DVA-C02 Deployment Practice Question
A developer is deploying a microservices application on Amazon ECS with the Fargate launch type. The application uses an Application Load Balancer (ALB) to route traffic. The developer wants to perform a blue/green deployment with automated traffic shifting using AWS CodeDeploy. What is the minimum number of target groups required for this deployment?
⚠ Common exam trap
Many exam-takers confuse blue/green deployments with canary deployments or assume that a single target group with multiple ports can serve both environments, but AWS CodeDeploy for ECS explicitly requires two distinct target groups to manage traffic shifting and rollback.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Two
In a blue/green deployment with AWS CodeDeploy and an Application Load Balancer (ALB) on Amazon ECS (Fargate), two target groups are required: one for the 'blue' (current) environment and one for the 'green' (new) environment. CodeDeploy shifts traffic from the blue target group to the green target group by updating the ALB listener rules, allowing zero-downtime deployments and automated rollback if needed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
One
Why it's wrong here
A single target group is insufficient for a blue/green deployment strategy because it can only route traffic to a single, active set of tasks at any given time. Blue/green deployments require the ability to maintain two distinct environments (the current "blue" version and the new "green" version) simultaneously, allowing for traffic shifting and rollback capabilities. A single target group cannot independently manage and switch between these two separate task sets.
- ✓
Two
Why this is correct
For a successful blue/green deployment with AWS CodeDeploy and ECS, two distinct target groups are essential. One target group is initially associated with the "blue" (current production) task set, while the second target group is associated with the "green" (new version) task set. AWS CodeDeploy orchestrates the traffic shift by updating the listener rules on the Application Load Balancer (ALB) to gradually or instantly direct traffic from the blue target group to the green target group. This setup facilitates seamless cutovers and provides a straightforward rollback mechanism.
- ✗
Three
Why it's wrong here
While a third target group could be used in more complex scenarios, such as for a canary release or a dedicated test environment, it is not a fundamental requirement for a standard blue/green deployment. The core mechanism of blue/green involves switching traffic between two complete environments. Introducing an unnecessary third target group for the primary traffic shift adds complexity without providing additional benefit for the basic blue/green pattern.
- ✗
Four
Why it's wrong here
Utilizing four target groups for a standard blue/green deployment on ECS with CodeDeploy is excessive and introduces unwarranted architectural complexity. The fundamental design of blue/green traffic shifting relies on having two distinct environments, each backed by its own target group. More than two target groups would complicate the listener rule configuration on the ALB and the CodeDeploy deployment group setup, making management and troubleshooting more difficult without enhancing the core blue/green functionality.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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