cert-manager/pkg/controller/expcertificates/requestmanager/requestmanager_controller.go

/*
Copyright 2020 The Jetstack cert-manager contributors.

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 requestmanager

import (
	"bytes"
	"context"
	"crypto"
	"encoding/pem"
	"fmt"
	"strconv"
	"time"

	"github.com/go-logr/logr"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/informers"
	corelisters "k8s.io/client-go/listers/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"

	apiutil "github.com/jetstack/cert-manager/pkg/api/util"
	cmapi "github.com/jetstack/cert-manager/pkg/apis/certmanager/v1alpha2"
	cmmeta "github.com/jetstack/cert-manager/pkg/apis/meta/v1"
	cmclient "github.com/jetstack/cert-manager/pkg/client/clientset/versioned"
	cminformers "github.com/jetstack/cert-manager/pkg/client/informers/externalversions"
	cmlisters "github.com/jetstack/cert-manager/pkg/client/listers/certmanager/v1alpha2"
	controllerpkg "github.com/jetstack/cert-manager/pkg/controller"
	certificates "github.com/jetstack/cert-manager/pkg/controller/expcertificates"
	"github.com/jetstack/cert-manager/pkg/controller/expcertificates/internal/predicate"
	logf "github.com/jetstack/cert-manager/pkg/logs"
	"github.com/jetstack/cert-manager/pkg/util/pki"
)

const (
	ControllerName = "CertificateRequestManager"
)

var (
	certificateGvk = cmapi.SchemeGroupVersion.WithKind("Certificate")
)

type controller struct {
	certificateLister        cmlisters.CertificateLister
	certificateRequestLister cmlisters.CertificateRequestLister
	secretLister             corelisters.SecretLister
	client                   cmclient.Interface
	recorder                 record.EventRecorder
}

func NewController(
	log logr.Logger,
	client cmclient.Interface,
	factory informers.SharedInformerFactory,
	cmFactory cminformers.SharedInformerFactory,
	recorder record.EventRecorder,
) (*controller, workqueue.RateLimitingInterface, []cache.InformerSynced) {
	// create a queue used to queue up items to be processed
	queue := workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(time.Second*1, time.Second*30), ControllerName)

	// obtain references to all the informers used by this controller
	certificateInformer := cmFactory.Certmanager().V1alpha2().Certificates()
	certificateRequestInformer := cmFactory.Certmanager().V1alpha2().CertificateRequests()
	secretsInformer := factory.Core().V1().Secrets()

	certificateInformer.Informer().AddEventHandler(&controllerpkg.QueuingEventHandler{Queue: queue})
	certificateRequestInformer.Informer().AddEventHandler(&controllerpkg.BlockingEventHandler{
		// Trigger reconciles on changes to any 'owned' CertificateRequest resources
		WorkFunc: certificates.EnqueueCertificatesForResourceUsingPredicates(log, queue, certificateInformer.Lister(), labels.Everything(),
			predicate.ResourceOwnerOf,
		),
	})
	secretsInformer.Informer().AddEventHandler(&controllerpkg.BlockingEventHandler{
		// Trigger reconciles on changes to any 'owned' secret resources
		WorkFunc: certificates.EnqueueCertificatesForResourceUsingPredicates(log, queue, certificateInformer.Lister(), labels.Everything(),
			predicate.ResourceOwnerOf,
		),
	})

	// build a list of InformerSynced functions that will be returned by the Register method.
	// the controller will only begin processing items once all of these informers have synced.
	mustSync := []cache.InformerSynced{
		secretsInformer.Informer().HasSynced,
		certificateRequestInformer.Informer().HasSynced,
		certificateInformer.Informer().HasSynced,
	}

	return &controller{
		certificateLister:        certificateInformer.Lister(),
		certificateRequestLister: certificateRequestInformer.Lister(),
		secretLister:             secretsInformer.Lister(),
		client:                   client,
		recorder:                 recorder,
	}, queue, mustSync
}

