Managing Plugins for multiple clusters

Managing Plugins for multiple clusters

This guide describes how to configure and deploy a Greenhouse Plugin with the same configuration into multiple clusters.

The PluginPreset resource is used to create and deploy Plugins with a the identical configuration into multiple clusters. The list of clusters the Plugins will be deployed to is determind by a LabelSelector.

As a result, whenever a cluster, that matches the ClusterSelector is onboarded or offboarded, the Controller for the PluginPresets will take care of the Plugin Lifecycle. This means creating or deleting the Plugin for the respective cluster.

The same validation applies to the PluginPreset as to the Plugin. This includes immutable PluginDefinition and ReleaseNamespace fields, as well as the validation of the OptionValues against the PluginDefinition.

In case the PluginPreset is updated all of the Plugin instances that are managed by the PluginPreset will be updated as well. Each Plugin instance that is created from a PluginPreset has a label greenhouse.sap/pluginpreset: <PluginPreset name>. Also the name of the Plugin follows the scheme <PluginPreset name>-<cluster name>.

Changes that are done directly on a Plugin which was created from a PluginPreset will be overwritten immediately by the PluginPreset Controller. All changes must be performed on the PluginPreset itself. If a Plugin already existed with the same name as the PluginPreset would create, this Plugin will be ignored in following reconciliations.

Example PluginPreset

apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: kube-monitoring-preset
  namespace: <organization namespace>
spec:
  plugin: # this embeds the PluginSpec
    displayName: <any human readable name>
    pluginDefinition: <PluginDefinition name> # k get plugindefinition
    releaseNamespace: <namespace> # namespace where the plugin is deployed to on the remote cluster. Will be created if not exists
    optionValues:
      - name: <from the PluginDefinition options>
        value: <from the PluginDefinition options>
      - ..
  clusterSelector: # LabelSelector for the clusters the Plugin should be deployed to
    matchLabels:
      <label-key>: <label-value>
  clusterOptionOverrides: # allows you to override specific options in a given cluster
    - clusterName: <cluster name where we want to override values>
      overrides:
        - name: <option name to override>
          value: <new value>
        - ..
    - ..