PluginPresets

A PluginPreset is used to configure Plugins for a set of Clusters. This allows administrators to define standard configurations for Clusters in the same environment or with similar requirements. Greenhouse will create Plugins based on the PluginPreset for each Cluster that matches the specified selector.

Example PluginPreset Spec

apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: perses-preset
  namespace: example-organization
spec:
  clusterOptionOverrides:
    - clusterName: example-cluster
      overrides:
      - name: perses.serviceMonitor.selfMonitor
        value: true
      - name: perses.serviceMonitor.labels
        value:
          plugin: kube-monitoring
  clusterSelector:
    matchExpressions:
    - key: cluster-type
      operator: In
      values:
      - observability
  deletionPolicy: Delete
  plugin:
    optionValues:
    - name: perses.sidecar.enabled
      value: true
    - name: perses.ingress.host
      expression: |
        "perses.${global.greenhouse.clusterName}.example.com"        
    pluginDefinitionRef:
      kind: ClusterPluginDefinition
      name: perses
    releaseName: perses
    releaseNamespace: kube-monitoring

Writing a PluginPreset Spec

.spec.plugin is the template for the Plugins that will be created for each matching Cluster. This field has the same structure as the PluginSpec. Only .spec.clusterName is not allowed in the PluginPreset’s Plugin template, as the Cluster name is determined by the matching Clusters.

ℹ️ A non-existing PluginDefinition can be referenced in the PluginPreset. The PluginPreset will be reconciled once the PluginDefinition is created. This allows rolling out new PluginDefinitions via a Catalog together with the PluginPresets that reference them.

spec:
  plugin:
    optionValues:
    - name: perses.sidecar.enabled
      value: true
    pluginDefinitionRef:
      kind: ClusterPluginDefinition
      name: perses
    releaseName: perses
    releaseNamespace: kube-monitoring

.spec.clusterSelector is a required field that specifies the label selector used to list the Clusters for which Plugins will be created based on this PluginPreset.

spec:
  clusterSelector:
    matchExpressions:
    - key: cluster-type
      operator: In
      values:
      - observability

| ⚠️ Changing the clusterSelector may result in the creation or deletion of Plugins for Clusters that start or stop matching the selector. |

.spec.clusterOptionOverrides is an optional field that can be used to provide per-Cluster overrides for the Plugin’s OptionValues. This can be used to customize the configuration of the Plugin for specific Clusters.

spec:
  clusterOptionOverrides:
    - clusterName: example-cluster
      overrides:
      - name: perses.serviceMonitor.selfMonitor
        value: true

.spec.deletionPolicy is an optional field that specifies the behaviour when a PluginPreset is deleted. The possible values are Delete and Retain. If set to Delete (the default), all Plugins created by the PluginPreset will also be deleted when the PluginPreset is deleted. If set to Retain, the Plugins will remain after the PluginPreset is deleted or if the Cluster stops matching the selector.

CEL Expressions in OptionValues

PluginPresets support CEL (Common Expression Language) expressions in optionValues. Expressions are evaluated during PluginPreset reconciliation, and the resulting Plugin contains only the resolved values with no expression fields remaining.

Expressions use the ${...} syntax to reference dynamic values:

spec:
  plugin:
    optionValues:
    - name: app.hostname
      expression: |
        "myapp.${global.greenhouse.clusterName}.example.com"

When this PluginPreset creates a Plugin for a cluster named cluster-a, the Plugin will contain:

spec:
  optionValues:
  - name: app.hostname
    value: "myapp.cluster-a.example.com"

Available Variables

Variable	Description	Example Value
`global.greenhouse.clusterName`	Name of the target cluster	`cluster-a`
`global.greenhouse.organizationName`	Organization namespace	`my-org`
`global.greenhouse.baseDomain`	Base DNS domain	`greenhouse.example.com`
`global.greenhouse.ownedBy`	Owning `Team`	`team-1`
`global.greenhouse.metadata.*`	Cluster metadata labels	`eu-de-1`

ℹ️ global.greenhouse.metadata.* values are derived from cluster labels prefixed with metadata.greenhouse.sap/. For example, the label metadata.greenhouse.sap/region: eu-de-1 becomes available as global.greenhouse.metadata.region.

⚠️ global.greenhouse.clusterNames and global.greenhouse.teamNames were removed. An expression still referencing either of them fails to evaluate and blocks the PluginPreset from rolling out its Plugins. See Injected Greenhouse Values.

Examples

Hostname per cluster:

- name: ingress.host
  expression: |
    "service.${global.greenhouse.clusterName}.example.com"    
# Result for cluster "cluster-a": "service.cluster-a.example.com"

Using cluster metadata:

- name: ingress.host
  expression: |
    "service.${global.greenhouse.metadata.region}.example.com"    
# Result: "service.eu-de-1.example.com"
# Requires label metadata.greenhouse.sap/region on the cluster

Combining variables:

- name: app.fqdn
  expression: |
    "${global.greenhouse.clusterName}-${global.greenhouse.organizationName}"    
# Result for cluster "cluster-a" in org "my-org": "cluster-a-my-org"

Expressions in ClusterOptionOverrides

Expressions can also be used in clusterOptionOverrides. Overrides are merged before expression evaluation, so override expressions are also resolved:

spec:
  plugin:
    optionValues:
    - name: app.mode
      value: "standard"
  clusterOptionOverrides:
    - clusterName: special-cluster
      overrides:
      - name: app.hostname
        expression: |
          "special.${global.greenhouse.metadata.region}.example.com"

ℹ️ Expressions are only evaluated in PluginPresets.

