worker will be get scaled in.
Bottom Line I am trying to achieve a lightweight scheduler which would not require autoscaling and serve as a hub with sole purpose of transmitting job descriptions. And certainly should not get throttled on service restart.