Spot Instances

💡 Definition

Amazon EC2 Spot Instances let you take advantage of unused EC2 capacity in the AWS cloud. Spot Instances are available at up to a 90% discount compared to On-Demand prices.

🔑 Key Concepts

• Spare Capacity: You are bidding on unused AWS server capacity.
• Interruption: AWS can terminate your Spot Instance with a 2-minute warning if they need the capacity back.
• Price: The Spot price fluctuates based on supply and demand (but you never pay more than your max price).

⚙️ How it Works

1. Request: You request Spot capacity, specifying a max price you are willing to pay.
2. Launch: If your price > current Spot price, your instance launches.
3. Run: It runs as long as capacity is available and your price > Spot price.
4. Interrupt: If AWS needs capacity, you get a 2-minute warning via instance metadata/EventBridge to save work/hibernate.

🎯 Use Cases

• Fault-Tolerant Workloads: Batch processing, big data analysis, CI/CD pipelines.
• Stateless Web Servers: Behind a load balancer where losing a node is acceptable.
• Testing/Development: Running large scale tests cheaply.

💰 Pricing Model

• Market Price: You pay the current Spot price (which updates every 5 mins).
• Massive Discount: Up to 90% off On-Demand.

📝 Exam Tips (CLF-C02)

• Key characteristic: Can be interrupted.
• Use for stateless, fault-tolerant, flexible applications.
• Not for critical databases or applications that cannot handle downtime.
• Spot Block: (Deprecated feature, but concept remains) Requesting for a fixed duration (1-6 hours) without interruption is no longer the standard way; standard Spot is now the focus.

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See Also: * EC2 * Auto Scaling