Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in how to securely provide sensitive credentials to serverless code without embedding secrets in code or exposing them unencrypted. In production, this is about knowing exactly how Lambda environment variables integrate with AWS KMS encryption and the risks of hardcoding secrets. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
Your company, NextGen Analytics, has a scheduled AWS Lambda function that must connect to a third-party API requiring an API key for authentication. The Lambda function runs automatically on a set schedule without human intervention. It’s critical to keep the API key encrypted when stored and decrypt it only at runtime.
The Requirement: #
You need to implement a solution that ensures the API key remains encrypted at rest but can be securely accessed by the Lambda function on execution.
The Options #
- A) Store the API key as a Lambda environment variable encrypted using an AWS KMS customer-managed key (CMK).
- B) Configure the application to prompt the user to provide the API key password on the first function invocation.
- C) Store the API key directly in the Lambda function code as a plain text string.
- D) Use Lambda@Edge functions and ensure all API communication uses HTTPS.
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Correct Answer #
A
Quick Insight: The Developer Imperative #
- Secure secrets at rest by leveraging Lambda environment variables encrypted with KMS—this is a native, scalable, and automated way.
- Avoid hardcoding secrets in code (Option C) risks exposure in version control and during deployment.
- Prompting for secrets at runtime (Option B) is not possible for fully automated Lambda executions.
- Lambda@Edge and HTTPS (Option D) relate to network security, not secret storage.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option A
The Winning Logic #
Storing the API key as an encrypted environment variable is the most secure and efficient approach in AWS Lambda contexts. Lambda environment variables support encryption using AWS KMS customer-managed keys, allowing the API key to be encrypted at rest automatically. At runtime, Lambda decrypts the variable for the function execution environment. This meets the requirement to keep the API key encrypted at rest while ensuring seamless access during execution without manual input.
The Trap (Distractor Analysis): #
- Why not B? Lambda functions run unattended on schedules; prompting for user input is impossible.
- Why not C? Hardcoding secrets in source code is a major security risk, often violates compliance, and complicates secret rotation.
- Why not D? Lambda@Edge and HTTPS only address secure transmission over the network, not secure storage of secrets.
The Technical Blueprint #
# Example: Encrypting environment variables with KMS for Lambda (CLI snippet)
aws lambda update-function-configuration \
--function-name NextGenAnalyticsScheduledJob \
--environment "Variables={API_KEY=your-api-key}" \
--kms-key-arn arn:aws:kms:region:account-id:key/key-id
Note: When configuring environment variables via the AWS Management Console, you can select a customer-managed KMS key to encrypt the variables automatically. Lambda handles decryption at invocation.
The Comparative Analysis #
| Option | API Complexity | Performance | Use Case |
|---|---|---|---|
| A | Medium (Env var + KMS) | High | Best for automated, secure secret storage |
| B | Low (manual input) | Low | Not suitable for scheduled Lambda |
| C | None (inline code) | High | Insecure; quick for PoC but poor practice |
| D | N/A (network related) | Medium | Irrelevant for secret storage |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick Lambda environment variables encrypted with KMS when you see serverless scheduled execution that requires secret credentials.
Real World #
In production, some teams additionally use AWS Secrets Manager or Parameter Store with encryption and automatic rotation, accessed programmatically by the Lambda function—this adds more security and facilitates secret rotation without code redeployment.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.