# UpdateHostKey
<a name="API_UpdateHostKey"></a>

Updates the host key that's specified by the `ServerId` and `HostKeyId` parameters. You can update the description of the host key, change where the host key is stored by specifying the `StorageType`, and specify the AWS KMS key used to encrypt the host key when it's stored in AWS Secrets Manager.

To change a host key's storage type from `SERVICE_MANAGED` to `SECRETS_MANAGER`, you must have the `transfer:ExportHostKey` permission. `transfer:ExportHostKey` is a permission-only action that has no corresponding API operation.

## Request Syntax
<a name="API_UpdateHostKey_RequestSyntax"></a>

```
{
   "Description": "{{string}}",
   "HostKeyId": "{{string}}",
   "KmsKey": "{{string}}",
   "ServerId": "{{string}}",
   "StorageType": "{{string}}"
}
```

## Request Parameters
<a name="API_UpdateHostKey_RequestParameters"></a>

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.

 ** [Description](#API_UpdateHostKey_RequestSyntax) **   <a name="TransferFamily-UpdateHostKey-request-Description"></a>
An updated description for the host key.  
Type: String  
Length Constraints: Minimum length of 0. Maximum length of 200.  
Pattern: `[\p{Print}]*`   
Required: No

 ** [HostKeyId](#API_UpdateHostKey_RequestSyntax) **   <a name="TransferFamily-UpdateHostKey-request-HostKeyId"></a>
The identifier of the host key that you are updating.  
Type: String  
Length Constraints: Fixed length of 25.  
Pattern: `hostkey-[0-9a-f]{17}`   
Required: Yes

 ** [KmsKey](#API_UpdateHostKey_RequestSyntax) **   <a name="TransferFamily-UpdateHostKey-request-KmsKey"></a>
The Amazon Resource Name (ARN) of the AWS KMS key used to encrypt the AWS Secrets Manager secret that stores the host key. If you specify a customer managed key, its key policy must allow the `AWSServiceRoleForTransfer` service-linked role to decrypt the secret. If you don't specify a value, AWS Transfer Family uses the AWS managed key for AWS Secrets Manager.  
Type: String  
Length Constraints: Minimum length of 20. Maximum length of 1600.  
Pattern: `arn:\S+`   
Required: No

 ** [ServerId](#API_UpdateHostKey_RequestSyntax) **   <a name="TransferFamily-UpdateHostKey-request-ServerId"></a>
The identifier of the server that contains the host key that you are updating.  
Type: String  
Length Constraints: Fixed length of 19.  
Pattern: `s-([0-9a-f]{17})`   
Required: Yes

 ** [StorageType](#API_UpdateHostKey_RequestSyntax) **   <a name="TransferFamily-UpdateHostKey-request-StorageType"></a>
Specifies whether the host key is stored by AWS Transfer Family (`SERVICE_MANAGED`) or in AWS Secrets Manager (`SECRETS_MANAGER`). When you specify `SECRETS_MANAGER`, AWS Transfer Family stores the private host key material in an AWS Secrets Manager secret.  
Type: String  
Valid Values: `SERVICE_MANAGED | SECRETS_MANAGER`   
Required: No

## Response Syntax
<a name="API_UpdateHostKey_ResponseSyntax"></a>

```
{
   "HostKeyId": "string",
   "ServerId": "string"
}
```

## Response Elements
<a name="API_UpdateHostKey_ResponseElements"></a>

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

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

 ** [HostKeyId](#API_UpdateHostKey_ResponseSyntax) **   <a name="TransferFamily-UpdateHostKey-response-HostKeyId"></a>
Returns the host key identifier for the updated host key.  
Type: String  
Length Constraints: Fixed length of 25.  
Pattern: `hostkey-[0-9a-f]{17}` 

 ** [ServerId](#API_UpdateHostKey_ResponseSyntax) **   <a name="TransferFamily-UpdateHostKey-response-ServerId"></a>
Returns the server identifier for the server that contains the updated host key.  
Type: String  
Length Constraints: Fixed length of 19.  
Pattern: `s-([0-9a-f]{17})` 

## Errors
<a name="API_UpdateHostKey_Errors"></a>

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

 ** InternalServiceError **   
This exception is thrown when an error occurs in the AWS Transfer Family service.  
HTTP Status Code: 500

 ** InvalidRequestException **   
This exception is thrown when the client submits a malformed request.  
HTTP Status Code: 400

 ** ResourceNotFoundException **   
This exception is thrown when a resource is not found by the AWSTransfer Family service.  
HTTP Status Code: 400

 ** ServiceUnavailableException **   
The request has failed because the AWSTransfer Family service is not available.  
HTTP Status Code: 500

 ** ThrottlingException **   
The request was denied due to request throttling.  
HTTP Status Code: 400

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

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for C\+\+](https://docs.aws.amazon.com/goto/SdkForCpp/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for Python (Boto3)](https://docs.aws.amazon.com/goto/boto3/transfer-2018-11-05/UpdateHostKey) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/transfer-2018-11-05/UpdateHostKey)