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Difficulty: MediumDeployment Strategies

A developer is updating a web application running on an AWS Elastic Beanstalk environment. The application is highly sensitive to customer-facing bugs, so the developer wants to test the new version using a small percentage of real production traffic (10%10\%) for a duration of 1515 minutes. If the new version triggers any Amazon CloudWatch alarms during this time, the traffic must immediately route back to the old version. If no alarms are triggered, the remaining 90%90\% of traffic should automatically shift to the new version. Which deployment policy should the developer configure in the Elastic Beanstalk environment?

  1. A
    All at once
  2. Traffic splittingAnswer
  3. C
    Immutable
  4. D
    Rolling with additional batch

Answer

Traffic splitting
Traffic splitting is the correct answer because it is the only native AWS Elastic Beanstalk deployment policy that allows developers to perform canary testing. It launches a temporary Auto Scaling group with the new version, routes a specified percentage of traffic (e.g., 10%10\%) to it for a set evaluation period (e.g., 1515 minutes), monitors health using CloudWatch alarms, and automatically rolls back if alarms are triggered, or promotes the deployment to 100\% traffic if successful.

Step-by-Step Solution

1
Analyze the requirement to route a small fraction (10%10\%) of live production traffic to a new version of the application for validation.
Identify that this represents a canary deployment pattern, which requires splitting load balancer traffic between the existing environment and a new deployment.
This rules out standard rolling, rolling with additional batch, and immutable deployment policies, which update instances without fractional traffic routing.
2
Evaluate the rollback and promotion criteria (1515 minutes of evaluation using CloudWatch alarms, followed by automatic promotion or rollback).
Determine that the deployment policy must natively support CloudWatch alarm monitoring and automated rollback/promotion based on health status.
Traffic Splitting in Elastic Beanstalk allows configuring a specific evaluation time (e.g., 1515 minutes) and linking CloudWatch alarms to trigger a rollback.
3
Select the Elastic Beanstalk deployment policy that matches these constraints.
The Traffic Splitting policy is chosen as it is the only native Elastic Beanstalk policy designed specifically for percentage-based traffic shifting and automatic CloudWatch-based rollbacks.
Other policies like Immutable and Rolling with additional batch do not support fractional traffic splitting.

Key Concept

AWS Elastic Beanstalk Traffic Splitting Deployment Policy
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Topics

Deployment Strategies

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