Spot Fleet with Diversified Allocation Strategy – with Auto Scaling Enabled?

[virasana]

Hi All

How can a spot fleet have “auto-scaling enabled”. I understand that fleets do not enable auto scaling?

Many Thanks!

A company is hosting a multi-tier web application in AWS. It is composed of an Application Load Balancer and EC2 instances across three Availability Zones. During peak load, its stateless web servers operate at 95% utilization. The system is set up to use Reserved Instances to handle the steady-state load and On-Demand Instances to handle the peak load. Your manager instructed you to review the current architecture and do the necessary changes to improve the system.

Which of the following provides the most cost-effective architecture to allow the application to recover quickly in the event that an Availability Zone is unavailable during peak load?

ANSWER:
Launch a Spot Fleet using a diversified allocation strategy, with Auto Scaling enabled on each AZ to handle the peak load instead of On-Demand instances. Retain the current setup for handling the steady state load.

[JR-TutorialsDojo]

Hello virasana,

Thanks for reaching out to us.

Automatic scaling is supported for Spot Fleet through a combination of AWS services: Amazon EC2, CloudWatch, and Application Auto Scaling.

While Spot Fleet doesn’t have built-in Auto Scaling like ASGs, you can enable automatic scaling by:

• Creating a Spot Fleet request via Amazon EC2
• Defining CloudWatch alarms to monitor metrics like CPU utilization
• Configuring scaling policies using Application Auto Scaling

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-fleet-automatic-scaling.html

So, in the context of the given question, the answer refers to using a Spot Fleet with a diversified allocation strategy and enabling automatic scaling per AZ, which is entirely valid, even if the scaling mechanism is external to the fleet itself.

Hope that helps clarify!

Best regards,
JR @ Tutorials Dojo

[virasana]

Thank you,
Yes, I see that AutoScaling is in fact supported. Note that the fleet must be of type “maintain”, it must be registered as a scalable target and there must be appropriate CloudWatch alarms and IAM permissions in place:

– Video: https://youtu.be/rlYLbs33Ofs?si=WXDFV9UUuzQ19bVY
– AWS Docs:
– https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-fleet-automatic-scaling.html
– https://docs.aws.amazon.com/autoscaling/application/userguide/services-that-can-integrate-ec2.html

[JR-TutorialsDojo]

Glad the clarification helped! Thanks for adding those important details and resources.

Let us know if you need further assistance.

Best regards,
JR @ Tutorials Dojo