---
title: "GET /#Action=PutWarmPool"
method: GET
path: "/#Action=PutWarmPool"
---

# GET /#Action=PutWarmPool

`GET /#Action=PutWarmPool`

Creates or updates a warm pool for the specified Auto Scaling group. A warm pool is a pool of pre-initialized EC2 instances that sits alongside the Auto Scaling group. Whenever your application needs to scale out, the Auto Scaling group can draw on the warm pool to meet its new desired capacity. For more information and example configurations, see [Warm pools for Amazon EC2 Auto Scaling](https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-warm-pools.html) in the _Amazon EC2 Auto Scaling User Guide_.

This operation must be called from the Region in which the Auto Scaling group was created. This operation cannot be called on an Auto Scaling group that has a mixed instances policy or a launch template or launch configuration that requests Spot Instances.

You can view the instances in the warm pool using the DescribeWarmPool API call. If you are no longer using a warm pool, you can delete it by calling the DeleteWarmPool API.

## Query parameters

- `AutoScalingGroupName` string, required
- `MaxGroupPreparedCapacity` integer
- `MinSize` integer
- `PoolState` 'Stopped' | 'Running' | 'Hibernated'
- `InstanceReusePolicy` object — <p>Describes an instance reuse policy for a warm pool. </p> <p>For more information, see <a href="https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-warm-pools.html">Warm pools for Amazon EC2 Auto Scaling</a> in the <i>Amazon EC2 Auto Scaling User Guide</i>.</p>
  - `ReuseOnScaleIn` boolean — Specifies whether instances in the Auto Scaling group can be returned to the warm pool on scale in.
- `Action` 'PutWarmPool', required
- `Version` '2011-01-01', required

## Response `200`

Success

## Other responses

- `480` — LimitExceededFault
- `481` — ResourceContentionFault

---

[API](https://skmtc.net/aws/apis/autoscaling.md) · [All operations](https://skmtc.net/aws/apis/autoscaling/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/aws/autoscaling/versions/5e07057bfecf/schema)