Lambda async invocation with no reserved concurrency (retry-storm risk)

What it checks

Lambda async invocation with no reserved concurrency (retry-storm risk)

Where it applies

Terraform: aws_lambda_function

CloudFormation: AWS::Lambda::Function

How to fix it

1. Size a reservation using ConcurrentExecutions, request rate, duration and downstream capacity. A reservation is both a cap and capacity withheld from the shared pool. Async function errors normally retry twice; throttling/system errors use backoff for up to six hours by default, configurable through event-invoke settings. Retries do not imply an equal number of concurrent executions.

Frameworks

• AWS Well-Architected REL.5

These mappings are advisory, not an attestation of compliance.

Vendor documentation

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