Get (exact) scheduled cron time in lambda

Serverless Framework
1

Hi-

I’ve got a use case where I need to run a scheduled lambda via cron periodically, like every 15 minutes, and I need to query a DynamoDB table to for entries where the key is the exact epoch when the cron was scheduled to run. For example, if the lambda is scheduled to run at
1/1/22 09:15:00, I need that epoch, and not the current time when the lambda is actually started (typically a few seconds later). Is there any way to get that “scheduled time” in the lambda function?

Alternatively it seems like I can probably take the current time and round it down to the 15 minute interval. Annoying, but not the end of the world I guess as long as the lambda never starts BEFORE the scheduled time. I assume that it always runs at or slightly after the scheduled time.

I really thought I saw this information in the past, but I can’t seem to find it in any of my current lambda cron logs…

Any suggestions would be appreciated.

Thanks!

2

The event data passed to the lambda from the CloudWatch schedule includes an event time. Here is a sample of what CloudWatch passes:

{
  "id": "cdc73f9d-aea9-11e3-9d5a-835b769c0d9c",
  "detail-type": "Scheduled Event",
  "source": "aws.events",
  "account": "123456789012",
  "time": "1970-01-01T00:00:00Z",
  "region": "us-east-1",
  "resources": [
    "arn:aws:events:us-east-1:123456789012:rule/ExampleRule"
  ],
  "detail": {}
}

I haven’t used the time field myself but I believe it is when the trigger fired.

3

Hi, thanks for sharing.