/*
* If the `Issuing` condition is `True`:
    * If the `status.nextPrivateKeySecretName` field is not set:
        * Do nothing
    * List all owned CertificateRequest resources, delete all that have a
      'revision' not equal to `status.revision` + 1 (or `1` if
      `status.revision` is not set).
        * If multiple have the same current revision, delete any that do not 'match'
          as per the two verification steps below. If multiple still exist, log an
          event and delete all but one.
    * If no CertificateRequest for the current revision exists:
        Create a CertificateRequest based on the `certificate.spec`.
    * Verify the public key of the certificate request matches the public key
      of the stored `status.nextPrivateKeySecretName`
        * If not, delete the CertificateRequest & log an Event
    * Verify the CSR options match what is requested in `certificate.spec`
        * If not, delete the CertificateRequest & log an Event
* If the `Issuing` condition is `False` or not set:
    * Delete any CertificateRequest resources that do not have a 'revision'
      equal to `status.revision`.
*/

func (c *controller) ProcessItem(ctx context.Context, key string) error {
	log := logf.FromContext(ctx).WithValues("key", key)
	ctx = logf.NewContext(ctx, log)
	namespace, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		log.Error(err, "invalid resource key passed to ProcessItem")
		return nil
	}

	crt, err := c.certificateLister.Certificates(namespace).Get(name)
	if apierrors.IsNotFound(err) {
		log.Error(err, "certificate not found for key")
		return nil
	}
	if err != nil {
		return err
	}

	if !apiutil.CertificateHasCondition(crt, cmapi.CertificateCondition{
		Type:   cmapi.CertificateConditionIssuing,
		Status: cmmeta.ConditionTrue,
	}) {
		return nil
	}

	// Check for and fetch the 'status.nextPrivateKeySecretName' secret
	if crt.Status.NextPrivateKeySecretName == nil {
		log.V(logf.DebugLevel).Info("status.nextPrivateKeySecretName not yet set, waiting for keymanager before processing certificate")
		return nil
	}
	nextPrivateKeySecret, err := c.secretLister.Secrets(crt.Namespace).Get(*crt.Status.NextPrivateKeySecretName)
	if err != nil {
		return err
	}
	if nextPrivateKeySecret.Data == nil || len(nextPrivateKeySecret.Data[corev1.TLSPrivateKeyKey]) == 0 {
		log.V(logf.DebugLevel).Info("Next private key secret does not contain any valid data, waiting for keymanager before processing certificate")
		return nil
	}
	pk, err := pki.DecodePrivateKeyBytes(nextPrivateKeySecret.Data[corev1.TLSPrivateKeyKey])
	if err != nil {
		log.Error(err, "Failed to decode next private key secret data, waiting for keymanager before processing certificate")
		return nil
	}

	// Discover all 'owned' CertificateRequests
	requests, err := certificates.ListCertificateRequestsMatchingPredicates(c.certificateRequestLister.CertificateRequests(crt.Namespace), labels.Everything(), predicate.ResourceOwnedBy(crt))
	if err != nil {
		return err
	}

	currentCertificateRevision := 0
	if crt.Status.Revision != nil {
		currentCertificateRevision = *crt.Status.Revision
	}
	nextRevision := currentCertificateRevision + 1
	var nextRevisionRequests []*cmapi.CertificateRequest
	for _, req := range requests {
		log := logf.WithRelatedResource(log, req)
		if req.Annotations == nil || req.Annotations[cmapi.CertificateRequestRevisionAnnotationKey] == "" {
			log.V(logf.DebugLevel).Info("Deleting CertificateRequest as it does not contain a revision annotation")
			if err := c.client.CertmanagerV1alpha2().CertificateRequests(req.Namespace).Delete(ctx, req.Name, metav1.DeleteOptions{}); err != nil {
				return err
			}
			continue
		}
		reqRevisionStr := req.Annotations[cmapi.CertificateRequestRevisionAnnotationKey]
		reqRevision, err := strconv.ParseInt(reqRevisionStr, 10, 0)
		if err != nil {
			log.V(logf.DebugLevel).Info("Deleting CertificateRequest as it contains an invalid revision annotation")
			if err := c.client.CertmanagerV1alpha2().CertificateRequests(req.Namespace).Delete(ctx, req.Name, metav1.DeleteOptions{}); err != nil {
				return err
			}
			continue
		}

