dSSM Database


The Service Proxy for Kubernetes (SPK) distributed Session State Management (dSSM) Pods provide centralized and persistent storage for the Service Proxy Traffic Management Microkernel (TMM) Pods. The dSSM Pods are Redis data structure stores that maintain application traffic data such as DNS/NAT46 translation mappings. The dSSM Pods bind to Kubernetes persistence volumes to persist data in the event of a container restart.

This document describes the dSSM Pods, and guides you through configuring and installing the f5-dssm-sentinel and f5-dssm-db containers.

_images/spk_info.png Note: To upgrade the dSSM databases and preserve all persisted data, review the Upgrading dSSM guide.

Sentinels and DBs

The dSSM Pods integrate as a StatefulSet, containing three dSSM Sentinel Pods and three dSSM DB Pods to maintain high availability. The Sentinel Pods elect and monitor a primary dSSM DB Pod, and if the primary dSSM DB Pod fails, a secondary DB will assume the primary role.

Additional high availability

The dSSM Pods also use the standard Kubernetes node affinity and PodDisruptionBudget features to maintain additional levels of high availability.


Each dSSM Sentinel and DB Pod schedules onto a unique cluster node by default. The dSSM scheduling behavior can be modified using the dSSM Helm affinity_type parameter:

Setting Description
required Ensures the target cluster node does not currently host a Pod with the app=f5-dssm-db annotation (default).
preferred Attempt to schedule Pods onto unique nodes, but two dSSM Pods may schedule onto a single node when no schedulable nodes exists.
custom Scheduling behavior may be tuned specifically to the cluster admins requirements using the dSSM values.yaml file.

Helm parameter examples:

  affinity_type: "required"

  affinity_type: "required"

_images/spk_info.png Kubernetes Assigning Pods overview.


A minimum of 2 dSSM Pods remain available at all times based on the dSSM Helm pod_disruption_budget parameter. This parameter blocks voluntary interruptions to the dSSM Pod’s Running status. For example, if three schedulable nodes are available, and the admin runs oc adm drain on two of nodes in quick succession, the second action will be blocked until another schedulable node is added to the cluster.

Helm parameter examples:

    min_available: 2

    min_available: 2

_images/spk_info.png Kubernetes Disruptions overview.

Sentinel Service

After installing dSSM, a dSSM Sentinel Service is created that receives data from TMM on TCP service port 26379, and forwards to the dSSM DB Pods using the same service port number. Ensure the Service port is available, and the cluster has CoreDNS enabled. In this example, the SPK components will need to resolve the f5-dssm-sentinel.spk-utilities hostname.

Example dSSM Service:

Name:              f5-dssm-sentinel
Namespace:         spk-utilities
Port:              sentinel  26379/TCP

Example dSSM deployment:


Secure communication

The TMM, dSSM Sentinel and dSSM DB Pods communicate over a mesh of secure channels. These channels are secured using SSL/TLS keys and certificates stored as Secrets in the cluster. When deploying dSSM, the first step involves creating the SSL/TLS keys and certificates, and installing them as Secrets. Ensure you understand the key points in the following subsections:

Certificate Validity

SSL/TLS certificates are valid for a specific period of time, and once they expire, secure connections fail when validating the certificate. When creating new SSL/TLS certificates for the secure dSSM channels, choose a period of one year, or two years to avoid connection failures.

Example Certificate Validity:

    Not Before: Jan 1  10:30:00 2021 GMT
    Not After : Jan 1  10:30:00 2022 GMT

Updating Secrets

If you plan to replace a current set of Secrets with a new set, you must restart both the dSSM and Service Proxy TMM Pods to begin using the new Secrets. It is important to understand that restarting the TMM Pods causes a brief interruption to traffic processing, and should be performed during a planned maintenance window. To restart dSMM and the Service Proxy TMM Pods, refer to the Restarting procedure.


Ensure you have:


Install the Secrets

Use the following steps to create the required SSL/TLS keys and certificates, and install them as Secrets in both the TMM and dSSM Namespaces:

Note: The commands used to generate the Secrets can be downloaded here.

  1. Change into the directory with the SPK files:

    cd <directory>

    In this example, the SPK files are in the spkinstall directory:

    cd spkinstall
  2. Create a new directory for the dSSM Secret keys and certificates, and change into the directory:

    mkdir <directory>
    cd <directory>

    In this example, a new directory named dssm_secrets is created and changed into:

    mkdir dssm_secrets
    cd dssm_secrets
  3. Create the dSSM Certificate Authority (CA) key and certificate:

    In this example, the CA signing certificate is valid for one year.

    openssl genrsa -out dssm-ca.key 4096
    openssl req -x509 -new -nodes -sha384 \
        -key dssm-ca.key -days 365 \
        -subj '/O=Redis Test/CN=Certificate Authority' \
        -out dssm-ca.crt
  4. Create the dSSM client key and certificate:

    In this example, the dSSM client certificate is valid for one year.

