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Version: v1.4 (latest)

Image Security

Available as of v1.4.0

Harvester v1.4.0 and later versions allow you to encrypt and decrypt virtual machine images. The encryption mechanism utilizes the Linux kernel module dm_crypt and the command-line utility cryptsetup.

Prerequisites​

Prepare the following resources:

  • Source virtual machine image: You can upload or create an image using any of the supported methods.

    caution

    Do not upload an encrypted image.

  • Secret: A Kubernetes secret is used as the passphrase of dm_crypt. You must specify the value of the CRYPTO_KEY_VALUE field. All other fields are fixed.

    Example of a secret:

    apiVersion: v1
    kind: Secret
    metadata:
      name: encryption
      namespace: default
    data:
      CRYPTO_KEY_CIPHER: aes-xts-plain64
      CRYPTO_KEY_HASH: sha256
      CRYPTO_KEY_PROVIDER: secret
      CRYPTO_KEY_SIZE: 256
      CRYPTO_KEY_VALUE: "Your encryption passphrase"
      CRYPTO_PBKDF: argon2i
    important

    The example contains the default YAML code for Kubernetes secrets. Aside from this, you can use encryption options for LUKS mode, which is a cryptsetup operating mode. Harvester v1.4.1 and later versions support these options, but you must verify that these are supported by your nodes.

    OptionPossible Values
    CRYPTO_KEY_CIPHERaes-xts-plain, aes-xts-plain64, aes-cbc-plain, aes-cbc-plain64, aes-cbc-essiv:sha256
    CRYPTO_KEY_HASHsha256, sha384, sha512
    CRYPTO_KEY_SIZE256, 384, 512
    CRYPTO_PBKDFargon2i, argon2id, pbkdf2

    You can create a secret in the system namespace using kubectl or the Harvester UI (Edit as YAML feature). Resources in the system namespace are not displayed on the Harvester UI Secrets screen.

  • StorageClass: Images are encrypted using Longhorn, so required fields must be passed to the Longhorn CSI Driver. You can specify the encryption secret when creating a StorageClass. For more information, see Image StorageClass.

    Example of a StorageClass:

    allowVolumeExpansion: true
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: encryption
    parameters:
      csi.storage.k8s.io/node-publish-secret-name: encryption
      csi.storage.k8s.io/node-publish-secret-namespace: default
      csi.storage.k8s.io/node-stage-secret-name: encryption
      csi.storage.k8s.io/node-stage-secret-namespace: default
      csi.storage.k8s.io/provisioner-secret-name: encryption
      csi.storage.k8s.io/provisioner-secret-namespace: default
      encrypted: "true"
      migratable: "true"
      numberOfReplicas: "3"
      staleReplicaTimeout: "2880"
    provisioner: driver.longhorn.io
    reclaimPolicy: Delete
    volumeBindingMode: Immediate
    important

    You can create a secret in the system namespace using the Harvester UI (Edit as YAML feature) and kubectl. Resources in the system namespace are not displayed on the Harvester UI Secrets screen.

Encrypt a Virtual Machine Image​

  1. On the Harvester UI, go to Images.

  2. Click Create.

  3. Specify a namespace and a name.

  4. On the Basics tab, select Encrypt and then select a source image.

  5. On the Storage tab, select a StorageClass that includes encryption-related fields.

    Harvester passes the required fields to Longhorn.

  6. Click Create.

Decrypt a Virtual Machine Image​

  1. On the Harvester UI, go to Images.

  2. Click Create.

  3. Specify a namespace and a name.

  4. On the Basics tab, select Decrypt and then select a source image.

  5. On the Storage tab, select harvester-longhorn (Default) or another commonly used StorageClass.

    Harvester uses the StorageClass of the source image that you want to decrypt.

  6. Click Create.

Use an Image with Encrypted Volumes​

You must select the image that you want to use when creating a virtual machine.

The Virtual Machines screen displays the following icons and messages when volumes used by virtual machines are encrypted.

To determine which volumes are encrypted, check the Volumes tab on the Virtual Machine details screen.

Advanced Usage with Rancher Integration​

The secret is an unencrypted Base64-encoded string. To keep the secret safe, you can use projects and namespaces to isolate permissions. For more information, see Multi-Tenancy.

Limitations​

You cannot perform the following actions:

  • Export a new image from an encrypted image
  • Download an encrypted image
  • Upload an encrypted image