Spot Instance Best Practices

Your instance type requirements, budget requirements, and application design will determine how to apply the following best practices for your application:

• Be flexible about instance types. A Spot Instance pool is a set of unused EC2 instances with the same instance type (for example, m5.large) and Availability Zone (for example, us-east-1a). You should be flexible about which instance types you request and in which Availability Zones you can deploy your workload. This gives Spot a better chance to find and allocate your required amount of compute capacity. For example, don't just ask for c5.large if you'd be willing to use larges from the c4, m5, and m4 families.

• Use the price and capacity optimized allocation strategy. Allocation strategies in EC2 Auto Scaling groups help you to provision your target capacity without the need to manually look for the Spot Instance pools with spare capacity. We recommend using the price-capacity-optimized strategy because this strategy automatically provisions instances from the most-available Spot Instance pools that also have the lowest possible price. Because your Spot Instance capacity is sourced from pools with optimal capacity, this decreases the possibility that your Spot Instances are interrupted. For more information about allocation strategies, see Spot Instances in the Amazon EC2 Auto Scaling User Guide.

• Use proactive capacity rebalancing. Capacity Rebalancing helps you maintain workload availability by proactively augmenting your Auto Scaling group with a new Spot Instance before a running Spot Instance receives the two-minute interruption notice. When Capacity Rebalancing is enabled, Auto Scaling attempts to proactively replace Spot Instances that have received a rebalance recommendation, providing the opportunity to rebalance your workload to new Spot Instances that are not at elevated risk of interruption.

• Use integrated AWS services to manage your Spot Instances. Other AWS services integrate with Spot to reduce overall compute costs without the need to manage the individual instances or fleets. We recommend that you consider the following solutions for your applicable workloads: Amazon EMR, Amazon ECS, AWS Batch, Amazon EKS, SageMaker, AWS Elastic Beanstalk, and Amazon GameLift. To learn more about Spot best practices with these services, see the Amazon EC2 Spot Instances Workshops Website.

• Choose the modern and correct launch tool for Spot Instances. If one of the AWS integrated services is not a good fit for your workload, and you still need to build your application with control over the launch of Spot Instances, use the right tool. For most workloads, you should use EC2 Auto Scaling because it supplies a more comprehensive feature set for a wide variety of workloads, like ELB-backed applications, containerized workloads, and queue processing jobs. If you need more control over individual requests and are looking for a “launch only” tool, use EC2 Fleet in instant mode as a drop-in replacement to RunInstances, but with a wider set of capabilities, such as instance type diversification and allocation strategies. For more information, see Which is the best Spot request method to use? in the Amazon EC2 User Guide.