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Amazon Elastic File System
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CreateMountTarget

Creates a mount target for a file system. You can then mount the file system on EC2 instances via the mount target.

You can create one mount target in each Availability Zone in your VPC. All EC2 instances in a VPC within a given Availability Zone share a single mount target for a given file system. If you have multiple subnets in an Availability Zone, you create a mount target in one of the subnets. EC2 instances do not need to be in the same subnet as the mount target in order to access their file system. For more information, see Amazon EFS: How it Works.

In the request, you also specify a file system ID for which you are creating the mount target and the file system's lifecycle state must be available. For more information, see DescribeFileSystems.

In the request, you also provide a subnet ID, which determines the following:

  • VPC in which Amazon EFS creates the mount target

  • Availability Zone in which Amazon EFS creates the mount target

  • IP address range from which Amazon EFS selects the IP address of the mount target (if you don't specify an IP address in the request)

After creating the mount target, Amazon EFS returns a response that includes, a MountTargetId and an IpAddress. You use this IP address when mounting the file system in an EC2 instance. You can also use the mount target's DNS name when mounting the file system. The EC2 instance on which you mount the file system via the mount target can resolve the mount target's DNS name to its IP address. For more information, see How it Works: Implementation Overview.

Note that you can create mount targets for a file system in only one VPC, and there can be only one mount target per Availability Zone. That is, if the file system already has one or more mount targets created for it, the subnet specified in the request to add another mount target must meet the following requirements:

  • Must belong to the same VPC as the subnets of the existing mount targets

  • Must not be in the same Availability Zone as any of the subnets of the existing mount targets

If the request satisfies the requirements, Amazon EFS does the following:

  • Creates a new mount target in the specified subnet.

  • Also creates a new network interface in the subnet as follows:

    • If the request provides an IpAddress, Amazon EFS assigns that IP address to the network interface. Otherwise, Amazon EFS assigns a free address in the subnet (in the same way that the Amazon EC2 CreateNetworkInterface call does when a request does not specify a primary private IP address).

    • If the request provides SecurityGroups, this network interface is associated with those security groups. Otherwise, it belongs to the default security group for the subnet's VPC.

    • Assigns the description Mount target fsmt-id for file system fs-id where fsmt-id is the mount target ID, and fs-id is the FileSystemId.

    • Sets the requesterManaged property of the network interface to true, and the requesterId value to EFS.

    Each Amazon EFS mount target has one corresponding requester-managed EC2 network interface. After the network interface is created, Amazon EFS sets the NetworkInterfaceId field in the mount target's description to the network interface ID, and the IpAddress field to its address. If network interface creation fails, the entire CreateMountTarget operation fails.

Note

The CreateMountTarget call returns only after creating the network interface, but while the mount target state is still creating, you can check the mount target creation status by calling the DescribeMountTargets operation, which among other things returns the mount target state.

We recommend you create a mount target in each of the Availability Zones. There are cost considerations for using a file system in an Availability Zone through a mount target created in another Availability Zone. For more information, see Amazon EFS. In addition, by always using a mount target local to the instance's Availability Zone, you eliminate a partial failure scenario. If the Availability Zone in which your mount target is created goes down, then you won't be able to access your file system through that mount target.

This operation requires permissions for the following action on the file system:

  • elasticfilesystem:CreateMountTarget

This operation also requires permissions for the following Amazon EC2 actions:

  • ec2:DescribeSubnets

  • ec2:DescribeNetworkInterfaces

  • ec2:CreateNetworkInterface

Request Syntax

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POST /2015-02-01/mount-targets HTTP/1.1 Content-type: application/json { "FileSystemId": "string", "IpAddress": "string", "SecurityGroups": [ "string" ], "SubnetId": "string" }

URI Request Parameters

The request does not use any URI parameters.

Request Body

The request accepts the following data in JSON format.

FileSystemId

ID of the file system for which to create the mount target.

Type: String

Required: Yes

IpAddress

Valid IPv4 address within the address range of the specified subnet.

Type: String

Required: No

SecurityGroups

Up to five VPC security group IDs, of the form sg-xxxxxxxx. These must be for the same VPC as subnet specified.

Type: Array of strings

Array Members: Maximum number of 5 items.

Required: No

SubnetId

ID of the subnet to add the mount target in.

Type: String

Required: Yes

Response Syntax

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HTTP/1.1 200 Content-type: application/json { "FileSystemId": "string", "IpAddress": "string", "LifeCycleState": "string", "MountTargetId": "string", "NetworkInterfaceId": "string", "OwnerId": "string", "SubnetId": "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.

