SOA-C02 Deployment, Provisioning, and Automation Practice Question
A SysOps administrator uses AWS CloudFormation to manage a stack that includes an Amazon EC2 instance. The administrator wants to update the instance type from t3.medium to t3.large without recreating the instance. The instance type change is supported as a simple update in CloudFormation. Which stack update method should the administrator use to apply this change with the least disruption?
⚠ Common exam trap
Candidates often assume a change set is required for all updates or that it reduces disruption, when in fact it is only a review mechanism and does not change the update behavior; the direct update is equally safe and faster for simple, supported changes.
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
✓
Directly update the stack by modifying the template and submitting the update via the AWS Management Console, AWS CLI, or API.
Changing an EC2 instance type from t3.medium to t3.large is a supported simple update in CloudFormation, meaning the resource can be updated in-place without replacement. By directly updating the stack via the AWS Management Console, AWS CLI, or API, the administrator applies the change immediately with minimal disruption, as CloudFormation will stop the instance, modify the instance type, and restart it. This method avoids the overhead of creating a change set or deleting and recreating the stack, which would cause unnecessary downtime or complexity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Directly update the stack by modifying the template and submitting the update via the AWS Management Console, AWS CLI, or API.
Why this is correct
A direct stack update is the correct method because CloudFormation compares the modified template against the current stack and applies the changed InstanceType property to the existing EC2 instance without replacement. The update can be submitted via the AWS Management Console, AWS CLI, or API, and because this is a simple, in-place attribute change, it minimizes downtime and avoids extra operational overhead. This approach is the fastest and least disruptive way to achieve the desired configuration.
- ✗
Create a change set to review the changes, then execute the change set.
Why it's wrong here
Creating a change set adds an unnecessary intermediate step for a simple, low-risk modification like changing an instance type. The change set would only preview the exact same update that a direct stack update would perform, and executing it does not reduce the operational impact or improve safety for this scenario. While change sets are valuable for reviewing complex or potentially destructive updates, they are not the most efficient choice here because the change is straightforward and does not require replacement.
- ✗
Apply a stack policy to the EC2 instance to allow the update, then update the stack.
Why it's wrong here
A stack policy restricts updates to protected resources but does not enable in-place modification of an EC2 instance type; the instance type change requires a direct stack update that modifies the resource property, and applying a policy alone does not trigger that property change. This option is tempting because stack policies are designed to prevent accidental updates or deletions of critical resources, and in a scenario where the administrator wanted to block any changes to the instance, a stack policy would be the correct choice.
- ✗
Delete the existing stack and create a new stack with the updated instance type.
Why it's wrong here
Deleting the existing stack and creating a new one would terminate the EC2 instance, which would cause an availability outage and potentially lose data stored on instance store volumes or any non-persistent resources. This approach also requires recreating all dependant resources and reconfiguring the environment from scratch, making it unnecessarily destructive and time-consuming. Because the instance type can be changed directly through a stack update without replacement, this method is an overreaction to a simple configuration change and is not the least disruptive option.
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