A company is using Amazon OpenSearch Service to implement an audit monitoring system. A developer needs to create an AWS CloudFormation custom resource that is associated with an AWS Lambda function to configure the OpenSearch Service domain. The Lambda function must access the OpenSearch Service domain by using OpenSearch Service internal master user credentials.
What is the MOST secure way to pass these credentials to the Lambda function?
A Use a CloudFormation parameter to pass the master user credentials at deployment to the OpenSearch Service domain’s MasterUserOptions and the Lambda function’s environment variable. Set the NoEcho attribute to true. B Use a CloudFormation parameter to pass the master user credentials at deployment to the OpenSearch Service domain’s MasterUserOptions and to create a parameter in AWS Systems Manager Parameter Store. Set the NoEcho attribute to true. Create an IAM role that has the ssm:GetParameter permission. Assign the role to the Lambda function. Store the parameter name as the Lambda function’s environment variable. Resolve the parameter’s value at runtime. C Use a CloudFormation parameter to pass the master user credentials at deployment to the OpenSearch Service domain’s MasterUserOptions and the Lambda function’s environment variable. Encrypt the parameter’s value by using the AWS Key Management Service (AWS KMS) encrypt command. D Use CloudFormation to create an AWS Secrets Manager secret. Use a CloudFormation dynamic reference to retrieve the secret’s value for the OpenSearch Service domain’s MasterUserOptions. Create an IAM role that has the secretsmanager:GetSecretValue permission. Assign the role to the Lambda function. Store the secret’s name as the Lambda function’s environment variable. Resolve the secret’s value at runtime. Show Answer Answer Explanation AWS Secrets Manager with a CloudFormation dynamic reference is the most secure pattern. The secret is stored encrypted; Lambda retrieves it at runtime using an IAM role with secretsmanager:GetSecretValue permissions; and the secret name is stored as an environment variable to avoid hardcoding. This approach follows AWS best practices for credential management, supports rotation, and avoids exposure in code or deployment logs. Other options risk exposing credentials in CloudFormation or parameter stores.
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