A developer deploys an AWS Lambda function that writes data to Amazon DynamoDB.

AWS Lambda automatically integrates with Amazon CloudWatch Logs, but logging only works if the function’s execution role has the correct IAM permissions. AWS documentation states that Lambda functions require permissions for logs:CreateLogGroup, logs:CreateLogStream, and logs:PutLogEvents to successfully publish log entries.

In this scenario, CloudWatch metrics show errors, which confirms that the function is executing. The absence of logs despite logging statements in the code strongly indicates a missing IAM permission issue, not a runtime or tracing issue.

CloudWatch Lambda Insights (Option B) provides performance metrics but does not enable basic logging. AWS X-Ray (Option C) provides distributed tracing but does not replace CloudWatch Logs. Option D is invalid because CloudWatch does not assume roles to collect logs.

AWS documentation explicitly identifies missing log permissions as the most common cause of absent Lambda logs. Therefore, granting the Lambda execution role the appropriate CloudWatch Logs permissions resolves the issue.