AWS Cloudwatch event - how to trigger for different timezones?

Question

I've got a bunch of AWS Lambda functions that I want to trigger at certain times of day, but those times are in different timezones. For example, I might want events to trigger at:

• 4:55pm Sydney time
• 6:30pm Chicago time
• 9pm Chicago time

...and so on.

Using Cloudwatch events, regardless of which AWS region I use, it seems that I can only specify events to trigger using UTC (i.e. London time). For today, that's fine; I can work out the time differences between London and Sydney, and London and Chicago, and so on - however, summer time comes into effect on different dates in different cities, and it'll cause my Lambdas to trigger at the wrong times when it does.

Is there a way to trigger these Cloudwatch events using non-UTC time settings? Alternately, is there a mechanism other than Cloudwatch that I can use to trigger Lambda functions at specific times of day, AND specify those times in the timezone I want?

Thanks in advance

Answer 1

Be careful - London is currently (as of 6 February, 2017) UTC but, starting on the 26th of March 2017, they will be in BST - British Summer Time which will be UTC + 1. In other words, London time is not necessarily UTC.

To me, the best bet is to have another lambda update the cloudwatch trigger time based on known timezone changes. You don't show your implementation language but, as an example, in Java you could take a look at this post. Run this Lambda once a day at UTC time zero and update the cloudwatch rule times appropriately.