Directory Buckets (S3 Express One Zone)

Create S3 Express One Zone directory buckets for single-digit millisecond latency workloads.

S3 Express One Zone directory buckets deliver consistent single-digit millisecond request latency by storing data in a specific Availability Zone. They are optimised for high-throughput workloads such as machine learning training, financial analytics, and media processing.

Create a directory bucket

Set is_directory_bucket = true and supply the required Availability Zone ID:

module "s3_directory_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"

  bucket               = "my-express-bucket"
  is_directory_bucket  = true
  availability_zone_id = "use1-az4"
  data_redundancy      = "SingleAvailabilityZone"
  type                 = "Directory"
  location_type        = "AvailabilityZone"
}

Bucket naming

Directory bucket names follow a strict convention imposed by AWS. The module automatically builds the name:

${var.bucket}--${var.availability_zone_id}--x-s3

For the example above the resulting bucket name would be my-express-bucket--use1-az4--x-s3.

Required variables

Variable	Description	Example value
is_directory_bucket	Enable directory bucket mode	true
availability_zone_id	Availability Zone or Local Zone ID	"use1-az4"
data_redundancy	Redundancy model	"SingleAvailabilityZone"
type	Bucket type	"Directory"
location_type	Location type	"AvailabilityZone" or "LocalZone"

Encryption

Directory buckets support server-side encryption:

module "s3_directory_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"

  bucket               = "my-express-bucket"
  is_directory_bucket  = true
  availability_zone_id = "use1-az4"
  data_redundancy      = "SingleAvailabilityZone"
  type                 = "Directory"
  location_type        = "AvailabilityZone"

  server_side_encryption_configuration = {
    rule = {
      apply_server_side_encryption_by_default = {
        sse_algorithm = "AES256"
      }
    }
  }
}

Output values

Output	Description
s3_directory_bucket_name	The full bucket name including the AZ suffix
s3_directory_bucket_arn	The ARN of the directory bucket

output "directory_bucket_name" {
  value = module.s3_directory_bucket.s3_directory_bucket_name
}

output "directory_bucket_arn" {
  value = module.s3_directory_bucket.s3_directory_bucket_arn
}

Feature availability

Directory buckets do not support all standard S3 features. The module enforces these restrictions automatically by checking var.is_directory_bucket:

The following features are not available for directory buckets:

Feature	Available
Versioning	No
ACLs	No
Static website hosting	No
Server access logging	No
Replication	No
Object Lock	No
Intelligent-Tiering	No
Transfer Acceleration	No
Request payment	No
CORS	No
Public access block	No
Lifecycle rules	Yes (limited)
Server-side encryption	Yes
Bucket policy	Yes

Lifecycle rules on directory buckets

Directory buckets support a subset of lifecycle rules. Use lifecycle_rule as normal — the module routes the configuration to the correct resource (aws_s3_bucket_lifecycle_configuration) for both standard and directory bucket types.