Feature Flag

CEL expression evaluation in PluginPresets requires the feature flag pluginPreset.expressionEvaluationEnabled to be set to true in the Greenhouse feature flags ConfigMap.

By default, this flag is false if it is unset or invalid. When disabled, PluginPresets containing expressions will be rejected with an error.

# greenhouse-feature-flags ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
  name: greenhouse-feature-flags
  namespace: greenhouse
data:
  pluginPreset: |
    expressionEvaluationEnabled: true

ValueFrom References Between PluginPresets

PluginPresets can reference option values from other PluginPresets using valueFrom.ref. This enables one PluginPreset to use resolved values from another, including values generated by CEL expressions.

Reference by Name

# Source PluginPreset - generates a hostname per cluster
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: backend-preset
spec:
  plugin:
    pluginDefinitionRef:
      name: backend-service
    optionValues:
      - name: backend.hostname
        expression: |
          "backend.${global.greenhouse.clusterName}.example.com"          
  clusterSelector:
    matchLabels:
      env: production
---
# Consumer PluginPreset - references the backend hostname
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: frontend-preset
spec:
  plugin:
    pluginDefinitionRef:
      name: frontend-service
    optionValues:
      - name: frontend.backendUrl
        valueFrom:
          ref:
            kind: PluginPreset
            name: backend-preset
            expression: |
              ${spec.optionValues.filter(v, v.name == "backend.hostname")[0].value}              
  clusterSelector:
    matchLabels:
      env: production

The resulting Plugin will contain the resolved value. For example:

# If the matching cluster is named "production-eu":
spec:
  optionValues:
  - name: frontend.backendUrl
    value: "backend.production-eu.example.com"

Reference by Label Selector

When multiple PluginPresets need to be referenced, use a label selector. The CEL expression is evaluated against each matching PluginPreset and results are collected into an array.

# Multiple source PluginPresets with shared label
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: selector-source-a
  namespace: demo
  labels:
    e2e.greenhouse.sap/selector-test: "true"
spec:
  plugin:
    pluginDefinitionRef:
      name: perses
    releaseName: perses-sel-source-a
    releaseNamespace: kube-monitoring
    optionValues:
      - name: source.endpoint
        expression: |
          "endpoint-a.${global.greenhouse.clusterName}.example.com"          
  clusterSelector:
    matchLabels:
      greenhouse.sap/cluster: kind-greenhouse-remote
---
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: selector-source-b
  namespace: demo
  labels:
    e2e.greenhouse.sap/selector-test: "true"
spec:
  plugin:
    pluginDefinitionRef:
      name: perses
    releaseName: perses-sel-source-b
    releaseNamespace: kube-monitoring
    optionValues:
      - name: source.endpoint
        expression: |
          "endpoint-b.${global.greenhouse.clusterName}.example.com"          
  clusterSelector:
    matchLabels:
      greenhouse.sap/cluster: kind-greenhouse-remote
---
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: selector-consumer
  namespace: demo
spec:
  plugin:
    pluginDefinitionRef:
      name: perses
    releaseName: perses-sel-consumer
    releaseNamespace: kube-monitoring
    optionValues:
      - name: consumer.endpoints
        valueFrom:
          ref:
            kind: PluginPreset
            selector:
              matchLabels:
                e2e.greenhouse.sap/selector-test: "true"
            expression: |
              ${spec.optionValues.filter(v, v.name == "source.endpoint")[0].value}              
  clusterSelector:
    matchLabels:
      greenhouse.sap/cluster: kind-greenhouse-remote

The consumer Plugin will receive an array of all resolved values:

spec:
  optionValues:
  - name: consumer.endpoints
    value: [ "endpoint-a.kind-greenhouse-remote.example.com",
      "endpoint-b.kind-greenhouse-remote.example.com"]

Reference a Plugin

Set ref.kind to Plugin to read the option values of an existing Plugin instead of a PluginPreset. Name and label selector work the same way as above.

The Plugins created by a PluginPreset carry the label greenhouse.sap/pluginpreset: <preset name>, so a selector on that label collects one value per cluster the source preset rolls out to.

# Consumer PluginPreset - collects one host per cluster of the source preset
apiVersion: greenhouse.sap/v1alpha1
kind: PluginPreset
metadata:
  name: thanos-central
spec:
  plugin:
    pluginDefinitionRef:
      name: thanos
    optionValues:
      - name: thanos.query.stores
        valueFrom:
          ref:
            kind: Plugin
            selector:
              matchLabels:
                greenhouse.sap/pluginpreset: thanos-regional
            expression: |
              ${spec.optionValues.filter(v, v.name == "thanos.query.grpc.host")[0].value}              
  clusterSelector:
    matchLabels:
      env: production

Next to metadata and spec.optionValues, an expression on a Plugin reference can also read spec.clusterName and spec.releaseName.

CEL Expression Syntax for References

The expression field in valueFrom.ref supports multiple syntax styles:

New simplified syntax

expression: spec.optionValues.filter(v, v.name == "my.value")[0].value

With ${…} wrapper

expression: ${spec.optionValues.filter(v, v.name == "my.value")[0].value}

Legacy syntax (backward compatible)

expression: object.spec.optionValues.filter(v, v.name == "my.value")[0].value

⚠️ ref.kind accepts PluginPreset and Plugin only, and defaults to PluginPreset when left empty. Any other kind fails the resolution.

Feature Flags

Expression evaluation and ValueFrom.Ref resolution in PluginPresets are controlled by feature flags:

# greenhouse-feature-flags ConfigMap
pluginPreset: |
  expressionEvaluationEnabled: true
  integrationEnabled: true