# PlacementConstraint
<a name="API_PlacementConstraint"></a>

An object representing a constraint on task placement. For more information, see [Task placement constraints](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-placement-constraints.html) in the *Amazon Elastic Container Service Developer Guide*.

**Note**  
If you're using the Fargate launch type, task placement constraints aren't supported.

## Contents
<a name="API_PlacementConstraint_Contents"></a>

 ** expression **   <a name="ECS-Type-PlacementConstraint-expression"></a>
A cluster query language expression to apply to the constraint. The expression can have a maximum length of 2000 characters. You can't specify an expression if the constraint type is `distinctInstance`. For more information, see [Cluster query language](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cluster-query-language.html) in the *Amazon Elastic Container Service Developer Guide*.  
Type: String  
Required: No

 ** type **   <a name="ECS-Type-PlacementConstraint-type"></a>
The type of constraint. Use `distinctInstance` to ensure that each task in a particular group is running on a different container instance. Use `memberOf` to restrict the selection to a group of valid candidates.  
Type: String  
Valid Values: `distinctInstance | memberOf`   
Required: No

## See Also
<a name="API_PlacementConstraint_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/ecs-2014-11-13/PlacementConstraint) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/ecs-2014-11-13/PlacementConstraint) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/ecs-2014-11-13/PlacementConstraint)