How to Configure TLS Between LINSTOR Controller and LINSTOR Satellite

This guide shows you how to set up TLS between LINSTOR® Controller and LINSTOR Satellite.

To complete this guide, you should be familiar with:

• editing LinstorCluster and LinstorSatelliteConfiguration resources.
• using the LINSTOR client to verify success.
• using either cert-manager or openssl to create TLS certificates.

Provision Keys and Certificates Using cert-manager

This method requires a working cert-manager deployment in your cluster. For an alternative way to provision keys and certificates, see the openssl section below.

LINSTOR Controller and Satellite only need to trust each other, so it is good practice to have a CA only for those components. Apply the following YAML to create a new Issuer:

---
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: ca-bootstrapper
  namespace: piraeus-datastore
spec:
  selfSigned: { }
---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: linstor-internal-ca
  namespace: piraeus-datastore
spec:
  commonName: linstor-internal-ca
  secretName: linstor-internal-ca
  duration: 87600h # 10 years
  isCA: true
  usages:
    - signing
    - key encipherment
    - cert sign
  issuerRef:
    name: ca-bootstrapper
    kind: Issuer
---
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: linstor-internal-ca
  namespace: piraeus-datastore
spec:
  ca:
    secretName: linstor-internal-ca

Then, configure this new issuer to let the Operator provision the needed certificates:

---
apiVersion: piraeus.io/v1
kind: LinstorCluster
metadata:
  name: linstorcluster
spec:
  internalTLS:
    certManager:
      name: linstor-internal-ca
      kind: Issuer
---
apiVersion: piraeus.io/v1
kind: LinstorSatelliteConfiguration
metadata:
  name: internal-tls
spec:
  internalTLS:
    certManager:
      name: linstor-internal-ca
      kind: Issuer

This completes the necessary steps for secure TLS connections between LINSTOR Controller and Satellite using cert-manager. Skip to the last section to verify TLS is working.

Provision Keys and Certificates Using openssl

If you completed the cert-manager section above, skip directly to the verifying the configuration below.

This method requires the openssl program on the command line. For an alternative way to provision keys and certificates, see the cert-manager section above.

First, create a new Certificate Authority using a new key and a self-signed certificate, valid for 10 years:

openssl req -new -newkey rsa:4096 -days 3650 -nodes -x509 -keyout ca.key -out ca.crt -subj "/CN=linstor-internal-ca"

Then, create two new keys, one for the LINSTOR Controller, one for all Satellites:

openssl genrsa -out controller.key 4096
openssl genrsa -out satellite.key 4096

Next, we will create a certificate for each key, valid for 10 years, signed by the Certificate Authority:

openssl req -new -sha256 -key controller.key -subj "/CN=linstor-controller" -out controller.csr
openssl req -new -sha256 -key satellite.key -subj "/CN=linstor-satellite" -out satellite.csr
openssl x509 -req -in controller.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out controller.crt -days 3650 -sha256
openssl x509 -req -in satellite.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out satellite.crt -days 3650 -sha256

Now, we create Kubernetes secrets from the created keys and certificates:

kubectl create secret generic linstor-controller-internal-tls -n piraeus-datastore --type=kubernetes.io/tls --from-file=ca.crt=ca.crt --from-file=tls.crt=controller.crt --from-file=tls.key=controller.key
kubectl create secret generic linstor-satellite-internal-tls -n piraeus-datastore --type=kubernetes.io/tls --from-file=ca.crt=ca.crt --from-file=tls.crt=satellite.crt --from-file=tls.key=satellite.key

Finally, configure the Operator resources to reference the newly created secrets:

apiVersion: piraeus.io/v1
kind: LinstorCluster
metadata:
  name: linstorcluster
spec:
  internalTLS:
    secretName: linstor-controller-internal-tls
---
apiVersion: piraeus.io/v1
kind: LinstorSatelliteConfiguration
metadata:
  name: internal-tls
spec:
  internalTLS:
    secretName: linstor-satellite-internal-tls

Verifying TLS Configuration

You can verify the secure TLS connection between LINSTOR Controller and Satellite by checking the output of the linstor node list command. If TLS is enabled, you will see (SSL) next to the active satellite address:

$ kubectl exec -n piraeus-datastore deploy/linstor-controller -- linstor node list
+---------------------------------------------------------------------+
| Node               | NodeType  | Addresses                 | State  |
|=====================================================================|
| node01.example.com | SATELLITE | 10.116.72.142:3367 (SSL)  | Online |
| node02.example.com | SATELLITE | 10.127.183.140:3367 (SSL) | Online |
| node03.example.com | SATELLITE | 10.125.97.50:3367 (SSL)   | Online |
+---------------------------------------------------------------------+

If you see (PLAIN) instead, this indicates that the TLS configuration was not applied successfully. Check the status of the LinstorCluster and LinstorSatellite resource.

If you see (SSL), but the node remains offline, this usually indicates that a certificate is not trusted by the other party. Verify that the Controller's tls.crt is trusted by the Satellite's ca.crt and vice versa. The following script provides a quick way to verify that one TLS certificate is trusted by another:

function k8s_secret_trusted_by() {
    kubectl get secret -n piraeus-datastore -ogo-template='{{ index .data "tls.crt" | base64decode }}' "$1" > $1.tls.crt
    kubectl get secret -n piraeus-datastore -ogo-template='{{ index .data "ca.crt" | base64decode }}' "$2" > $2.ca.crt
    openssl verify -CAfile $2.ca.crt $1.tls.crt
}
k8s_secret_trusted_by satellite-tls controller-tls
# Expected output:
# satellite-tls.tls.crt: OK

All available options are documented in the reference for LinstorCluster and LinstorSatelliteConfiguration.