FileSystemId

ID of the file system for which the mount target is intended.

Type: String

IpAddress

Address at which the file system may be mounted via the mount target.

Type: String

LifeCycleState

Lifecycle state of the mount target.

Type: String

Valid Values: creating | available | deleting | deleted

MountTargetId

System-assigned mount target ID.

Type: String

NetworkInterfaceId

ID of the network interface that Amazon EFS created when it created the mount target.

Type: String

OwnerId

AWS account ID that owns the resource.

Type: String

SubnetId

ID of the mount target's subnet.

Type: String

Errors

BadRequest

Returned if the request is malformed or contains an error such as an invalid parameter value or a missing required parameter.

HTTP Status Code: 400

FileSystemNotFound

Returned if the specified FileSystemId does not exist in the requester's AWS account.

HTTP Status Code: 404

IncorrectFileSystemLifeCycleState

Returned if the file system's life cycle state is not "created".

HTTP Status Code: 409

InternalServerError

Returned if an error occurred on the server side.

HTTP Status Code: 500

IpAddressInUse

Returned if the request specified an IpAddress that is already in use in the subnet.

HTTP Status Code: 409

MountTargetConflict

Returned if the mount target would violate one of the specified restrictions based on the file system's existing mount targets.

HTTP Status Code: 409

NetworkInterfaceLimitExceeded

The calling account has reached the ENI limit for the specific AWS region. Client should try to delete some ENIs or get its account limit raised. For more information, see Amazon VPC Limits in the Amazon Virtual Private Cloud User Guide (see the Network interfaces per VPC entry in the table).

HTTP Status Code: 409

NoFreeAddressesInSubnet

Returned if IpAddress was not specified in the request and there are no free IP addresses in the subnet.

HTTP Status Code: 409

SecurityGroupLimitExceeded

Returned if the size of SecurityGroups specified in the request is greater than five.

HTTP Status Code: 400

SecurityGroupNotFound

Returned if one of the specified security groups does not exist in the subnet's VPC.

HTTP Status Code: 400

SubnetNotFound

Returned if there is no subnet with ID SubnetId provided in the request.

HTTP Status Code: 400

UnsupportedAvailabilityZone

HTTP Status Code: 400

Examples

Example 1: Add a mount target to a file system

The following request creates a mount target for a file system. The request specifies values for only the required FileSystemId and SubnetId parameters. The request does not provide the optional IpAddress and SecurityGroups parameters. For IpAddress, the operation uses one of the available IP addresses in the specified subnet. And, the operation uses the default security group associated with the VPC for the SecurityGroups.

Sample Request

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POST /2015-02-01/mount-targets HTTP/1.1 Host: elasticfilesystem.us-west-2.amazonaws.com x-amz-date: 20140620T221118Z Authorization: <...> Content-Type: application/json Content-Length: 160 {"SubnetId": "subnet-748c5d03", "FileSystemId": "fs-e2a6438b"}

Sample Response

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HTTP/1.1 200 OK x-amzn-RequestId: c3616af3-33fa-40ad-ae0d-d3895a2c3a1f Content-Type: application/json Content-Length: 252 { "MountTargetId": "fsmt-55a4413c", "NetworkInterfaceId": "eni-d95852af", "FileSystemId": "fs-e2a6438b", "LifeCycleState": "available", "SubnetId": "subnet-748c5d03", "OwnerId": "231243201240", "IpAddress": "172.31.22.183" }

Example 2: Add a mount target to a file system

The following request specifies all the request parameters to create a mount target.

Sample Request

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POST /2015-02-01/mount-targets HTTP/1.1 Host: elasticfilesystem.us-west-2.amazonaws.com x-amz-date: 20140620T221118Z Authorization: <...> Content-Type: application/json Content-Length: 160 { "FileSystemId":"fs-47a2c22e", "SubnetId":"subnet-fd04ff94", "IpAddress":"10.0.2.42", "SecurityGroups":[ "sg-1a2b3c4d" ] }

Sample Response

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HTTP/1.1 200 OK x-amzn-RequestId: c3616af3-33fa-40ad-ae0d-d3895a2c3a1f Content-Type: application/json Content-Length: 252 { "OwnerId":"251839141158", "MountTargetId":"fsmt-9a13661e", "FileSystemId":"fs-47a2c22e", "SubnetId":"subnet-fd04ff94", "LifeCycleState":"available", "IpAddress":"10.0.2.42", "NetworkInterfaceId":"eni-1bcb7772" }

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: