Enable Persistence In EMQX Cluster

Task Target

Configure EMQX 5.x cluster Core node persistence through volumeClaimTemplates field.

Configure EMQX Cluster Persistence

The following is the relevant configuration of EMQX Custom Resource. You can choose the corresponding APIVersion according to the version of EMQX you want to deploy. For the specific compatibility relationship, please refer to EMQX Operator Compatibility:

apps.emqx.io/v2beta1 EMQX supports configuration of EMQX cluster Core node persistence through .spec.coreTemplate.spec.volumeClaimTemplates field. The semantics and configuration of .spec.coreTemplate.spec.volumeClaimTemplates field are consistent with PersistentVolumeClaimSpec of Kubernetes, and its configuration can refer to the document: PersistentVolumeClaimSpec.

When the user configures the .spec.coreTemplate.spec.volumeClaimTemplates field, EMQX Operator will mount the /opt/emqx/data directory in the EMQX container to StorageClass in the PV and PVC created, when the EMQX Pod is deleted, the PV and PVC will not be deleted, so as to achieve the purpose of saving EMQX runtime data. For more information about PV and PVC, refer to the document Persistent Volumes.

• Save the following content as a YAML file and deploy it via the kubectl apply command

  apiVersion: apps.emqx.io/v2beta1
  kind: EMQX
  metadata:
    name: emqx
  spec:
    image: emqx/emqx-enterprise:6.0.0
    config:
      data: |
        license {
          key = "..."
        }
    coreTemplate:
      spec:
        volumeClaimTemplates:
          storageClassName: standard
          resources:
            requests:
              storage: 20Mi
          accessModes:
            - ReadWriteOnce
        replicas: 3
    listenersServiceTemplate:
      spec:
        type: LoadBalancer
    dashboardServiceTemplate:
      spec:
        type: LoadBalancer

  storageClassName field indicates the name of the StorageClass. You can use the command kubectl get storageclass to get the StorageClass that already exists in the Kubernetes cluster, or you can create a StorageClass according to your own needs.

• Wait for EMQX cluster to be ready, you can check the status of the EMQX cluster through kubectl get command, please make sure STATUS is Running, this may take some time

  $ kubectl get emqx emqx
  NAME   IMAGE                              STATUS    AGE
  emqx   emqx/emqx-enterprise:6.0.0  Running   10m

• Obtain the Dashboard External IP of the EMQX cluster and access the EMQX console

  EMQX Operator will create two EMQX Service resources, one is emqx-dashboard and the other is emqx-listeners, corresponding to EMQX console and EMQX listening port respectively.

  $ kubectl get svc emqx-dashboard -o json | jq '.status.loadBalancer.ingress[0].ip'
  
  192.168.1.200

  Access http://192.168.1.200:18083 through a browser, and use the default username and password admin/public to login EMQX console.

Verify EMQX Cluster Persistence

Verification scheme: 1) Passed in the old EMQX Dashboard creates a test rule; 2) Deletes the old cluster; 3) Recreates the EMQX cluster,and checks whether the previously created rule exists through the Dashboard.

• Access EMQX Dashboard through browser to create test rules

  external_ip=$(kubectl get svc emqx-listeners -o json | jq '.status.loadBalancer.ingress[0].ip')

  Login EMQX Dashboard by accessing http://${external_ip}:18083, and click Data Integration → Rules to enter the page for creating rules. Let’s first click the button to add an action Add a response action for this rule, and then click Create to generate a rule, as shown in the following figure:

  

  When our rule is successfully created, a rule record will appear on the page with the rule ID: emqx-persistent-test, as shown in the figure below:

  

• delete old EMQX cluster

  Execute the following command to delete the EMQX cluster:

  $ kubectl delete -f emqx.yaml
  
  emqx.apps.emqx.io "emqx" deleted
  # emqxenterprise.apps.emqx.io "emqx" deleted

  emqx-persistent.yaml is the YAML file used to deploy the EMQX cluster for the first time in this article, and this file does not need to be changed.

• Recreate the EMQX cluster

  Execute the following command to recreate the EMQX cluster:

  $ kubectl apply -f emqx.yaml
  
  emqx.apps.emqx.io/emqx created
  # emqxenterprise.apps.emqx.io/emqx created

  Wait for the EMQX cluster to be ready, and then access the EMQX Dashboard through the browser to check whether the previously created rules exist, as shown in the following figure:

  

  It can be seen from the figure that the rule emqx-persistent-test created in the old cluster still exists in the new cluster, which means that the persistence we configured is in effect.