machineimage_controller.go

// Copyright 2023 Dimitri Koshkin. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

/*
Copyright 2023.

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 controller

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/go-logr/logr"
	batchv1 "k8s.io/api/batch/v1"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/tools/record"
	"sigs.k8s.io/cluster-api/util/patch"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"

	kubernetesupgraderv1 "github.com/dkoshkin/kubernetes-upgrader/api/v1alpha1"
	"github.com/dkoshkin/kubernetes-upgrader/internal/jobs"
)

const (
	imageBuilderJobRequeueDelay = 1 * time.Minute
	imageBuilderJobRequeueNow   = 1 * time.Second
)

// MachineImageReconciler reconciles a MachineImage object.
type MachineImageReconciler struct {
	client.Client
	Scheme   *runtime.Scheme
	Recorder record.EventRecorder
}

//nolint:lll // This is generated code.
//+kubebuilder:rbac:groups=kubernetesupgraded.dimitrikoshkin.com,resources=machineimages,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=kubernetesupgraded.dimitrikoshkin.com,resources=machineimages/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=kubernetesupgraded.dimitrikoshkin.com,resources=machineimages/finalizers,verbs=update
//+kubebuilder:rbac:groups=batch,resources=jobs,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=core,resources=events,verbs=get;list;watch;create;patch

// Reconcile is part of the main kubernetes reconciliation loop which aims to
// move the current state of the cluster closer to the desired state.
//
// For more details, check Reconcile and its Result here:
// - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.15.0/pkg/reconcile
//
//nolint:dupl // Prefer readability to DRY.
func (r *MachineImageReconciler) Reconcile(
	ctx context.Context,
	req ctrl.Request,
) (_ ctrl.Result, rerr error) {
	logger := log.FromContext(ctx).
		WithValues("machineimage", req.Name, "namespace", req.Namespace)

	machineImage := &kubernetesupgraderv1.MachineImage{}
	if err := r.Get(ctx, req.NamespacedName, machineImage); err != nil {
		logger.Error(
			err,
			"unable to fetch MachineImage",
			"namespace", req.Namespace, "name", req.Name)
		if apierrors.IsNotFound(err) {
			return ctrl.Result{}, nil
		}
		//nolint:wrapcheck // No additional context to add.
		return ctrl.Result{}, err
	}

	// Initialize the patch helper
	patchHelper, err := patch.NewHelper(machineImage, r.Client)
	if err != nil {
		//nolint:wrapcheck // No additional context to add.
		return ctrl.Result{}, err
	}
	// Always attempt to Patch the MachineImage object and status after each reconciliation.
	defer func() {
		if err := patchMachineImage(ctx, patchHelper, machineImage); err != nil {
			logger.Error(err, "failed to patch MachineImage")
			if rerr == nil {
				rerr = err
			}
		}
	}()

	// Handle deleted clusters
	if !machineImage.DeletionTimestamp.IsZero() {
		return r.reconcileDelete(ctx, logger, machineImage)
	}

	// Handle non-deleted clusters
	return r.reconcileNormal(ctx, logger, machineImage)
}

//nolint:funlen // TODO(dkoshkin): Refactor.
func (r *MachineImageReconciler) reconcileNormal(
	ctx context.Context,
	logger logr.Logger,
	machineImage *kubernetesupgraderv1.MachineImage,
) (ctrl.Result, error) {
	logger.Info("Reconciling normal")

	jobManager := jobs.NewManager(r.Client, r.Scheme)

	logger.Info("Checking if job already exists")
	// Before doing anything check if a Job already exists.
	// If a job(s) does exist, use the latest one.
	latestJob, err := jobManager.Latest(ctx, machineImage)
	if err != nil {
		r.Recorder.Eventf(
			machineImage,
			corev1.EventTypeWarning,
			"GetLatestJobsError",
			"Error getting latest Job: %s",
			err,
		)
		//nolint:wrapcheck // No additional context to add.
		return ctrl.Result{}, err
	}
	if latestJob != nil {
		// This is needed to avoid a race condition of multiple Jobs getting created.
		// It's possible that the machineImage that is being reconciled does not have the job reference set.
		// Always set the reference to the first Job in the list.
		machineImage.Status.JobRef = latestJob
		return r.handleJob(ctx, logger, machineImage, jobManager)
	}

