TOPIC CLOUD
Spot Instances cheap machines that vanish
IN 10 SECONDS
Spot (or preemptible) instances let you bid on unused cloud compute capacity at a discount (up to 90%). The catch: the provider can reclaim the machine with a 2-minute warning.
GOTCHA Spot instances are bad for databases or stateful web apps. If you don't build auto-draining mechanisms, you'll lose active data on termination.
HOW SPOT PREEMPTIONS FLOW
01 Request user requests 10 Spot instances for batch job tasks.
02 Allocation cloud provider assigns idle VM nodes at discounted pricing.
03 Reclaim warning cloud needs capacity back, sending a 2-minute metadata warning to VM.
04 Eviction resilient workload drains current transactions and exits before VM terminates.
POKE IT YOURSELF
curl -H 'Metadata: true' http://169.254.169.254/latest/meta-data/spot/termination-time — poll AWS metadata endpoint for termination alerts
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