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Amazon Elastic File System Construct Library

See: Description

Package Description

Amazon Elastic File System Construct Library


cfn-resources: Stable

cdk-constructs: Stable

Amazon Elastic File System (Amazon EFS) provides a simple, scalable, fully managed elastic NFS file system for use with AWS Cloud services and on-premises resources. Amazon EFS provides file storage in the AWS Cloud. With Amazon EFS, you can create a file system, mount the file system on an Amazon EC2 instance, and then read and write data to and from your file system.

This module is part of the AWS Cloud Development Kit project.

File Systems

Amazon EFS provides elastic, shared file storage that is POSIX-compliant. The file system you create supports concurrent read and write access from multiple Amazon EC2 instances and is accessible from all of the Availability Zones in the AWS Region where it is created. Learn more about EFS file systems

Create an Amazon EFS file system

A Virtual Private Cloud (VPC) is required to create an Amazon EFS file system. The following example creates a file system that is encrypted at rest, running in General Purpose performance mode, and Bursting throughput mode and does not transition files to the Infrequent Access (IA) storage class.

 // Example automatically generated. See
 Object fileSystem = FileSystem.Builder.create(this, "MyEfsFileSystem")
         .vpc(new Vpc(this, "VPC"))
         .lifecyclePolicy(efs.LifecyclePolicy.getAFTER_14_DAYS())// files are not transitioned to infrequent access (IA) storage by default

⚠️ An Amazon EFS file system's performance mode can't be changed after the file system has been created. Updating this property will replace the file system.

Any file system that has been created outside the stack can be imported into your CDK app.

Use the fromFileSystemAttributes() API to import an existing file system. Here is an example of giving a role write permissions on a file system.

 // Example automatically generated. See
 IFileSystem importedFileSystem = efs.FileSystem.fromFileSystemAttributes(this, "existingFS", new FileSystemAttributes()
         .fileSystemId("fs-12345678")// You can also use fileSystemArn instead of fileSystemId.
         .securityGroup(ec2.SecurityGroup.fromSecurityGroupId(this, "SG", "sg-123456789", new SecurityGroupImportOptions()


If you need to grant file system permissions to another resource, you can use the .grant() API. As an example, the following code gives elasticfilesystem:ClientWrite permissions to an IAM role.

 // Example automatically generated without compilation. See
 Object role = Role.Builder.create(this, "Role")
         .assumedBy(new AnyPrincipal())
 fileSystem.grant(role, "elasticfilesystem:ClientWrite");

Access Point

An access point is an application-specific view into an EFS file system that applies an operating system user and group, and a file system path, to any file system request made through the access point. The operating system user and group override any identity information provided by the NFS client. The file system path is exposed as the access point's root directory. Applications using the access point can only access data in its own directory and below. To learn more, see Mounting a File System Using EFS Access Points.

Use the addAccessPoint API to create an access point from a fileSystem.

 // Example automatically generated. See

By default, when you create an access point, the root(/) directory is exposed to the client connecting to the access point. You can specify a custom path with the path property.

If path does not exist, it will be created with the settings defined in the creationInfo. See Creating Access Points for more details.

Any access point that has been created outside the stack can be imported into your CDK app.

Use the fromAccessPointAttributes() API to import an existing access point.

 // Example automatically generated. See
 efs.AccessPoint.fromAccessPointAttributes(this, "ap", Map.of(
         "accessPointId", "fsap-1293c4d9832fo0912",
         "fileSystem", efs.FileSystem.fromFileSystemAttributes(this, "efs", Map.of(
                 "fileSystemId", "fs-099d3e2f",
                 "securityGroup", ec2.SecurityGroup.fromSecurityGroupId(this, "sg", "sg-51530134")))));

⚠️ Notice: When importing an Access Point using fromAccessPointAttributes(), you must make sure the mount targets are deployed and their lifecycle state is available. Otherwise, you may encounter the following error when deploying:

EFS file system referenced by access point has mount targets created in all availability zones the function will execute in, but not all are in the available life cycle state yet. Please wait for them to become available and try the request again.


To control who can access the EFS, use the .connections attribute. EFS has a fixed default port, so you don't need to specify the port:

 // Example automatically generated. See

Learn more about managing file system network accessibility

Mounting the file system using User Data

After you create a file system, you can create mount targets. Then you can mount the file system on EC2 instances, containers, and Lambda functions in your virtual private cloud (VPC).

The following example automatically mounts a file system during instance launch.

 // Example automatically generated. See
 instance.userData.addCommands("yum check-update -y", "yum upgrade -y", "yum install -y amazon-efs-utils", "yum install -y nfs-utils", "file_system_id_1=" + fileSystem.getFileSystemId(), "efs_mount_point_1=/mnt/efs/fs1", "mkdir -p \"${efs_mount_point_1}\"", "test -f \"/sbin/mount.efs\" && echo \"${file_system_id_1}:/ ${efs_mount_point_1} efs defaults,_netdev\" >> /etc/fstab || " + "echo \"${file_system_id_1}.efs." + Stack.of(this).getRegion() + " ${efs_mount_point_1} nfs4 nfsvers=4.1,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport,_netdev 0 0\" >> /etc/fstab", "mount -a -t efs,nfs4 defaults");

Learn more about mounting EFS file systems


Since file systems are stateful resources, by default the file system will not be deleted when your stack is deleted.

You can configure the file system to be destroyed on stack deletion by setting a removalPolicy

 // Example automatically generated. See
 Object fileSystem = FileSystem.Builder.create(this, "EfsFileSystem")
         .vpc(new Vpc(this, "VPC"))
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