求助：AWS Lambda被CloudWatch定时事件异常高频触发问题

Let’s break down the most likely causes and fixes for your issue—since your CloudWatch Event trigger shows it’s firing as expected but Lambda is being called way more often than your 5-minute schedule:

1. Check for Duplicate CloudWatch Event Rules #

• It’s surprisingly easy to accidentally create multiple rules targeting the same Lambda function. Head to the CloudWatch Events console, filter rules by your Lambda as the target, and confirm only one active rule exists with your 0/5 * * * ? * cron schedule.
• Don’t forget to check for old rules that might’ve been disabled but re-enabled by mistake, or even rules using rate expressions (like rate(1 minute)) that you might’ve forgotten about.

2. Investigate Async Invocation Retries #

• If your Lambda function is failing (even silently, like unhandled exceptions), AWS automatically retries async invocations twice by default. Check your Lambda’s Error metric in CloudWatch—if you see non-zero errors, that’s almost certainly why you’re seeing extra calls.
• You can adjust this behavior: go to your Lambda’s Configuration tab > Asynchronous invocation, tweak the retry attempts, or set up a dead-letter queue (DLQ) to catch failed invocations instead of letting them retry.

3. Look for Unintended Trigger Sources #

• Lambda can be invoked by way more than just CloudWatch Events. Check your Lambda’s Triggers tab—are there other triggers like SQS queues, API Gateway endpoints, S3 bucket events, or even AWS Step Functions pointing to it?
• If you don’t see anything obvious, dig into the Lambda execution logs. Each invocation’s event payload includes a source field that tells you where the call came from (e.g., aws.events for CloudWatch, aws.s3 for S3). This will immediately reveal if another service is triggering your Lambda.

4. Validate CloudWatch Event Target Settings #

• Sometimes a single CloudWatch rule might be configured with multiple targets pointing to the same Lambda, or set to retry failed invocations. Go to your rule’s Targets section, confirm only one target exists for your Lambda, and check if retry attempts are enabled for the target.
• If the rule’s target has retries turned on, a failed invocation attempt from CloudWatch will trigger another call, leading to extra executions.

5. Check for Throttling or Concurrency Backlogs #

• If your Lambda is hitting concurrency limits or getting throttled, CloudWatch might queue up invocations that get processed all at once once capacity is available. Check the Throttles metric in Lambda’s CloudWatch dashboard—if you see throttles, increasing reserved concurrency temporarily might resolve the burst of invocations.

6. Deep-Dive into Log Timestamps #

• Pull up your Lambda’s CloudWatch Logs and note the exact timestamp of each invocation. Compare these to the CloudWatch Event rule’s firing timestamps (you can find these in the rule’s dedicated log group under CloudWatch Logs).
• Look for patterns: are extra invocations happening right after a failed execution? Do they line up with a different schedule? This will help you narrow down whether it’s retries, duplicate rules, or an external trigger causing the issue.

内容的提问来源于stack exchange，提问作者Sebastien H.