AWS Spot Instance: What It Is and How It Works

An AWS Spot Instance is a type of virtual server that lets you use spare computing capacity at a lower price than regular instances. These instances can be interrupted by AWS when the capacity is needed elsewhere, making them ideal for flexible, fault-tolerant workloads.

How It Works

Think of AWS Spot Instances like renting a car from a shared fleet that has extra cars available at a discount. AWS has unused servers and offers them at lower prices, but they can take the car back anytime they need it. You get to use the server as long as AWS doesn't reclaim it.

This means your Spot Instance can run at a much lower cost, but it might stop running if AWS needs the capacity for other customers. You can set your maximum price and AWS will run your instance when the current Spot price is below your limit.

Example

This example shows how to request a Spot Instance using AWS CLI with a simple JSON configuration.

bash

aws ec2 request-spot-instances --spot-price "0.03" --instance-count 1 --type "one-time" --launch-specification '{"ImageId":"ami-0abcdef1234567890","InstanceType":"t3.micro"}'

Output

{
    "SpotInstanceRequests": [
        {
            "SpotInstanceRequestId": "sir-12345678",
            "State": "open",
            "Status": {
                "Code": "pending-evaluation",
                "Message": "Your Spot request is being evaluated."
            }
        }
    ]
}

When to Use

Spot Instances are great when you want to save money and your work can handle interruptions. For example, batch processing, big data analysis, or testing environments where stopping and restarting is okay.

They are not ideal for critical applications that must run continuously without interruption.

Key Points

• Spot Instances offer up to 90% cost savings compared to regular instances.
• They can be interrupted with a two-minute warning when AWS needs capacity.
• You can set a maximum price to control costs.
• Best for flexible, fault-tolerant workloads.

Key Takeaways

AWS Spot Instances let you use spare capacity at a lower cost but can be interrupted anytime.

They are ideal for workloads that can handle sudden stops and restarts.

You set a maximum price and AWS runs your instance when the Spot price is below it.

Spot Instances can save up to 90% compared to regular on-demand instances.

Not suitable for critical applications needing guaranteed uptime.