Serverless Local Schedule
This plugin allows you to specify a timezone on your lambdas and step functions triggered by AWS CloudWatch Events.
Install
npm i -D @distinction-dev/serverless-local-schedule
or
yarn add -D @distinction-dev/serverless-local-schedule
Add the plugin to your serverless.yml file
plugins:
- "@distinction-dev/serverless-local-schedule"
How it works
When you specify a schedule as an event in your serverless config, this plugin generates 6 different crons to deal with DST changes during that year like so:-
functions:
hello:
handler: handler.hello
events:
- schedule:
rate: cron(0 10 * * ? *)
timezone: America/New_York
functions:
hello:
handler: handler.hello
events:
- schedule:
rate: cron(0 15 * 1-2,12 ? *) # full non-DST months
- schedule:
rate: cron(0 15 1-10 3 ? *) # non-DST portion of March
- schedule:
rate: cron(0 14 11-31 3 ? *) # DST portion of March
- schedule:
rate: cron(0 14 * 4-10 ? *) # full DST months
- schedule:
rate: cron(0 14 1-3 11 ? *) # DST portion of November
- schedule:
rate: cron(0 15 4-31 11 ? *) # non-DST portion of November
Usage
Lambda Functions
functions:
hello:
handler: handler.hello
events:
- schedule:
rate: cron(0 10 * * ? *)
timezone: America/New_York
It works by converting that into 6 different schedules, effectively the same as having the following configuration:
functions:
hello:
handler: handler.hello
events:
- schedule:
rate: cron(0 15 * 1-2,12 ? *) # full non-DST months
- schedule:
rate: cron(0 15 1-10 3 ? *) # non-DST portion of March
- schedule:
rate: cron(0 14 11-31 3 ? *) # DST portion of March
- schedule:
rate: cron(0 14 * 4-10 ? *) # full DST months
- schedule:
rate: cron(0 14 1-3 11 ? *) # DST portion of November
- schedule:
rate: cron(0 15 4-31 11 ? *) # non-DST portion of November
Step Functions
stepFunctions:
stateMachines:
helloStepFunc:
events:
- schedule:
rate: cron(0 10 * * ? *)
timezone: America/New_York
It works by converting that into 6 different schedules, effectively the same as having the following configuration:
stepFunctions:
stateMachines:
helloStepFunc:
events:
- schedule:
rate: cron(0 15 * 1-2,12 ? *) # full non-DST months
- schedule:
rate: cron(0 15 1-10 3 ? *) # non-DST portion of March
- schedule:
rate: cron(0 14 11-31 3 ? *) # DST portion of March
- schedule:
rate: cron(0 14 * 4-10 ? *) # full DST months
- schedule:
rate: cron(0 14 1-3 11 ? *) # DST portion of November
- schedule:
rate: cron(0 15 4-31 11 ? *) # non-DST portion of November
Extra points to consider
-
To see what crontabs you'll get for your timezone, try https://distinction-dev.github.io/local-crontab/
-
The
- schedule: cron(* * * * ? *)
short syntax isn't supported. -
Unfortunately you cannot specify day of the week in the cron expression i.e.
cron(0 7 ? * MON-FRI *)
. This is because to support the split months (March & November in the US), the plugin has to specify a day of month (EG: November 1-3 in 2018), so you cannot specify a DOW other than?
unfortunately. Recommended workaround for this is to move the day of week check into your code so it's just a no-op on non weekdays for instance.
Debugging
A launch.json
file for vscode is provided which will run sls package
in the test service.
It will be useful if you would like to test and see how the plugin works or debug with your crontab or event configuration
History
Originally developed by Capital One, now maintained by Distinction Dev
This was maintained by Serverless Inc for some time and then forked over by Distinction Dev
Capital One considers itself the bank a technology company would build. It's delivering best-in-class innovation so that its millions of customers can manage their finances with ease. Capital One is all-in on the cloud and is a leader in the adoption of open source, RESTful APIs, microservices and containers. We build our own products and release them with a speed and agility that allows us to get new customer experiences to market quickly. Our engineers use artificial intelligence and machine learning to transform real-time data, software and algorithms into the future of finance, reimagined.