What is the MOST secure way to configure this access for the Lambda function?
Create an IAM user that has permissions to access the DynamoDB table. Create an access key for this user. Store the access key ID and secret access key in the Lambda function environment variables.
Add a resource-based policy to the DynamoDB table to allow access from the Lambda function’s IAM role.
Create an IAM policy that allows access to the DynamoDB table. Attach this policy to the Lambda function’s IAM role.
Create a DynamoDB Accelerator (DAX) cluster. Configure the Lambda function to use the DAX duster to access the DynamoDB table.
Explanations:
Storing access key ID and secret access key in environment variables is not secure, as it exposes sensitive credentials. IAM users are typically not recommended for Lambda functions due to security risks and management overhead.
While a resource-based policy could allow access from the Lambda function’s IAM role, it’s generally less common and not the most straightforward or secure method compared to using IAM roles directly. Resource-based policies can add complexity in management.
Creating an IAM policy that allows access to the DynamoDB table and attaching it to the Lambda function’s IAM role is the most secure and recommended practice. This ensures that the Lambda function has the necessary permissions without hardcoding credentials, following AWS best practices for security.
Using a DynamoDB Accelerator (DAX) cluster does not inherently secure access to DynamoDB. DAX is a caching service that can enhance performance but does not provide a means for managing IAM permissions. Therefore, this option does not directly address secure access configuration.
I believe the answer is:
Create an IAM policy that allows access to the DynamoDB table. Attach this policy to the Lambda function’s IAM role.