Cost-Optimized ECS Fargate High Availability Strategy

SAA-C03 By islever Editorial Last updated

Design cost-optimized compute solutions.

Short answer

D Configure an ECS capacity provider with Fargate and use AWS Compute Optimizer to rightsize the task definitions.

Question

A company runs its customer-facing web application on containers. The workload uses Amazon Elastic Container Service (Amazon ECS) on AWS Fargate. The web application is resource intensive. The web application needs to be available 24 hours a day, 7 days a week for customers. The company expects the application to experience short bursts of high traffic. The workload must be highly available. Which solution will meet these requirements MOST cost-effectively?
  1. Configure an ECS capacity provider with Fargate. Conduct load testing by using a third-party tool. Rightsize the Fargate tasks in Amazon CloudWatch.
  2. Configure an ECS capacity provider with Fargate for steady state and Fargate Spot for burst traffic.
  3. Configure an ECS capacity provider with Fargate Spot for steady state and Fargate for burst traffic.
  4. Configure an ECS capacity provider with Fargate. Use AWS Compute Optimizer to rightsize the Fargate task. Correct Answer

Key Takeaways

The exam trap is assuming Spot instances are always the answer for 'cost-effective' scaling, ignoring the explicit '24/7 availability' constraint that rules out interruptions.

This question tests how to balance high availability and cost optimization for resource-intensive web applications on AWS Fargate using capacity providers.

Common mistake: Candidates often choose Option B because it uses cheaper Spot instances for bursts, failing to recognize that Spot interruptions violate the strict availability requirement.

Expert Analysis

Why the Answer Is Correct

Option D is the correct answer because it addresses both the high availability and cost optimization requirements without violating the 24/7 uptime constraint. While Option B seems attractive due to lower costs, Fargate Spot instances can be interrupted with only two minutes of notice, which directly conflicts with the requirement for the workload to be available 24 hours a day, 7 days a week. Option D leverages AWS Compute Optimizer to rightsize tasks, ensuring you pay only for the resources you need, thereby optimizing costs while maintaining the reliability of standard Fargate instances.

Why the Other Options Are Wrong

Options B and C involve Fargate Spot, which introduces a risk of interruption. Since the application must be available 24/7, any potential downtime or forced eviction of Spot instances makes these options non-compliant with the availability SLA. Option A suggests conducting load testing and rightsizing via CloudWatch; while useful for initial setup, it lacks the automated, continuous optimization mechanism provided by AWS Compute Optimizer, making it less effective for ongoing cost management compared to Option D.

Community Comment Notes

Many learners initially favored Option B due to the significant cost savings associated with Spot instances, as noted by users like LeonSauveterre who argued for dynamic scaling. However, the majority correctly identified that the '24/7 availability' phrase is a critical keyword that excludes Spot. Comments from users like Liongeek and EllenLiu highlighted that Spot interruptions make it unsuitable for strictly available workloads, reinforcing the choice of Option D.

Exam Strategy

Always prioritize availability constraints over cost when they conflict. If a question specifies 'highly available' or '24/7', avoid solutions involving Spot instances or other interruptible components unless explicitly stated otherwise.

Frequently Asked Questions

Can Fargate Spot be used for burst traffic if availability is not 100%?

Yes, Fargate Spot is ideal for fault-tolerant, flexible schedule, or stateless batch jobs where interruptions are acceptable.

Does AWS Compute Optimizer automatically scale Fargate tasks?

No, it provides recommendations for vCPU and memory limits; you must adjust task definitions manually or via automation based on its advice.

More SAA-C03 FAQ →

Community Votes

D
56%
B
44%

56% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 14 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 14

  1. spoved 👍 4 Answered D
    https://aws.amazon.com/blogs/aws-cloud-financial-management/how-to-take-advantage-of-rightsizing-recommendation-preferences-in-compute-optimizer/ be available 24 hours a day, 7 days a week must be highly available => D
  2. flaviobrf 👍 4 Answered B
    B is the right choice, the application must be available 24/7
  3. Liongeek 👍 3 Answered D
    It's D. Compute Optimizer supports recommendations for Fargate Tasks https://aws.amazon.com/about-aws/whats-new/2022/12/aws-compute-optimizer-amazon-ecs-services-aws-fargate/ Option B and C recommend Spot, but that's not an option since the the question asks for 24x7 availability.
  4. rosanna 👍 3 Answered D
    spots might be interrupted and the questions says it has to be available 24/7, rightsizing addresses the cost optimization point but the spot is so risk so I'll go for D
  5. EllenLiu 👍 3 Answered D
    available for 24 * 7, spot is out as it can be interrupted any time.
Show 9 more comments
  1. LeonSauveterre 👍 2 Answered B
    A - It doesn't address the cost optimization for burst traffic. Rightsizing ensures you're not over-provisioning your baseline resources, but it doesn't provide a mechanism to dynamically scale up with cost-effective Spot instances during traffic spikes. B - The application can scale up quickly with Fargate Spot tasks to handle the increased load, and if a Spot task is interrupted, the remaining Fargate tasks can continue to serve traffic (and the system can try to acquire new Spot capacity). C - Fargate Spot is not recommended for steady-state workloads because it can be interrupted. This would compromise the application’s 24/7 availability. D - Like A, it fails to leverage Fargate Spot for cost savings. Combining Fargate for steady state with Fargate Spot for burst traffic, the 24/7 HA is actually guaranteed.
  2. dhewa 👍 2 Answered B
    This combination leverages the cost benefits of Fargate Spot for burst traffic while ensuring steady performance with regular Fargate instances.
  3. thiahthura 👍 2 Answered D
    D is right answer. Company desire is 24 * 7. So I think spot should be.
  4. Sarayounisaldossary 👍 1 Answered B
    Use Fargate Spot for burst traffic — it’s significantly cheaper (up to 70% savings) ECS Capacity Providers let you define a mix strategy for both types of compute This solution provides: High availability via regular Fargate- Cost savings (via Spot)- Scalability for traffic bursts without manual management why other options are incorrect? A. Only uses standard Fargate with performance tuning tools. Does not address cost optimization or scaling for traffic bursts. No use of Fargate Spot, which misses out on potential savings. C. Using Fargate Spot for steady-state workloads is not reliable. Spot tasks can be interrupted at any time, which is not acceptable for a 24/7 high-availability app. D. AWS Compute Optimizer helps with right-sizing but doesn't handle scaling or burst traffic.
  5. BugsyWarribwoy 👍 1 Answered B
    B is the valid answer. Use Fargate for steady-state tasks to ensure high availability and reliability, and Fargate Spot for burst tasks to handle high traffic at a reduced cost. This combination meets the requirements most cost-effectively. D is wrong because rightsizing alone does not optimize for burst traffic scenarios or reduce costs as effectively as incorporating Fargate Spot.
  6. FlyingHawk 👍 1 Answered B
    https://repost.aws/knowledge-center/fargate-spot-termination-notice B is correct as you can use ECS task draining to gracefully handle Spot interruptions.
  7. dfgdsfgfdgreg 👍 1 Answered B
    Compute Optimizer can not optimise fargate tasks.
  8. swati1508 👍 3
    B- for short work use spot
  9. pujithacg8 👍 3
    B is the right answer

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