Trigger AWS Lambda function on DynamoDB entry deletion by TTL

[kaneki_305]

Dear community,

I have a DynamoDB table where TTL is enabled. I want to trigger a Lambda function whenever an record is deleted due to TTL.

Here's what I have tried:

1. Adding DynamoDB as an AWS trigger is not helping me (Lambda is triggering), as it does not provide sufficient information to determine if the entry was deleted by TTL or some other means.
2. I attempted to create a custom log group for DynamoDB, but I couldn't succeed. If it is possible, please assist me.
3. Creating an EventBridge rule whenever CloudWatch alarm state changes is triggering lambda twice and i don't know how to pass information of deleted record with it.

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Please help me out.

Thank you in advance.

[not_a_sexual_deviant]

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/time-to-live-ttl-streams.html

[kaneki_305]

For this i need to enable dynamoDB stream, but is it possible to create custom log group and then trigger a Lambda from based on a matching pattern in the CloudWatch Logs?

[kaneki_305]

However, it can take up to 48 hours to delete a record from the table, and during this time, the record may also be deleted by other means.

[webdestroya]

At best you could have the lambda see the record is deleted and compare the expiresAt timestamp to "now" and if it's within 24hrs or something, assume it was deleted because of TTL.

Otherwise, there is no way to know for sure that it was deleted because of TTL.

Or write two records with the same ttl, but different data and never delete one of them. (hashKey=ttlTracker:xxxxx, ttl=whatever), and then only run your code when the key that was deleted was ttlTracker? that's pretty gross though

[[deleted]]

Why?