# ListClusters


Returns a list of existing clusters.

## Request Syntax


```
{
   "maxResults": number,
   "nextToken": "string"
}
```

## Request Parameters


For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

The request accepts the following data in JSON format.

 ** [maxResults](#API_ListClusters_RequestSyntax) **   <a name="ECS-ListClusters-request-maxResults"></a>
The maximum number of cluster results that `ListClusters` returned in paginated output. When this parameter is used, `ListClusters` only returns `maxResults` results in a single page along with a `nextToken` response element. The remaining results of the initial request can be seen by sending another `ListClusters` request with the returned `nextToken` value. This value can be between 1 and 100. If this parameter isn't used, then `ListClusters` returns up to 100 results and a `nextToken` value if applicable.  
Type: Integer  
Required: No

 ** [nextToken](#API_ListClusters_RequestSyntax) **   <a name="ECS-ListClusters-request-nextToken"></a>
The `nextToken` value returned from a `ListClusters` request indicating that more results are available to fulfill the request and further calls are needed. If `maxResults` was provided, it's possible the number of results to be fewer than `maxResults`.  
This token should be treated as an opaque identifier that is only used to retrieve the next items in a list and not for other programmatic purposes.
Type: String  
Required: No

## Response Syntax


```
{
   "clusterArns": [ "string" ],
   "nextToken": "string"
}
```

## Response Elements


If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [clusterArns](#API_ListClusters_ResponseSyntax) **   <a name="ECS-ListClusters-response-clusterArns"></a>
The list of full Amazon Resource Name (ARN) entries for each cluster that's associated with your account.  
Type: Array of strings

 ** [nextToken](#API_ListClusters_ResponseSyntax) **   <a name="ECS-ListClusters-response-nextToken"></a>
The `nextToken` value to include in a future `ListClusters` request. When the results of a `ListClusters` request exceed `maxResults`, this value can be used to retrieve the next page of results. This value is `null` when there are no more results to return.  
Type: String

## Errors


For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** ClientException **   
These errors are usually caused by a client action. This client action might be using an action or resource on behalf of a user that doesn't have permissions to use the action or resource. Or, it might be specifying an identifier that isn't valid.    
 ** message **   
 Message that describes the cause of the exception.
HTTP Status Code: 400

 ** InvalidParameterException **   
The specified parameter isn't valid. Review the available parameters for the API request.  
For more information about service event errors, see [Amazon ECS service event messages](https://docs.amazonaws.cn/AmazonECS/latest/developerguide/service-event-messages-list.html).     
 ** message **   
 Message that describes the cause of the exception.
HTTP Status Code: 400

 ** ServerException **   
These errors are usually caused by a server issue.    
 ** message **   
 Message that describes the cause of the exception.
HTTP Status Code: 500

## Examples


In the following example or examples, the Authorization header contents (`AUTHPARAMS`) must be replaced with an Amazon Signature Version 4 signature. For more information, see [Signature Version 4 Signing Process](https://docs.amazonaws.cn/general/latest/gr/signature-version-4.html) in the * Amazon General Reference*.

You only need to learn how to sign HTTP requests if you intend to create them manually. When you use the [Amazon Command Line Interface](http://www.amazonaws.cn/cli/) or one of the [Amazon SDKs](http://www.amazonaws.cn/tools/) to make requests to Amazon, these tools automatically sign the requests for you, with the access key that you specify when you configure the tools. When you use these tools, you don't have to sign requests yourself.

### Example


This example request lists the clusters for your account.

#### Sample Request


```
POST / HTTP/1.1
Host: ecs.us-east-1.amazonaws.com
Accept-Encoding: identity
Content-Length: 2
X-Amz-Target: AmazonEC2ContainerServiceV20141113.ListClusters
X-Amz-Date: 20150429T170621Z
Content-Type: application/x-amz-json-1.1
Authorization: AUTHPARAMS

{}
```

#### Sample Response


```
HTTP/1.1 200 OK
Server: Server
Date: Wed, 29 Apr 2015 17:06:21 GMT
Content-Type: application/x-amz-json-1.1
Content-Length: 126
Connection: keep-alive
x-amzn-RequestId: 123a4b56-7c89-01d2-3ef4-example5678f

{
  "clusterArns": [
    "arn:aws:ecs:us-east-1:012345678910:cluster/My-cluster",
    "arn:aws:ecs:us-east-1:012345678910:cluster/default"
  ]
}
```

## See Also


For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon Command Line Interface V2](https://docs.amazonaws.cn/goto/cli2/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for .NET V4](https://docs.amazonaws.cn/goto/DotNetSDKV4/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for Go v2](https://docs.amazonaws.cn/goto/SdkForGoV2/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for JavaScript V3](https://docs.amazonaws.cn/goto/SdkForJavaScriptV3/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for Kotlin](https://docs.amazonaws.cn/goto/SdkForKotlin/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for PHP V3](https://docs.amazonaws.cn/goto/SdkForPHPV3/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for Python](https://docs.amazonaws.cn/goto/boto3/ecs-2014-11-13/ListClusters) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/ecs-2014-11-13/ListClusters)