A subscription filter sends CloudWatch Logs events to a Firehose delivery stream that writes to S3. The team needs to drop noisy records and reshape the rest before they are stored in S3. What should the team configure?
Show answer and explanation
Answer: B
Kinesis Data Firehose supports record transformation through an invoked Lambda function. Firehose sends each batch to the function, which can drop, enrich or reformat records by returning a status for each one. The transformed output is then delivered to the destination, so unwanted records never reach S3.
Why the other options are wrong
- A. Metric filters turn log lines into metrics for alarms. They do not change the log events that are delivered to S3.
- C. S3 Object Lambda transforms objects when they are read, not when they are written, so the noisy records would already be stored.
- D. Glue crawlers infer schemas for cataloging. They do not filter or transform records moving through a delivery stream.