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I have an API Gateway with Lambdas behind, for some of the endpoints I want to schedule an execution in the future, to run once, for example the REST call was made at T time, I want that lambda to schedule an execution ONCE at T+20min.
The only solution I found to achieve this is to use boto3 and Cloudwatch to setup a cron at the moment the REST call was made, send an event with the payload, then when the delayed lambda runs, it removes the rule.
I found this very heavy, is there any other way to achieve such pattern ?
Edit: It is NOT A RECURRING Lambda, just to run ONCE.
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Create a Lambda that consumes an SQS message and returns an error. Add the waiting queue as a trigger to this lambda. Execution Queue: Add the execution queue as a trigger to your Lambda (that you want to schedule). Then, to schedule your lambda you need to simply post a message to the waiting queue.
This can be accomplished by setting a CloudWatch event rule to trigger your Lambda function. On each invocation of your Lambda function, the function will need to determine its next run time and modify the event rule appropriately.
To trigger a Lambda function once every 20 or 24 hours, we can schedule a trigger in CloudWatch Events. CloudWatch Events allows targets to be triggered using a Schedule Expression. A Schedule Expression can define a rate; for example, every 24 hours. Or can accept a standard cron job expression.
One option is to use AWS Step Functions to trigger the AWS Lambda function after a given delay.
Step Functions has a Wait state that can schedule or delay execution, so you can can implement a fairly simple Step Functions state machine that puts a delay in front of calling a Lambda function. No database required!
For an example of the concept (slightly different, but close enough), see:
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