Encrypting Confidential Data at Rest

You can configure EKS Anywhere clusters to encrypt confidential API resource data, such as secrets, at-rest in etcd using a KMS encryption provider. EKS Anywhere supports a hybrid model for configuring etcd encryption where cluster admins are responsible for deploying and maintaining the KMS provider on the cluster and EKS Anywhere handles configuring kube-apiserver with the KMS properties.

Because of this model, etcd encryption can only be enabled on cluster upgrades after the KMS provider has been deployed on the cluster.

Before you begin

Before enabling etcd encryption, make sure you have done the following:

• Learn how encrypting confidential data works in Kubernetes by reading Encrypting Secret Data at Rest.
• Learn how Kubernetes uses KMS encryption providers to encrypt data by reading Using a KMS Provider for data encryption.
• Learn how you can use AWS KMS keys to encrypt data using AWS Encryption Provider.
• Create an EKS Anywhere cluster since encryption can only be enabled on already created clusters.
• Deploy a KMS provider on the cluster that the kube-apiserver can use to encrypt/decrypt secrets.
  AWS Encryption Provider is the recommended KMS provider for EKS Anywhere.

Example etcd encryption configuration

The following cluster spec enables etcd encryption configuration:

apiVersion: anywhere.eks.amazonaws.com/v1alpha1
kind: Cluster
metadata:
  name: my-cluster
  namespace: default
spec:
  ...
  etcdEncryption:
  - providers:
    - kms:
        cachesize: 1000
        name: example-kms-config
        socketListenAddress: unix:///var/run/kmsplugin/socket.sock
        timeout: 3s
    resources:
    - secrets

Description of etcd encryption fields

etcdEncryption

Key used to specify etcd encryption configuration for a cluster. This field is only supported on cluster upgrades.

• providers

  Key used to specify which encryption provider to use. Currently, only one provider can be configured.

  • kms

    Key used to configure KMS encryption provider.

    • name

      Key used to set the name of the KMS plugin. This cannot be changed once set.

    • endpoint

      Key used to specify the listen address of the gRPC server (KMS plugin). The endpoint is a UNIX domain socket.

    • cachesize

      Number of data encryption keys (DEKs) to be cached in the clear. When cached, DEKs can be used without another call to the KMS; whereas DEKs that are not cached require a call to the KMS to unwrap. If cachesize isn’t specified, a default of 1000 is used.

    • timeout

      How long should kube-apiserver wait for kms-plugin to respond before returning an error. If a timeout isn’t specified, a default timeout of 3s is used.

• resources

  Key used to specify a list of resources that should be encrypted using the corresponding encryption provider. These can be native Kubernetes resources such as secrets and configmaps or custom resource definitions such as clusters.anywhere.eks.amazonaws.com.

Example AWS Encryption Provider DaemonSet

Here’s a sample AWS encryption provider daemonset configuration.

apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: aws-encryption-provider
  name: aws-encryption-provider
  namespace: kube-system
spec:
  selector:
    matchLabels:
      app: aws-encryption-provider
  template:
    metadata:
      labels:
        app: aws-encryption-provider
    spec:
      containers:
      - image: <AWS_ENCRYPTION_PROVIDER_IMAGE>    # Specify the AWS KMS encryption provider image 
        name: aws-encryption-provider
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"
        command:
        - /aws-encryption-provider
        - --key=<KEY_ARN>                         # Specify the arn of KMS key to be used for encryption/decryption
        - --region=<AWS_REGION>                   # Specify the region in which the KMS key exists
        - --listen=<KMS_SOCKET_LISTEN_ADDRESS>    # Specify a socket listen address for the KMS provider. Example: /var/run/kmsplugin/socket.sock
        ports:
        - containerPort: 8080
          protocol: TCP
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
        volumeMounts:
          - mountPath: /var/run/kmsplugin
            name: var-run-kmsplugin
          - mountPath: /root/.aws
            name: aws-credentials
      tolerations:
      - key: "node-role.kubernetes.io/master"
        effect: "NoSchedule"
      - key: "node-role.kubernetes.io/control-plane"
        effect: "NoSchedule"
      volumes:
      - hostPath:
          path: /var/run/kmsplugin
          type: DirectoryOrCreate
        name: var-run-kmsplugin
      - hostPath:
          path: /etc/kubernetes/aws
          type: DirectoryOrCreate
        name: aws-credentials