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Deep dive into ClusterProfiles

ClusterProfiles

ClusterProfile is the CustomerResourceDefinition used to instruct Sveltos which add-ons to deploy on a set of clusters.

Spec.ClusterSelector

clusterSelector field selects a set of managed clusters where listed add-ons and applications will be deployed.

clusterSelector: env=prod

Spec.HelmCharts

helmCharts field consists of a list of helm charts to be deployed to the clusters matching clusterSelector;

  helmCharts:
  - repositoryURL:    https://kyverno.github.io/kyverno/
    repositoryName:   kyverno
    chartName:        kyverno/kyverno
    chartVersion:     v3.0.1
    releaseName:      kyverno-latest
    releaseNamespace: kyverno
    helmChartAction:  Install

Spec.PolicyRefs

policyRefs field references a list of ConfigMaps/Secrets, each containing Kubernetes resources to be deployed in the clusters matching clusterSelector.

This field is a slice of PolicyRef structs. Each PolictRef has the following fields:

  • Kind: The kind of the referenced resource. The supported kinds are Secret and ConfigMap.
  • Namespace: The namespace of the referenced resource. This field is optional, and if empty, the namespace will be set to the matching cluster's namespace.
  • Name: The name of the referenced resource. This field must be at least one character long.
  • DeploymentType: The deployment type of the referenced resource. This field indicates whether the resource should be deployed to the management cluster (local) or the managed cluster (remote). The default value is Remote.
policyRefs:
- kind: Secret
  name: my-secret-1
  namespace: my-namespace-1
  deploymentType: Local
- kind: Remote
  name: my-configmap-1
  namespace: my-namespace-1
  deploymentType: Remote

Spec.KustomizationRefs

kustomizationRefs field is a list of sources containing kustomization files. Resources will be deployed in the clusters matching the clusterSelector specified.

This field is a slice of KustomizationRef structs. Each KustomizationRef has the following fields:

  • Kind: The kind of the referenced resource. The supported kinds are:

    • flux GitRepository, OCIRepository, Bucket: These kinds represent resources that store Kustomization manifests.
    • ConfigMap, Secret: These kinds represent resources that contain Kustomization manifests or overlays.

  • Namespace: The namespace of the referenced resource. This field is optional and can be left empty. If it is empty, the namespace will be set to the cluster's namespace.

  • Name: The name of the referenced resource. This field must be at least one character long.
  • Path: The path to the directory containing the kustomization.yaml file, or the set of plain YAMLs for which a kustomization.yaml should be generated. This field is optional and defaults to None, which means the root path of the SourceRef.
  • TargetNamespace: The target namespace for the Kustomization deployment. This field is optional and can be used to override the namespace specified in the kustomization.yaml file.
  • DeploymentType: The deployment type of the referenced resource. This field indicates whether the Kustomization deployment should be deployed to the management cluster (local) or the managed cluster (remote). The default value is Remote.

Spec.SyncMode

This field can be set to:

  • OneTime
  • Continuous
  • ContinuousWithDriftDetection
  • DryRun

Let's take a closer look at the OneTime syncMode option. Once you deploy a ClusterProfile with a OneTime configuration, Sveltos will check all of your clusters for a match with the clusterSelector. Any matching clusters will have the resources specified in the ClusterProfile deployed. However, if you make changes to the ClusterProfile later on, those changes will not be automatically deployed to already-matching clusters.

Now, if you're looking for real-time deployment and updates, the Continuous syncMode is the way to go. With Continuous, any changes made to the ClusterProfile will be immediately reconciled into matching clusters. This means that you can add new features, update existing ones, and remove them as necessary, all without lifting a finger. Sveltos will deploy, update, or remove resources in matching clusters as needed, making your life as a Kubernetes admin a breeze.

ContinuousWithDriftDetection instructs Sveltos to monitor the state of managed clusters and detect a configuration drift for any of the resources deployed because of that ClusterProfile. When Sveltos detects a configuration drift, it automatically re-syncs the cluster state back to the state described in the management cluster. To know more about configuration drift detection, refer to this section.

Imagine you're about to make some important changes to your ClusterProfile, but you're not entirely sure what the results will be. You don't want to risk causing any unwanted side effects, right? Well, that's where the DryRun syncMode configuration comes in. By deploying your ClusterProfile with this configuration, you can launch a simulation of all the operations that would normally be executed in a live run. The best part? No actual changes will be made to the matching clusters during this dry run workflow, so you can rest easy knowing that there won't be any surprises. To know more about dry run, refer to this section.

Spec.StopMatchingBehavior

The stopMatchingBehavior field specifies the behavior when a cluster no longer matches a ClusterProfile. By default, all Kubernetes resources and Helm charts deployed to the cluster will be removed. However, if StopMatchingBehavior is set to LeavePolicies, any policies deployed by the ClusterProfile will remain in the cluster.

