Question

A company processes order events published to an EventBridge custom event bus. A Lambda function is triggered by an EventBridge rule for every event, but the function only needs to act on events where 'detail.status' equals 'CANCELLED'. Currently the Lambda is invoked for all events and immediately exits for irrelevant ones, driving up invocation costs and cluttering CloudWatch metrics. The DevOps team must reduce unnecessary Lambda invocations while ensuring no CANCELLED events are missed. What is the MOST operationally efficient solution?

Accepted Answer

Add a content-based event pattern to the EventBridge rule that matches only events where 'detail.status' is 'CANCELLED', so the rule invokes Lambda solely for matching events.

Answer

Keep the existing rule and add code at the start of the Lambda function to check 'detail.status' and return early, then set reserved concurrency to limit invocations.

Answer

Create a CloudWatch Logs metric filter on the Lambda log group to count CANCELLED events and use a subscription filter to reprocess only those events.

Answer

Route all events to an SQS queue and configure the Lambda event source mapping with a filter criteria expression matching 'CANCELLED' status.