Ceph

Key Management System

Rook has the ability to encrypt OSDs of clusters running on PVC via the flag (encrypted: true) in your storageClassDeviceSets template. By default, the Key Encryption Keys (also known as Data Encryption Keys) are stored in a Kubernetes Secret. However, if a Key Management System exists Rook is capable of using it.

The security section contains settings related to encryption of the cluster.

security:
- kms: Key Management System settings
  - connectionDetails: the list of parameters representing kms connection details
  - tokenSecretName: the name of the Kubernetes Secret containing the kms authentication token

Supported KMS providers:

Vault
Vault

Rook supports storing OSD encryption keys in HashiCorp Vault KMS.

Authentication methods

Rook support two authentication methods:

token-based: a token is provided by the user and is stored in a Kubernetes Secret. It’s used to authenticate the KMS by the Rook operator. This has several pitfalls such as:
- when the token expires it must be renewed, so the secret holding it must be updated
- no token automatic rotation
Kubernetes Service Account uses Vault Kubernetes native authentication mechanism and alleviate some of the limitations from the token authentication such as token automatic renewal. This method is generally recommended over the token-based authentication.

Token-based authentication

When using the token-based authentication, a Kubernetes Secret must be created to hold the token. This is governed by the tokenSecretName parameter.

Note: Rook supports all the Vault environment variables.

The Kubernetes Secret rook-vault-token should contain:

apiVersion: v1
kind: Secret
metadata:
  name: rook-vault-token
  namespace: rook-ceph
data:
  token: <TOKEN> # base64 of a token to connect to Vault, for example: cy5GWXpsbzAyY2duVGVoRjhkWG5Bb3EyWjkK

You can create a token in Vault by running the following command:

vault token create -policy=rook

Refer to the official vault document for more details on how to create a token. For which policy to apply see the next section.

In order for Rook to connect to Vault, you must configure the following in your CephCluster template:

security:
  kms:
    # name of the k8s config map containing all the kms connection details
    connectionDetails:
      KMS_PROVIDER: vault
      VAULT_ADDR: https://vault.default.svc.cluster.local:8200
      VAULT_BACKEND_PATH: rook
      VAULT_SECRET_ENGINE: kv
      VAULT_AUTH_METHOD: token
    # name of the k8s secret containing the kms authentication token
    tokenSecretName: rook-vault-token

Kubernetes-based authentication

In order to use the Kubernetes Service Account authentication method, the following must be run to properly configure Vault:

ROOK_NAMESPACE=rook-ceph
ROOK_VAULT_SA=rook-vault-auth
ROOK_SYSTEM_SA=rook-ceph-system
ROOK_OSD_SA=rook-ceph-osd
VAULT_POLICY_NAME=rook

# create service account for vault to validate API token
kubectl -n "$ROOK_NAMESPACE" create serviceaccount "$ROOK_VAULT_SA"

# create the RBAC for this SA
kubectl -n "$ROOK_NAMESPACE" create clusterrolebinding vault-tokenreview-binding --clusterrole=system:auth-delegator --serviceaccount="$ROOK_NAMESPACE":"$ROOK_VAULT_SA"

# get the service account common.yaml created earlier
VAULT_SA_SECRET_NAME=$(kubectl -n "$ROOK_NAMESPACE" get sa "$ROOK_VAULT_SA" -o jsonpath="{.secrets[*]['name']}")

# Set SA_JWT_TOKEN value to the service account JWT used to access the TokenReview API
SA_JWT_TOKEN=$(kubectl -n "$ROOK_NAMESPACE" get secret "$VAULT_SA_SECRET_NAME" -o jsonpath="{.data.token}" | base64 --decode)

# Set SA_CA_CRT to the PEM encoded CA cert used to talk to Kubernetes API
SA_CA_CRT=$(kubectl -n "$ROOK_NAMESPACE" get secret "$VAULT_SA_SECRET_NAME" -o jsonpath="{.data['ca\.crt']}" | base64 --decode)

# get kubernetes endpoint
K8S_HOST=$(kubectl config view --minify --flatten -o jsonpath="{.clusters[0].cluster.server}")

# enable kubernetes auth
vault auth enable kubernetes

# To fetch the service account issuer
kubectl proxy &
proxy_pid=$!

# configure the kubernetes auth
vault write auth/kubernetes/config \
    token_reviewer_jwt="$SA_JWT_TOKEN" \
    kubernetes_host="$K8S_HOST" \
    kubernetes_ca_cert="$SA_CA_CRT" \
    issuer="$(curl --silent http://127.0.0.1:8001/.well-known/openid-configuration | jq -r .issuer)"

kill $proxy_pid

# configure a role for rook
vault write auth/kubernetes/role/"$ROOK_NAMESPACE" \
    bound_service_account_names="$ROOK_SYSTEM_SA","$ROOK_OSD_SA" \
    bound_service_account_namespaces="$ROOK_NAMESPACE" \
    policies="$VAULT_POLICY_NAME" \
    ttl=1440h

Once done, your CephCluster CR should look like:

security:
  kms:
    connectionDetails:
        KMS_PROVIDER: vault
        VAULT_ADDR: https://vault.default.svc.cluster.local:8200
        VAULT_BACKEND_PATH: rook/ver1
        VAULT_SECRET_ENGINE: kv
        VAULT_AUTH_METHOD: kubernetes
        VAULT_AUTH_KUBERNETES_ROLE: rook-ceph

General Vault configuration

As part of the token, here is an example of a policy that can be used:

path "rook/*" {
  capabilities = ["create", "read", "update", "delete", "list"]
}
path "sys/mounts" {
capabilities = ["read"]
}

You can write the policy like so and then create a token:

vault policy write rook /tmp/rook.hcl
vault token create -policy=rook

Key                  Value
---                  -----
token                s.FYzlo02cgnTehF8dXnAoq2Z9
token_accessor       oMo7sAXQKbYtxU4HtO8k3pko
token_duration       768h
token_renewable      true
token_policies       ["default" "rook"]
identity_policies    []
policies             ["default" "rook"]

In the above example, Vault’s secret backend path name is rook. It must be enabled with the following:

vault secrets enable -path=rook kv

If a different path is used, the VAULT_BACKEND_PATH key in connectionDetails must be changed.

TLS configuration

This is an advanced but recommended configuration for production deployments, in this case the vault-connection-details will look like:

security:
  kms:
    # name of the k8s config map containing all the kms connection details
    connectionDetails:
      KMS_PROVIDER: vault
      VAULT_ADDR: https://vault.default.svc.cluster.local:8200
      VAULT_CACERT: <name of the k8s secret containing the PEM-encoded CA certificate>
      VAULT_CLIENT_CERT: <name of the k8s secret containing the PEM-encoded client certificate>
      VAULT_CLIENT_KEY: <name of the k8s secret containing the PEM-encoded private key>
    # name of the k8s secret containing the kms authentication token
    tokenSecretName: rook-vault-token

Each secret keys are expected to be:

VAULT_CACERT: cert
VAULT_CLIENT_CERT: cert
VAULT_CLIENT_KEY: key

For instance VAULT_CACERT Secret named vault-tls-ca-certificate will look like:

apiVersion: v1
kind: Secret
metadata:
  name: vault-tls-ca-certificate
  namespace: rook-ceph
data:
  cert: <PEM base64 encoded CA certificate>

Note: if you are using self-signed certificates (not known/approved by a proper CA) you must pass VAULT_SKIP_VERIFY: true. Communications will remain encrypted but the validity of the certificate will not be verified.