Define HNCConfiguration CR and set up a reconciler for the CR.

This commit implements HNC type configuration by creating HNCConfiguration CR and setting up a corresponding reconciler for it. Specifically, it does the following:

 - Implements the Go structs for HNCConfiguration and generates corresponding yaml files by running "make manifests".
 - Creates a basic reconciler for HNCConfiguration and configures it in setup.go. The reconciler does the following:
    - Creates a default singleton if it does not exist.
    - Writes or updates the singleton on the apiserver.
    - Logs the Spec of the HNCConfiguration when a reconciliation happens.

Tested:
  - Verified that the CRD were created correctly.
  - Created a sample HNCConfiguration and applied to KIND.
  - Verified the logs are expected on a GKE cluster during a reconciliation.

Design doc: http://bit.ly/hnc-type-configuration
Issue: kubernetes-retired#411

incubator/hnc/api/v1alpha1/hnc_config.go

@@ -0,0 +1,104 @@
+/*
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1alpha1
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+// Constants for types and well-known names.
+const (
+	HNCConfigSingleton = "config"
+)
+
+// SynchronizationMode describes propogation mode of objects of the same kind.
+// The only three modes currently supported are "propagate", "ignore", and "remove".
+// See detailed definition below. An unsupported mode will be treated as "ignore".
+type SynchronizationMode string
+
+const (
+	// Propagate objects from ancestors to descendants and deletes obsolete descendants.
+	Propagate SynchronizationMode = "propagate"
+
+	// Ignore the modification of this type. New or changed objects will not be propagated,
+	// and obsolete objects will not be deleted. The inheritedFrom label is not removed.
+	// Any unknown mode is treated as ignore.
+	Ignore SynchronizationMode = "ignore"
+
+	// Remove all existing propagated copies.
+	Remove SynchronizationMode = "remove"
+)
+
+// TypeSynchronizationSpec defines the desired synchronization state of a specific kind.
+type TypeSynchronizationSpec struct {
+	// API version of the kind defined below. This is used to unambiguously identifies the kind.
+	APIVersion string `json:"apiVersion,omitempty"`
+	// Kind to be configured.
+	Kind string `json:"kind,omitempty"`
+	// Synchronization mode of the kind.
+	// +optional
+	Mode SynchronizationMode `json:"mode,omitempty"`
+}
+
+// TypeSynchronizationStatus defines the observed synchronization state of a specific kind.
+type TypeSynchronizationStatus struct {
+	// API version of the kind defined below. This is used to unambiguously identifies the kind.
+	APIVersion string `json:"apiVersion,omitempty"`
+	// Kind to be configured.
+	Kind string `json:"kind,omitempty"`
+
+	// Tracks the number of original objects that are being propagated to descendant namespaces.
+	// +kubebuilder:validation:Minimum=0
+	// +optional
+	NumPropagated *int32 `json:"numPropagated,omitempty"`
+}
+
+// +kubebuilder:object:root=true
+// +kubebuilder:resource:path=hncconfigurations,scope=Cluster
+
+// HNCConfiguration is a cluster-wide configuration for HNC as a whole. See details in http://bit.ly/hnc-type-configuration
+type HNCConfiguration struct {
+	metav1.TypeMeta   `json:",inline"`
+	metav1.ObjectMeta `json:"metadata,omitempty"`
+
+	Spec   HNCConfigurationSpec   `json:"spec,omitempty"`
+	Status HNCConfigurationStatus `json:"status,omitempty"`
+}
+
+// HNCConfigurationSpec defines the desired state of HNC configuration.
+type HNCConfigurationSpec struct {
+	// Types indicates the desired synchronization states of kinds, if any.
+	Types []TypeSynchronizationSpec `json:"types,omitempty"`
+}
+
+// HNCConfigurationStatus defines the observed state of HNC configuration.
+type HNCConfigurationStatus struct {
+	// Types indicates the observed synchronization states of kinds, if any.
+	Types []TypeSynchronizationStatus `json:"types,omitempty"`
+}
+
+// +kubebuilder:object:root=true
+
+// HNCConfigurationList contains a list of HNCConfiguration.
+type HNCConfigurationList struct {
+	metav1.TypeMeta `json:",inline"`
+	metav1.ListMeta `json:"metadata,omitempty"`
+	Items           []HNCConfiguration `json:"items"`
+}
+
+func init() {
+	SchemeBuilder.Register(&HNCConfiguration{}, &HNCConfigurationList{})
+}

