(aws-efs): support one-zone FileSystem

[rectalogic]

EFS FileSystem should support one-zone storage class
https://aws.amazon.com/blogs/storage/lower-your-amazon-efs-costs-by-47-with-one-zone-storage-classes/

This is done by setting the AWS::EFS::FileSystem AvailabilityZoneName
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-efs-filesystem.html#cfn-efs-filesystem-availabilityzonename

Use Case

It's cheaper

Proposed Solution

Expose oneZone property and have that set AvailabilityZoneName to one of the subnet availabilityZones for the subnets the FileSystem is in?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[jumic]

It is already possible to deploy a one zone EFS using escape hatches, e.g.:

const fileSystem = new efs.FileSystem(this, 'MyFileSystem', {
  vpc,
  vpcSubnets: {
    availabilityZones: [vpc.availabilityZones[0]],
    onePerAz: true,
  }
});
(fileSystem.node.defaultChild as efs.CfnFileSystem).availabilityZoneName = vpc.availabilityZones[0];

vpcSubnets has to be specified explicitly and has to be restricted to the AZ, otherwise it will create a mount target in each AZ which will fail.

@ AWS CDK Team: If you would like to get a community contribution for this feature request:
Could you please specify how interface FileSystemProps should be extended?

• Property oneZone (boolean) and property availabilityZoneName? availabilityZoneName can be only specified if oneZone is set to true. If availabilityZoneName is not specified, it will create the file system in the first AZ of the VPC.
• Single property availabilityZoneName? (similar to CloudFormation)

[harrytalbot]

I've just come across the same issue, and while it's frustrating to have to do One-Zone seems to work if you switch to the level 1 construct CfnFileSystem:

CfnFileSystem(this, efsID, CfnFileSystemProps.builder().availabilityZoneName("eu-west-1a").build())

Of course now the rest of the resources in my stack are being changed to lvl1 constructs...

[filod]

still an issue

[github-actions]

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