For instance 

apiVersion: config.projectsveltos.io/v1alpha1
kind: ClusterProfile
metadata:
  name: kyverno
spec:
  stopMatchingBehavior: WithdrawPolicies
  clusterSelector: env=prod
  helmCharts:
  - repositoryURL:    https://kyverno.github.io/kyverno/
    repositoryName:   kyverno
    chartName:        kyverno/kyverno
    chartVersion:     v3.0.1
    releaseName:      kyverno-latest
    releaseNamespace: kyverno
    helmChartAction:  Install

When a cluster matches the ClusterProfile, Kyverno Helm chart will be deployed in such a cluster. If the cluster's labels are subsequently modified and cluster no longer matches the ClusterProfile, the Kyverno Helm chart will be uninstalled. However, if the stopMatchingBehavior property is set to LeavePolicies, Sveltos will retain the Kyverno Helm chart in the cluster.

Spec.Reloader

The reloader property determines whether rolling upgrades should be triggered for Deployment, StatefulSet, or DaemonSet instances managed by Sveltos and associated with this ClusterProfile when changes are made to mounted ConfigMaps or Secrets. When set to true, Sveltos automatically initiates rolling upgrades for affected Deployment, StatefulSet, or DaemonSet instances whenever any mounted ConfigMap or Secret is modified. This ensures that the latest configuration updates are applied to the respective workloads.

Please refer to this section for more information.

Spec.MaxUpdate

A ClusterProfile might match more than one cluster. When a change is maded to a ClusterProfile, by default all matching clusters are update concurrently. The maxUpdate field specifies the maximum number of Clusters that can be updated concurrently during an update operation triggered by changes to the ClusterProfile's add-ons or applications. The specified value can be an absolute number (e.g., 5) or a percentage of the desired cluster count (e.g., 10%). The default value is 100%, allowing all matching Clusters to be updated simultaneously. For instance, if set to 30%, when modifications are made to the ClusterProfile's add-ons or applications, only 30% of matching Clusters will be updated concurrently. Updates to the remaining matching Clusters will only commence upon successful completion of updates in the initially targeted Clusters. This approach ensures a controlled and manageable update process, minimizing potential disruptions to the overall cluster environment. Please refer to this section for more information.

Spec.ValidateHealths

The validateHealths property defines a set of Lua functions that Sveltos executes against the managed cluster to assess the health and status of the add-ons and applications specified in the ClusterProfile. These Lua functions act as validation checks, ensuring that the deployed add-ons and applications are functioning properly and aligned with the desired state. By executing these functions, Sveltos proactively identifies any potential issues or misconfigurations that could arise, maintaining the overall health and stability of the managed cluster.

The ValidateHealths property accepts a slice of Lua functions, where each function encapsulates a specific validation check. These functions can access the managed cluster's state to perform comprehensive checks on the add-ons and applications. The results of the validation checks are aggregated and reported back to Sveltos, providing valuable insights into the health and status of the managed cluster's components.

Lua's scripting capabilities offer flexibility in defining complex validation logic tailored to specific add-ons or applications.

Please refer to this section for more information.

Consider a scenario where a new cluster with the label env:prod is created. The following instructions guide Sveltos to:

  • Deploy Kyverno Helm chart;
  • Validate Deployment Health: Perform health checks on each deployment within the kyverno namespace. Verify that the number of active replicas matches the requested replicas;
  • Successful Deployment: Once the health checks are successfully completed, Sveltos considers the ClusterProfile as successfully deployed.
apiVersion: config.projectsveltos.io/v1alpha1
kind: ClusterProfile
metadata:
  name: kyverno
spec:
  clusterSelector: env=prod
  helmCharts:
  - repositoryURL:    https://kyverno.github.io/kyverno/
    repositoryName:   kyverno
    chartName:        kyverno/kyverno
    chartVersion:     v3.0.1
    releaseName:      kyverno-latest
    releaseNamespace: kyverno
    helmChartAction:  Install
    validateHealths:
    - name: deployment-health
      featureID: Helm
      group: "apps"
      version: "v1"
      kind: "Deployment"
      namespace: kyverno
      script: |
        function evaluate()
          hs = {}
          hs.healthy = false
          hs.message = "available replicas not matching requested replicas"
          if obj.status ~= nil then
            if obj.status.availableReplicas ~= nil then
              if obj.status.availableReplicas == obj.spec.replicas then
                hs.healthy = true
              end
            end
          end
          return hs
        end

Spec.TemplateResourceRefs

The templateResourceRefs property specifies a collection of resources to be gathered from the management cluster. The values extracted from these resources will be utilized to instantiate templates embedded within referenced PolicyRefs and Helm charts. Refer to template section for more info and examples.

Spec.DependsOn

The dependsOn property specifies a list of other ClusterProfiles that this instance relies on. In any managed cluster that matches to this ClusterProfile, the add-ons and applications defined in this instance will only be deployed after all add-ons and applications in the designated dependency ClusterProfiles have been successfully deployed.

For example, clusterprofile-a can depend on another clusterprofile-b. This implies that any Helm charts or raw YAML files associated with ClusterProfile A will not be deployed until all add-ons and applications specified in ClusterProfile B have been successfully provisioned.

apiVersion: config.projectsveltos.io/v1alpha1
kind: ClusterProfile
metadata:
  name: clusterprofile-a
spec:
  dependsOn:
  - clusterprofile_b