This is the new *CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [AWS CloudFormation User Guide](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/Welcome.html).

# AWS::ECS::Service PlacementStrategy
<a name="aws-properties-ecs-service-placementstrategy"></a>

The task placement strategy for a task or service. For more information, see [Task placement strategies](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-placement-strategies.html) in the *Amazon Elastic Container Service Developer Guide*.

## Syntax
<a name="aws-properties-ecs-service-placementstrategy-syntax"></a>

To declare this entity in your CloudFormation template, use the following syntax:

### JSON
<a name="aws-properties-ecs-service-placementstrategy-syntax.json"></a>

```
{
  "[Field](#cfn-ecs-service-placementstrategy-field)" : {{String}},
  "[Type](#cfn-ecs-service-placementstrategy-type)" : {{String}}
}
```

### YAML
<a name="aws-properties-ecs-service-placementstrategy-syntax.yaml"></a>

```
  [Field](#cfn-ecs-service-placementstrategy-field): {{String}}
  [Type](#cfn-ecs-service-placementstrategy-type): {{String}}
```

## Properties
<a name="aws-properties-ecs-service-placementstrategy-properties"></a>

`Field`  <a name="cfn-ecs-service-placementstrategy-field"></a>
The field to apply the placement strategy against. For the `spread` placement strategy, valid values are `instanceId` (or `host`, which has the same effect), or any platform or custom attribute that's applied to a container instance, such as `attribute:ecs.availability-zone`. For the `binpack` placement strategy, valid values are `cpu` and `memory`. For the `random` placement strategy, this field is not used.  
*Required*: No  
*Type*: String  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Type`  <a name="cfn-ecs-service-placementstrategy-type"></a>
The type of placement strategy. The `random` placement strategy randomly places tasks on available candidates. The `spread` placement strategy spreads placement across available candidates evenly based on the `field` parameter. The `binpack` strategy places tasks on available candidates that have the least available amount of the resource that's specified with the `field` parameter. For example, if you binpack on memory, a task is placed on the instance with the least amount of remaining memory but still enough to run the task.  
*Required*: Yes  
*Type*: String  
*Allowed values*: `binpack | random | spread`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## See also
<a name="aws-properties-ecs-service-placementstrategy--seealso"></a>
+  [Associate an Application Load Balancer with a service](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ecs-service.html#aws-resource-ecs-service--examples--Associate_an_Application_Load_Balancer_with_a_service)