Can AWS scheduled scaling actions overlap?

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I found info that AWS will reject scheduled scaling actions that have overlapping recurrence strings. Taken from https://jayendrapatil.com/aws-auto-scaling/

A user is trying to setup a recurring Auto Scaling process. The user has setup one process to scale up every day at 8 am and scale down at 7 PM. The user is trying to setup another recurring process which scales up on the 1st of every month at 8 AM and scales down the same day at 7 PM. What will Auto Scaling do in this scenario

Auto Scaling will throw an error since there is a conflict in the schedule of two separate Auto Scaling Processes

However, when I tried to reproduce it, 2 overlapping policies applied and executed without any issues.

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The only issue I had if I explicitly try to define same StartTime for both recurrent scheduled scaling action. But in case I'm adding them using python/boto3/API I'm not defining StartTime explicitly and everything working fine.

The question is: Am I missing something or AWS technically allows creating overlapping scheduled scaling actions?

asked a year ago375 views
1 Answer
1
Accepted Answer

Hello,

Thanks for sharing the output and summary of the issue.

Checking this I would like to inform that when there are 2 schedules Actions that are overlapping occurrence in that case : scheduled actions within an Auto Scaling group are executed in the order that they are specified. A scheduled action generally executes within seconds. However, the action might be delayed for up to two minutes from the scheduled start time. Because scheduled actions within an Auto Scaling group are executed in the order that they are specified, actions with scheduled start times close to each other can take longer to execute.

Am I missing something or AWS technically allows creating overlapping scheduled scaling actions?

There can be Overlapping between the different schedule actions but as mentioned above : scheduled actions within an Auto Scaling group are executed in the order that they are specified. Please follow the AWS Doc for more information on Schedule actions : https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-scheduled-scaling.html#sch-actions_rules

Thanks

AWS
SUPPORT ENGINEER
answered a year ago

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