controller_kind.go

// Copyright 2018 The Operator-SDK Authors
//
// 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 scaffold

import (
	"path/filepath"

	"github.com/operator-framework/operator-sdk/pkg/scaffold/input"
)

// ControllerKind is the input needed to generate a pkg/controller/<kind>/<kind>_controller.go file
type ControllerKind struct {
	input.Input

	// Resource defines the inputs for the controller's primary resource
	Resource *Resource
}

func (s *ControllerKind) GetInput() (input.Input, error) {
	if s.Path == "" {
		fileName := s.Resource.LowerKind + "_controller.go"
		s.Path = filepath.Join(ControllerDir, s.Resource.LowerKind, fileName)
	}
	// Error if this file exists.
	s.IfExistsAction = input.Error
	s.TemplateBody = controllerKindTemplate
	return s.Input, nil
}

const controllerKindTemplate = `package {{ .Resource.LowerKind }}

import (
	"context"
	"log"

	{{ .Resource.Group}}{{ .Resource.Version }} "{{ .Repo }}/pkg/apis/{{ .Resource.Group}}/{{ .Resource.Version }}"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

/**
* USER ACTION REQUIRED: This is a scaffold file intended for the user to modify with their own Controller
* business logic.  Delete these comments after modifying this file.*
 */

// Add creates a new {{ .Resource.Kind }} Controller and adds it to the Manager. The Manager will set fields on the Controller
// and Start it when the Manager is Started.
func Add(mgr manager.Manager) error {
	return add(mgr, newReconciler(mgr))
}

// newReconciler returns a new reconcile.Reconciler
func newReconciler(mgr manager.Manager) reconcile.Reconciler {
	return &Reconcile{{ .Resource.Kind }}{client: mgr.GetClient(), scheme: mgr.GetScheme()}
}

// add adds a new Controller to mgr with r as the reconcile.Reconciler
func add(mgr manager.Manager, r reconcile.Reconciler) error {
	// Create a new controller
	c, err := controller.New("{{ .Resource.LowerKind }}-controller", mgr, controller.Options{Reconciler: r})
	if err != nil {
		return err
	}

	// Watch for changes to primary resource {{ .Resource.Kind }}
	err = c.Watch(&source.Kind{Type: &{{ .Resource.Group}}{{ .Resource.Version }}.{{ .Resource.Kind }}{}}, &handler.EnqueueRequestForObject{})
	if err != nil {
		return err
	}

	// TODO(user): Modify this to be the types you create that are owned by the primary resource
	// Watch for changes to secondary resource Pods and requeue the owner {{ .Resource.Kind }}
	err = c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForOwner{
		IsController: true,
		OwnerType:    &{{ .Resource.Group}}{{ .Resource.Version }}.{{ .Resource.Kind }}{},
	})
	if err != nil {
		return err
	}

	return nil
}

var _ reconcile.Reconciler = &Reconcile{{ .Resource.Kind }}{}

// Reconcile{{ .Resource.Kind }} reconciles a {{ .Resource.Kind }} object
type Reconcile{{ .Resource.Kind }} struct {
	// This client, initialized using mgr.Client() above, is a split client
	// that reads objects from the cache and writes to the apiserver
	client client.Client
	scheme *runtime.Scheme
}

// Reconcile reads that state of the cluster for a {{ .Resource.Kind }} object and makes changes based on the state read
// and what is in the {{ .Resource.Kind }}.Spec
// TODO(user): Modify this Reconcile function to implement your Controller logic.  This example creates
// a Pod as an example
// Note:
// The Controller will requeue the Request to be processed again if the returned error is non-nil or
// Result.Requeue is true, otherwise upon completion it will remove the work from the queue.
func (r *Reconcile{{ .Resource.Kind }}) Reconcile(request reconcile.Request) (reconcile.Result, error) {
	log.Printf("Reconciling {{ .Resource.Kind }} %s/%s\n", request.Namespace, request.Name)

	// Fetch the {{ .Resource.Kind }} instance
	instance := &{{ .Resource.Group}}{{ .Resource.Version }}.{{ .Resource.Kind }}{}
	err := r.client.Get(context.TODO(), request.NamespacedName, instance)
	if err != nil {
		if errors.IsNotFound(err) {
			// Request object not found, could have been deleted after reconcile request.
			// Owned objects are automatically garbage collected. For additional cleanup logic use finalizers.
			// Return and don't requeue
			return reconcile.Result{}, nil
		}
		// Error reading the object - requeue the request.
		return reconcile.Result{}, err
	}

	// Define a new Pod object
	pod := newPodForCR(instance)

	// Set {{ .Resource.Kind }} instance as the owner and controller
	if err := controllerutil.SetControllerReference(instance, pod, r.scheme); err != nil {
		return reconcile.Result{}, err
	}

	// Check if this Pod already exists
	found := &corev1.Pod{}
	err = r.client.Get(context.TODO(), types.NamespacedName{Name: pod.Name, Namespace: pod.Namespace}, found)
	if err != nil && errors.IsNotFound(err) {
		log.Printf("Creating a new Pod %s/%s\n", pod.Namespace, pod.Name)
		err = r.client.Create(context.TODO(), pod)
		if err != nil {
			return reconcile.Result{}, err
		}

		// Pod created successfully - don't requeue
		return reconcile.Result{}, nil
	} else if err != nil {
		return reconcile.Result{}, err
	}

	// Pod already exists - don't requeue
	log.Printf("Skip reconcile: Pod %s/%s already exists", found.Namespace, found.Name)
	return reconcile.Result{}, nil
}

// newPodForCR returns a busybox pod with the same name/namespace as the cr 
func newPodForCR(cr *{{ .Resource.Group}}{{ .Resource.Version }}.{{ .Resource.Kind }}) *corev1.Pod {
	labels := map[string]string{
		"app": cr.Name,
	}
	return &corev1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name:      cr.Name + "-pod",
			Namespace: cr.Namespace,
			Labels:    labels,
		},
		Spec: corev1.PodSpec{
			Containers: []corev1.Container{
				{
					Name:    "busybox",
					Image:   "busybox",
					Command: []string{"sleep", "3600"},
				},
			},
		},
	}
}
`