incubator/hnc/config/crd/bases/hnc.x-k8s.io_hierarchyconfigurations.yaml

@@ -3,6 +3,8 @@
 apiVersion: apiextensions.k8s.io/v1beta1
 kind: CustomResourceDefinition
 metadata:
+  annotations:
+    controller-gen.kubebuilder.io/version: v0.2.4
   creationTimestamp: null
   name: hierarchyconfigurations.hnc.x-k8s.io
 spec:
@@ -12,7 +14,7 @@ spec:
     listKind: HierarchyConfigurationList
     plural: hierarchyconfigurations
     singular: hierarchyconfiguration
-  scope: ""
+  scope: Namespaced
   validation:
     openAPIV3Schema:
       description: Hierarchy is the Schema for the hierarchies API

incubator/hnc/config/crd/bases/hnc.x-k8s.io_hncconfigurations.yaml

@@ -0,0 +1,95 @@
+
+---
+apiVersion: apiextensions.k8s.io/v1beta1
+kind: CustomResourceDefinition
+metadata:
+  annotations:
+    controller-gen.kubebuilder.io/version: v0.2.4
+  creationTimestamp: null
+  name: hncconfigurations.hnc.x-k8s.io
+spec:
+  group: hnc.x-k8s.io
+  names:
+    kind: HNCConfiguration
+    listKind: HNCConfigurationList
+    plural: hncconfigurations
+    singular: hncconfiguration
+  scope: Cluster
+  validation:
+    openAPIV3Schema:
+      description: HNCConfiguration is a cluster-wide configuration for HNC as a whole.
+        See details in http://bit.ly/hnc-type-configuration
+      properties:
+        apiVersion:
+          description: 'APIVersion defines the versioned schema of this representation
+            of an object. Servers should convert recognized schemas to the latest
+            internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#resources'
+          type: string
+        kind:
+          description: 'Kind is a string value representing the REST resource this
+            object represents. Servers may infer this from the endpoint the client
+            submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds'
+          type: string
+        metadata:
+          type: object
+        spec:
+          description: HNCConfigurationSpec defines the desired state of HNC configuration.
+          properties:
+            types:
+              description: Types indicates the desired synchronization states of kinds,
+                if any.
+              items:
+                description: TypeSynchronizationSpec defines the desired synchronization
+                  state of a specific kind.
+                properties:
+                  apiVersion:
+                    description: API version of the kind defined below. This is used
+                      to unambiguously identifies the kind.
+                    type: string
+                  kind:
+                    description: Kind to be configured.
+                    type: string
+                  mode:
+                    description: Synchronization mode of the kind.
+                    type: string
+                type: object
+              type: array
+          type: object
+        status:
+          description: HNCConfigurationStatus defines the observed state of HNC configuration.
+          properties:
+            types:
+              description: Types indicates the observed synchronization states of
+                kinds, if any.
+              items:
+                description: TypeSynchronizationStatus defines the observed synchronization
+                  state of a specific kind.
+                properties:
+                  apiVersion:
+                    description: API version of the kind defined below. This is used
+                      to unambiguously identifies the kind.
+                    type: string
+                  kind:
+                    description: Kind to be configured.
+                    type: string
+                  numPropagated:
+                    description: Tracks the number of original objects that are being
+                      propagated to descendant namespaces.
+                    format: int32
+                    minimum: 0
+                    type: integer
+                type: object
+              type: array
+          type: object
+      type: object
+  version: v1alpha1
+  versions:
+  - name: v1alpha1
+    served: true
+    storage: true
+status:
+  acceptedNames:
+    kind: ""
+    plural: ""
+  conditions: []
+  storedVersions: []

incubator/hnc/config/crd/kustomization.yaml

@@ -3,6 +3,7 @@
 # It should be run by config/default
 resources:
 - bases/hnc.x-k8s.io_hierarchyconfigurations.yaml
+- bases/hnc.x-k8s.io_hncconfigurations.yaml
 # +kubebuilder:scaffold:crdkustomizeresource
 
 patchesStrategicMerge:

incubator/hnc/config/samples/hnc_v1_config.yaml

@@ -0,0 +1,12 @@
+apiVersion: hnc.x-k8s.io/v1alpha1
+kind: HNCConfiguration
+metadata:
+  name: config
+spec:
+  types:
+    - apiVersion: v1
+      kind: Secret
+      mode: propagate
+    - apiVersion: rbac.authorization.k8s.io/v1
+      kind: Role
+      mode: ignore