	if machineImage.Spec.ID != "" {
		logger.Info("Image already built, nothing to do")
		machineImage.Status.Ready = true
		machineImage.Status.Phase = kubernetesupgraderv1.MachineImagePhaseCreated
		return ctrl.Result{}, nil
	}

	logger.Info("Job reference not set, creating a new job")
	r.Recorder.Eventf(
		machineImage,
		corev1.EventTypeNormal,
		"CreatingJob",
		"Creating a new Job",
	)
	spec := &machineImage.Spec.JobTemplate.Spec
	jobRef, err := jobManager.Create(ctx, machineImage, spec)
	if err != nil {
		r.Recorder.Eventf(
			machineImage,
			corev1.EventTypeWarning,
			"CreatingJobError",
			"Error creating a new Job: %s",
			err,
		)
		//nolint:wrapcheck // No additional context to add.
		return ctrl.Result{}, err
	}
	logger.Info("Created a new Job", "name", jobRef.Name)
	machineImage.Status.JobRef = jobRef
	machineImage.Status.Phase = kubernetesupgraderv1.MachineImagePhaseBuilding

	return ctrl.Result{}, nil
}

func (r *MachineImageReconciler) reconcileDelete(
	_ context.Context,
	logger logr.Logger,
	_ *kubernetesupgraderv1.MachineImage,
) (ctrl.Result, error) {
	logger.Info("Reconciling delete")

	return ctrl.Result{}, nil
}

func (r *MachineImageReconciler) handleJob(
	ctx context.Context,
	logger logr.Logger,
	machineImage *kubernetesupgraderv1.MachineImage,
	jobManager jobs.Manager,
) (ctrl.Result, error) {
	logger.Info("Job reference set, checking status")
	status, id, err := jobManager.Status(ctx, machineImage.Status.JobRef)
	if err != nil {
		if apierrors.IsNotFound(err) {
			logger.Info("Referenced Job not found, setting reference to nil to recreate")
			machineImage.Status.JobRef = nil
			return ctrl.Result{RequeueAfter: imageBuilderJobRequeueNow}, nil
		}
		//nolint:wrapcheck // No additional context to add.
		return ctrl.Result{}, err
	}

	switch {
	case status.Active > 0:
		logger.Info("Job is still active, requeuing")
		machineImage.Status.Phase = kubernetesupgraderv1.MachineImagePhaseBuilding
		// Already watching Jobs, but force a requeue to limit the maximum time to wait.
		return ctrl.Result{RequeueAfter: imageBuilderJobRequeueDelay}, nil
	case status.Succeeded > 0:
		if id == "" {
			logger.Info("Job succeeded but Image ID is empty, will not requeue")
			//nolint:goerr113 // This is a user facing error.
			return ctrl.Result{}, errors.New(
				"job completed but image id is empty, delete the job to retry",
			)
		}
		logger.Info(fmt.Sprintf("Job succeeded, updating with image id: %s", id))
		machineImage.Spec.ID = id
		machineImage.Status.Ready = true
		machineImage.Status.Phase = kubernetesupgraderv1.MachineImagePhaseCreated
		return ctrl.Result{}, nil
	case status.Failed > 0:
		logger.Info("Job failed, will not requeue")
		machineImage.Status.Phase = kubernetesupgraderv1.MachineImagePhaseFailed
		//nolint:goerr113 // This is a user facing error.
		return ctrl.Result{}, errors.New("job failed, delete the job to retry")
	}

	return ctrl.Result{}, nil
}

func patchMachineImage(
	ctx context.Context,
	patchHelper *patch.Helper,
	machineImage *kubernetesupgraderv1.MachineImage,
) error {
	// Patch the object, ignoring conflicts on the conditions owned by this controller.
	//nolint:wrapcheck // This is generated code.
	return patchHelper.Patch(
		ctx,
		machineImage,
	)
}

// SetupWithManager sets up the controller with the Manager.
func (r *MachineImageReconciler) SetupWithManager(mgr ctrl.Manager) error {
	//nolint:wrapcheck // This is generated code.
	return ctrl.NewControllerManagedBy(mgr).
		For(&kubernetesupgraderv1.MachineImage{}).
		Owns(&batchv1.Job{}).
		Complete(r)
}