AWS DVA-C02 Drill: API Gateway Versioning - Managing Lambda Integration Environments

Jeff’s Note

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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 properly managing multiple API versions without introducing brittle routing logic inside Lambda functions. In production, this is about knowing exactly how to leverage API Gateway’s native features—such as stages and stage variables—to cleanly separate environments and avoid muddying your Lambda code with versioning concerns. Let’s drill down.

The Certification Drill (Simulated Question)

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Scenario

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A fintech startup called VelocityPay is building a RESTful payment processing API using Amazon API Gateway integrated with AWS Lambda functions. Their engineering team wants to run different API versions simultaneously in production to support A/B testing and gradual feature rollouts without code complexity inside Lambda.

The Requirement:

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What is the BEST method to deploy and operate multiple API versions within API Gateway and ensure Lambda functions receive the correct versioning context?

The Options

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• A) Use a custom X-Version HTTP header to indicate which API version to invoke and pass this header to the Lambda functions.
• B) Implement an API Gateway Lambda authorizer that routes clients to the appropriate API version.
• C) Apply API Gateway resource policies to isolate API versions and provide versioning context to Lambdas.
• D) Deploy different API versions as unique API Gateway stages with separate endpoints, and use stage variables to give additional context to Lambda functions.

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Correct Answer

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D

Quick Insight: The Developer Imperative

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Using stage variables coupled with distinct stages (versions) provides a clean, maintainable, and scalable way to manage different API versions. It keeps routing logic out of Lambda code and leverages built-in API Gateway versioning mechanics.

Content Locked: The Expert Analysis

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You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?

The Expert’s Analysis

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Correct Answer

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Option D

The Winning Logic

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Deploying multiple API versions as uniquely named stages (e.g., dev, test, v1, v2) creates isolated, version-specific endpoints. Using stage variables allows you to inject configuration or version metadata that the Lambda functions can consume as environment variables or part of the event input. This design cleanly separates concerns between deployment/versioning and Lambda business logic. It is a best practice recommended by AWS for multi-version API management.

The Trap (Distractor Analysis):

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• Why not A?
  Relying on an X-Version header requires all clients to explicitly set this header correctly every time, increasing risk of errors. It also forces your Lambda to include complex routing logic, violating separation of concerns.

• Why not B?
  Lambda authorizers are meant for authorization and authentication, not for routing or version control. Repurposing them for version routing adds unnecessary latency and complexity.

• Why not C?
  API Gateway resource policies control access permissions, not version routing or contextual metadata passing. They cannot inform Lambdas which version is invoked meaningfully.

The Technical Blueprint

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# Example AWS CLI for creating stage variables linked to Lambda alias/version per stage
aws apigateway create-deployment \
    --rest-api-id a1b2c3d4e5 \
    --stage-name v1 \
    --stage-description "Version 1 deployment" \
    --variables lambdaAlias=prod

aws apigateway create-deployment \
    --rest-api-id a1b2c3d4e5 \
    --stage-name v2 \
    --stage-description "Version 2 deployment" \
    --variables lambdaAlias=canary

In your Lambda integration, you can then reference ${stageVariables.lambdaAlias} to invoke the correct Lambda alias/version.

The Comparative Analysis

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Real-World Application (Practitioner Insight)

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Exam Rule

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For the exam, always pick API Gateway stages with stage variables when you see “multiple API versions” or “versioned deployments” in the context of Lambda integrations.

Real World

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In production, teams often use API Gateway stages alongside Lambda aliases to deploy canary releases and blue/green updates without touching client code or polluting Lambda handlers with conditional logic.

(CTA) Stop Guessing, Start Mastering

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Disclaimer

This is a study note based on simulated scenarios for the AWS DVA-C02 exam.