    openssl genrsa -out dssm-key.key 4096
    openssl req -new -sha384 -key dssm-key.key \
        -subj '/O=Redis Test/CN=Server' | \
        openssl x509 -req -sha384 -CA dssm-ca.crt \
            -CAkey dssm-ca.key -CAserial dssm-ca.txt \
            -CAcreateserial  -days 365 \
            -out dssm-cert.crt
  5. Create the mTLS certificate for the TMM and dSSM communication channels:

    _images/spk_info.png Note: The mTLS certificate can take up to a minute to generate.

    openssl dhparam -out dhparam2048.pem 2048
  6. Encode the keys and certificates:

    openssl base64 -A -in dssm-ca.crt -out dssm-ca-encode.crt
    openssl base64 -A -in dssm-cert.crt -out dssm-cert-encode.crt
    openssl base64 -A -in dhparam2048.pem -out dhparam2048-encode.pem
    openssl base64 -A -in dssm-key.key -out dssm-key-encode.key
  7. Create the Secret certificate object file:

    echo "apiVersion: v1" > certs-secret.yaml
    echo "kind: Secret" >> certs-secret.yaml
    echo "metadata:" >> certs-secret.yaml
    echo " name: dssm-certs-secret" >> certs-secret.yaml
    echo "data:" >> certs-secret.yaml
    echo " dssm-ca.crt: `cat dssm-ca-encode.crt`"  >> certs-secret.yaml
    echo " dssm-cert.crt: `cat dssm-cert-encode.crt`" >> certs-secret.yaml
    echo " dhparam2048.pem: `cat dhparam2048-encode.pem`" >> certs-secret.yaml
  8. Create the Secret key object file:

    echo "apiVersion: v1" > keys-secret.yaml
    echo "kind: Secret" >> keys-secret.yaml
    echo "metadata:" >> keys-secret.yaml
    echo " name: dssm-keys-secret" >> keys-secret.yaml
    echo "data:" >> keys-secret.yaml
    echo " dssm-key.key: `cat dssm-key-encode.key`" >> keys-secret.yaml
  9. Create a new Project for the dSSM Pods:

    _images/spk_info.png Note: If you created a Project for the Fluentd Pod, switch to the project with oc project spk-utilities.

    oc new-project <project>

    In this example, a new Project named spk-utilities is created:

    oc new-project spk-utilities
  10. Install the Secret key and certificate files to the dSSM Project:

    oc apply -f keys-secret.yaml -n <project>
    oc apply -f certs-secret.yaml -n <project>

    In this example, the Secrets install to the spk-utilities Project:

    oc apply -f keys-secret.yaml -n spk-utilities
    oc apply -f certs-secret.yaml -n spk-utilities

    The command response should state the Secrets have been created:

    secret/dssm-keys-secret created
    secret/dssm-certs-secret created
  11. Install the Secret key and certificate files to the SPK Controller Project:

    _images/spk_info.png Note: The Controller Project was created during the SPK Secrets installation.

    oc apply -f keys-secret.yaml -n <project>
    oc apply -f certs-secret.yaml -n <project>

    In the example, the Secrets install to the spk-ingress Project:

    oc apply -f keys-secret.yaml -n spk-ingress
    oc apply -f certs-secret.yaml -n spk-ingress

    The command response should state the Secrets have been created:

    secret/dssm-keys-secret created
    secret/dssm-certs-secret created

Install the Pods

Use the following steps to deploy the dSSM Pods with persistence.

  1. Change into local directory with the SPK TAR files, and ensure the Helm charts have been extracted:

    cd <directory>
    ls -1 tar

    In this example, the SPK files are in the spkinstall directory:

    cd spkinstall
    ls -1 tar

    In this example, the dSSM Helm chart is named f5-dssm-0.22.18.tgz:

  2. Add the dSSM serviceAccount to the Project’s privileged security context constraint (SCC):

    _images/spk_info.png Note: The f5-dssm serviceAccount name is based on the Helm release name. See Step 6.

    oc adm policy add-scc-to-user privileged -n <project> -z <serviceaccount>

    In this example, the f5-dssm serviceAccount is added to the spk-utilities Project’s privileged SCC:

    oc adm policy add-scc-to-user privileged -n spk-utilities -z f5-dssm
  3. Create a Helm values file named dssm-values, and set the image.repository parameters:

      repository: <registry>
          repository: <registry>
          repository: <registry>

    In this example, Helm pulls the f5-dssm-store images from registry.com:

      repository: registry.com
          repository: registry.com
          repository: registry.com
  4. Optional: If you deployed the Fluentd Logging Pod, you can send logging data to the f5-fluentd container by adding the fluentd.host parameters to the values file:

          host: '<fluentd hostname>'
          host: '<fluentd hostname>'

    In this example, the Fluentd container is deployed to the spk-utilities Project:

          host: 'f5-toda-fluentd.spk-utilities.svc.cluster.local.'
          host: 'f5-toda-fluentd.spk-utilities.svc.cluster.local.'
  5. Change to the dSSM database Project:

    oc project <dssm project>

    In this example, dSSM is in the spk-utilities Project:

    oc project spk-utilities
  6. Install the dSSM Pods:

    _images/spk_warn.png Important: The string f5-dssm is the Helm release name. If a different release name is used, ensure the name is added to the privileged SCC.

    helm install f5-dssm tar/f5-dssm-<tag>.tgz -f <values>.yaml 

    For example:

    helm install f5-dssm tar/f5-dssm-0.22.18.tgz -f dssm-values.yaml 
  7. All dSSM Pods will be available after the election process, which can take up to a minute.

