AWS CloudWatch Events Rules use the UTC time zone. If we need a rule to trigger at a some local DST time, we must update the schedule expressions twice a year. Manually updating the schedule expressions is time consuming and error prone.

We can make this a bit easier by having 2 sets of rules, one set is enabled when there is DST and the other when there is no DST.

• my-five-o-clock-rule-enable-for-dst
• my-five-o-clock-rule-enable-for-no-dst

The update process is now a bit simpler and less error prone - search for -for-dst or -for-no-dst and enable or disable each set. We could also do this through the CLI or an AWS Lambda - enable the set that ends with one suffix and disable the other set.

AWS CloudFormation

If our stack is set up by CloudFormation scripts, we include both rules in our cloudformation script and pick up the State from a bupotato.peelings@gmail.comild variable. The DST switch then becomes 2 steps

1. Run the lambda to toggle between the -dst and -no-dst sets.
2. Change the build variable so that new deployments enable the right set.