AWS Volumes Configuration

The AWS volumes customization allows the user to specify configuration for both root and non-root storage volumes for AWS machines. The volumes customization can be applied to both control plane and worker machines. This customization will be available when the provider-specific cluster configuration patch is included in the ClusterClass.

Configuration Options

The volumes configuration supports two types of volumes:

Root Volume: The primary storage volume for the instance (typically /dev/sda1)
Non-Root Volumes: Additional storage volumes that can be attached to the instance

Volume Configuration Fields

Each volume can be configured with the following fields:

Field	Type	Required	Description	Default
`deviceName`	string	No	Device name for the volume (e.g., `/dev/sda1`, `/dev/sdf`)	-
`size`	int64	No	Size in GiB (minimum 8)	Based on AMI, usually 20GiB
`type`	string	No	EBS volume type (`gp2`, `gp3`, `io1`, `io2`)	-
`iops`	int64	No	IOPS for provisioned volumes (io1, io2, gp3)	-
`throughput`	int64	No	Throughput in MiB/s (gp3 only)	-
`encrypted`	bool	No	Whether the volume should be encrypted	false
`encryptionKey`	string	No	KMS key ID or ARN for encryption	AWS default key

Supported Volume Types

gp2: General Purpose SSD (up to 16,000 IOPS)
gp3: General Purpose SSD with configurable IOPS and throughput
io1: Provisioned IOPS SSD (up to 64,000 IOPS)
io2: Provisioned IOPS SSD with higher durability (up to 64,000 IOPS)

Examples

Root Volume Only

To specify only a root volume configuration:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: <NAME>
spec:
  topology:
    variables:
      - name: clusterConfig
        value:
          controlPlane:
            aws:
              volumes:
                root:
                  deviceName: "/dev/sda1"
                  size: 100
                  type: "gp3"
                  iops: 3000
                  throughput: 125
                  encrypted: true
                  encryptionKey: "arn:aws:kms:us-west-2:123456789012:key/12345678-1234-1234-1234-123456789012"
      - name: workerConfig
        value:
          aws:
            volumes:
              root:
                size: 200
                type: "gp3"
                iops: 4000
                throughput: 250
                encrypted: true

Non-Root Volumes Only

To specify only additional non-root volumes:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: <NAME>
spec:
  topology:
    variables:
      - name: clusterConfig
        value:
          controlPlane:
            aws:
              volumes:
                nonroot:
                  - deviceName: "/dev/sdf"
                    size: 500
                    type: "gp3"
                    iops: 4000
                    throughput: 250
                    encrypted: true
                  - deviceName: "/dev/sdg"
                    size: 1000
                    type: "gp2"
                    encrypted: false
      - name: workerConfig
        value:
          aws:
            volumes:
              nonroot:
                - deviceName: "/dev/sdf"
                  size: 200
                  type: "io1"
                  iops: 10000
                  encrypted: true

Both Root and Non-Root Volumes

To specify both root and non-root volumes:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: <NAME>
spec:
  topology:
    variables:
      - name: clusterConfig
        value:
          controlPlane:
            aws:
              volumes:
                root:
                  size: 100
                  type: "gp3"
                  iops: 3000
                  throughput: 125
                  encrypted: true
                nonroot:
                  - deviceName: "/dev/sdf"
                    size: 500
                    type: "gp3"
                    iops: 4000
                    throughput: 250
                    encrypted: true
                  - deviceName: "/dev/sdg"
                    size: 1000
                    type: "gp2"
                    encrypted: false
      - name: workerConfig
        value:
          aws:
            volumes:
              root:
                size: 200
                type: "gp3"
                iops: 4000
                throughput: 250
                encrypted: true
              nonroot:
                - deviceName: "/dev/sdf"
                  size: 100
                  type: "io1"
                  iops: 10000
                  encrypted: true

MachineDeployment Overrides

You can customize individual MachineDeployments by using the overrides field:

spec:
  topology:
    # ...
    workers:
      machineDeployments:
        - class: default-worker
          name: md-0
          variables:
            overrides:
              - name: workerConfig
                value:
                  aws:
                    volumes:
                      root:
                        size: 500
                        type: "gp3"
                        iops: 10000
                        throughput: 500
                        encrypted: true
                      nonroot:
                        - deviceName: "/dev/sdf"
                          size: 1000
                          type: "io2"
                          iops: 20000
                          encrypted: true

Resulting CAPA Configuration

Applying the volumes configuration will result in the following values being set in the AWSMachineTemplate:

Root Volume Configuration

When a root volume is specified, it will be set in the rootVolume field:

spec:
  template:
    spec:
      rootVolume:
        deviceName: "/dev/sda1"
        size: 100
        type: "gp3"
        iops: 3000
        throughput: 125
        encrypted: true
        encryptionKey: "arn:aws:kms:us-west-2:123456789012:key/12345678-1234-1234-1234-123456789012"

Non-Root Volumes Configuration

When non-root volumes are specified, they will be set in the nonRootVolumes field:

spec:
  template:
    spec:
      nonRootVolumes:
        - deviceName: "/dev/sdf"
          size: 500
          type: "gp3"
          iops: 4000
          throughput: 250
          encrypted: true
        - deviceName: "/dev/sdg"
          size: 1000
          type: "gp2"
          encrypted: false

EKS Configuration

For EKS clusters, the volumes configuration follows the same structure but is specified under the EKS worker configuration:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: <NAME>
spec:
  topology:
    variables:
      - name: workerConfig
        value:
          eks:
            volumes:
              root:
                size: 200
                type: "gp3"
                iops: 4000
                throughput: 250
                encrypted: true
              nonroot:
                - deviceName: "/dev/sdf"
                  size: 500
                  type: "gp3"
                  iops: 4000
                  throughput: 250
                  encrypted: true

Best Practices

Root Volume: Always specify a root volume for consistent boot disk configuration
Encryption: Enable encryption for sensitive workloads using either AWS default keys or customer-managed KMS keys
IOPS and Throughput: Use gp3 volumes for better price/performance ratio with configurable IOPS and throughput
Device Names: Use standard device naming conventions (/dev/sda1 for root, /dev/sdf onwards for additional volumes)
Size Planning: Consider future growth when sizing volumes, as resizing EBS volumes requires downtime
Volume Types: Choose appropriate volume types based on workload requirements:
- gp2/gp3: General purpose workloads
- io1/io2: High-performance database workloads requiring consistent IOPS

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Last modified October 7, 2025: release(main): v0.35.1 (#1343) (e059bb5)