    _images/spk_warn.png Important: DB entries may fail to be created during the election process if TMM installs prior to completion. TMM will connect after the process completes.

    oc get pods

    In this example, the dSSM Pods in the spk-utilities Project have completed the election process, and the Pod STATUS is Running:

    NAME                              READY   STATUS   
    f5-dssm-db-0                      1/1     Running   
    f5-dssm-db-1                      1/1     Running   
    f5-dssm-db-2                      1/1     Running   
    f5-dssm-sentinel-0                1/1     Running   
    f5-dssm-sentinel-1                1/1     Running   
    f5-dssm-sentinel-2                1/1     Running  
  8. The dSSM DB Pods should be bound to the persistent volumes:

    oc get pvc

    In this example, the dSSM Pod’s PVC STATUS is Bound:

    NAME                STATUS   VOLUME                                     
    data-f5-dssm-db-0   Bound    pvc-c7060354-64d2-456b-9328-aa38f19b44b5   
    data-f5-dssm-db-1   Bound    pvc-8358b993-bf21-4fd7-a0fa-ee84ec420aac  
    data-f5-dssm-db-2   Bound    pvc-de65ed0f-f616-4021-a158-e0e78ed4539e   

Next step

Continue to the SPK Licensing installation guide. To securely connect the TMM and dSSM Pods, add the following parameters to the SPK Controller Helm values file:

_images/spk_warn.png Important: Set the SESSIONDB_EXTERNAL_SERVICE parameter to the Project of the dSSM Pod.

    useExternalStorage: "true"

  - name: REDIS_CA_FILE
    value: "/etc/ssl/certs/dssm-ca.crt"
    value: "/etc/ssl/certs/dssm-cert.crt"
  - name: REDIS_AUTH_KEY
    value: "/etc/ssl/private/dssm-key.key"
    value: "true"
    value: "f5-dssm-sentinel.spk-utilities"


This procedure assumes that you have deployed the dSSM Pods, and have created a new set of Secrets to replace the existing Secrets. The new Secrets will not be used until the dSSM and TMM Pods have been restarted.

_images/spk_warn.png Important: Restarting the Service Proxy TMM Pods impacts traffic processing.

  1. Obtain the name and number of Service Proxy TMM Pods:

    oc get deploy -n <project> | grep tmm 

    In this example, there are 3 Service Proxy TMM Pods in the spk-ingress Project:

    oc get deploy -n spk-ingress | grep f5-tmm
    f5-tmm                 3/3     3       3      
  2. Scale the number of Service Proxy Pods to 0:

    oc scale deploy/f5-tmm --replicas=0 -n <project>

    In this example the TMM Pods are in the spk-ingress Project:

    oc scale deploy/f5-tmm --replicas=0 -n spk-ingress
  3. Wait 5 or 10 seconds for the TMM Pods to terminate, and scale the TMM Pods back to the previous number:

    oc scale deploy/f5-tmm --replicas=<number> -n <project>

    In this example the TMM Pods are scaled back to 3 in the spk-ingress Namespace:

    oc scale deploy/f5-tmm --replicas=3 -n spk-ingress
  4. Restart the dSSM Sentinel and DB Pods:

    The dSSM Sentinel and DB Pods run as StatefulSets, and will be restarted automatically.

    oc delete pods -l 'app in (f5-dssm-db, f5-dssm-sentinel)' -n <project>

    In this example, the Sentinel and DB Pods are in the spk-utilities Namespace:

    oc delete pods -l 'app in (f5-dssm-db, f5-dssm-sentinel)' -n spk-utilities
    pod "f5-dssm-db-0" deleted
    pod "f5-dssm-db-1" deleted
    pod "f5-dssm-db-2" deleted
    pod "f5-dssm-sentinel-0" deleted
    pod "f5-dssm-sentinel-1" deleted
    pod "f5-dssm-sentinel-2" deleted
  5. Verify the dSSM Pods STATUS is Running:

    oc get pods -n spk-utilities
    NAME                              READY   STATUS 
    f5-dssm-db-0                      2/2     Running
    f5-dssm-db-1                      2/2     Running
    f5-dssm-db-2                      2/2     Running 
    f5-dssm-sentinel-0                2/2     Running 
    f5-dssm-sentinel-1                2/2     Running
    f5-dssm-sentinel-2                2/2     Running
  6. The new Secrets should now be used to secure the dSSM channels.


Provide feedback to improve this document by emailing spkdocs@f5.com.