Clarification: Review Mode Set 1 – Q1

[r-v]

Question asks for “automatic rollback” of deployment in case of failure.

“Correct Answer” says setup lambda function alias with weighted routing. How is this automatic rollback?

Does lambda automatically stop sending traffic to new version if there are errors even when alias still says send 20% traffic to new version?
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1. QUESTION

Category: DOP – High Availability, Fault Tolerance, and Disaster Recovery

The company is re-architecting its monolithic system to a serverless application in AWS to save on cost. The deployment of the succeeding new version of the application must be initially rolled out to a small number of users first for testing before the full release. If the post-hook tests fail, the system should automatically roll back the deployment. The DevOps Engineer was assigned to design an efficient deployment setup that mitigates any unnecessary outage that impacts their production environment.

As a DevOps Engineer, how should you satisfy this requirement? (Select TWO)

[r-v]

One of the “correct answers” : Set up one AWS Lambda Function Alias that points to both the current and new versions. Route 20% of incoming traffic to the new version and once it is considered stable, update the alias to route all traffic to the new version.

[r-v]

Do you mean we should use a lambda weighted alias in combination with a canary deployment on api gateway? doesnt sound right / necessary.

Second correct answer: Set up a canary deployment in Amazon API Gateway that routes 20% of the incoming traffic to the canary release. Promote the canary release to production once the initial tests have passed.

[TutorialsDojo-Support]

Hello r-v,

Thanks for the feedback. I’ll try to answer your questions.

“Correct Answer” says setup lambda function alias with weighted routing. How is this automatic rollback?

Does lambda automatically stop sending traffic to new version if there are errors even when alias still says send 20% traffic to new version?

>> I agree that this answer does not provide automatic rollback. So our team will review and revise the question to remove the “automatic” part on the requirement.

One of the “correct answers” : Set up one AWS Lambda Function Alias that points to both the current and new versions. Route 20% of incoming traffic to the new version and once it is considered stable, update the alias to route all traffic to the new version.

Second correct answer: Set up a canary deployment in Amazon API Gateway that routes 20% of the incoming traffic to the canary release. Promote the canary release to production once the initial tests have passed.

Do you mean we should use a lambda weighted alias in combination with a canary deployment on api gateway? doesnt sound right / necessary.

>> Not necessarily a combination of the two. These 2 answers are independent of each other. You can implement either of the correct answers to achieve the canary deployment needed for the question.

This scenario wants you to explore the two options that you have if you want to have canary deployments for Lambda functions. You can use Lambda Aliases if you have 2 versions of your Lambda function, you can control how much traffic is sent to the new version. If the testing fails, you can quickly adjust the traffic percentage to effectively roll back to the old version.

You can employ a similar technique using API gateway. You can create a separate stage for your new version and then adjust the traffic percentage on the canary release deployment. If you see any problems on the canary deployment, you can easily roll back the deployment from API Gateway.

See this link for more information. https://docs.aws.amazon.com/apigateway/latest/developerguide/canary-release.html

Hope this helps. If you have any other concerns, we’d be happy to hear it.

Regards,

Kenneth Samonte @ Tutorials Dojo