Encrypting communication with Etcd

StorageOS supports secure communication with an external etcd cluster using mutual TLS (mTLS). With mTLS both StorageOS and etcd authenticate each other ensuring that communication only happens between mutually authenticated end points, and that all communication is encrypted.

StorageOS uses the certificates and keys from a Secret to cypher and authenticate Etcd traffic.

How to create the certificates Secret

The client auth certificates need the following file names, in the Secret.

  • etcd-client-ca.crt - containing the etcd Certificate Authority certificate
  • etcd-client.crt - containing the etcd Client certificate
  • etcd-client.key - cotaining the etcd Client key
kubectl create secret -n storageos-etcd generic \
    etcd-client-tls \
    --from-file="etcd-client-ca.crt" \
    --from-file="etcd-client.crt" \
    --from-file="etcd-client.key"

How to use the mTLS certificates Secret with StorageOS

Below is an example StorageOSCluster resource that can be used to setup StorageOS with etcd using mTLS.

apiVersion: storageos.com/v1
kind: StorageOSCluster
metadata:
  name: storageos-cluster
  namespace: "storageos-operator"
spec:
  # StorageOS Pods are in kube-system by default
  secretRefName: "storageos-api"
  secretRefNamespace: "default"
  images:
    nodeContainer: "storageos/node:v2.2.0"
  namespace: "storageos"
  # External mTLS secured etcd cluster specific properties
  tlsEtcdSecretRefName: "etcd-client-tls"                                   # Secret containing etcd client certificates
  tlsEtcdSecretRefNamespace: "etcd"                                         # Namespace of the client certificates secret
  kvBackend:
    address: "https://storageos-etcd-cluster-client.storagos-etcd.svc:2379" # Etcd client service address.
    backend: "etcd"                                                         # Backend type

tlsEtcdSecretRefName and tlsEtcdSecretRefNamespace are used to pass a reference to the Secret.

The StorageOS operator uses the etcd secret that contains the client certificates, to build a secret in the StorageOS installation namespace. This secret contains the certificate filenames and certificate file contents. The StorageOS daemonset that is created by the operator mounts the secret as a volume so that the certificate files are available inside the pod. Environment variables containing the file paths are passed to the StorageOS process in order to use the files from the mounted path.

A worked example of setting up StorageOS with external etcd using mTLS is avaliable here. For ease of use the example uses the CoreOS etcd operator and the CoreOS guide The example uses the CoreOS etcd operator and follows the CoreOS guide for Cluster TLS.