		if reqRevision == int64(nextRevision) {
			nextRevisionRequests = append(nextRevisionRequests, req)
		}
	}

	var remainingRequests []*cmapi.CertificateRequest
	for _, req := range nextRevisionRequests {
		log := logf.WithRelatedResource(log, req)
		violations, err := certificates.RequestMatchesSpec(req, crt.Spec)
		if err != nil {
			log.Error(err, "Failed to check if CertificateRequest matches spec, deleting CertificateRequest")
			if err := c.client.CertmanagerV1alpha2().CertificateRequests(req.Namespace).Delete(ctx, req.Name, metav1.DeleteOptions{}); err != nil {
				return err
			}
			continue
		}
		if len(violations) > 0 {
			log.V(logf.DebugLevel).Info("CertificateRequest does not match requirements on certificate.spec, deleting CertificateRequest", "violations", violations)
			if err := c.client.CertmanagerV1alpha2().CertificateRequests(req.Namespace).Delete(ctx, req.Name, metav1.DeleteOptions{}); err != nil {
				return err
			}
			continue
		}
		x509Req, err := pki.DecodeX509CertificateRequestBytes(req.Spec.CSRPEM)
		if err != nil {
			// this case cannot happen as RequestMatchesSpec would have returned an error too
			return err
		}
		matches, err := pki.PublicKeyMatchesCSR(pk.Public(), x509Req)
		if err != nil {
			return err
		}
		if !matches {
			log.V(logf.DebugLevel).Info("CertificateRequest contains a CSR that does not have the same public key as the stored next private key secret, deleting CertificateRequest")
			if err := c.client.CertmanagerV1alpha2().CertificateRequests(req.Namespace).Delete(ctx, req.Name, metav1.DeleteOptions{}); err != nil {
				return err
			}
			continue
		}
		remainingRequests = append(remainingRequests, req)
	}

	if len(remainingRequests) == 1 {
		// Nothing to do as we've already verified that the CertificateRequest
		// is up to date above.
		return nil
	}

	if len(remainingRequests) > 1 {
		log.Info("Multiple matching CertificateRequest resources exist, delete one of them !!")
		return nil
	}

	return c.createNewCertificateRequest(ctx, crt, pk, nextRevision, nextPrivateKeySecret.Name)
}

func (c *controller) createNewCertificateRequest(ctx context.Context, crt *cmapi.Certificate, pk crypto.Signer, nextRevision int, nextPrivateKeySecretName string) error {
	log := logf.FromContext(ctx)
	x509CSR, err := pki.GenerateCSR(crt)
	if err != nil {
		log.Error(err, "Failed to generate CSR - will not retry")
		return nil
	}
	csrDER, err := pki.EncodeCSR(x509CSR, pk)
	if err != nil {
		return err
	}

	csrPEM := bytes.NewBuffer([]byte{})
	err = pem.Encode(csrPEM, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csrDER})
	if err != nil {
		return err
	}

	cr := &cmapi.CertificateRequest{
		ObjectMeta: metav1.ObjectMeta{
			Namespace:    crt.Namespace,
			GenerateName: crt.Name + "-",
			Annotations: map[string]string{
				cmapi.CertificateRequestRevisionAnnotationKey: strconv.Itoa(nextRevision),
				cmapi.CRPrivateKeyAnnotationKey:               nextPrivateKeySecretName,
			},
			OwnerReferences: []metav1.OwnerReference{*metav1.NewControllerRef(crt, certificateGvk)},
		},
		Spec: cmapi.CertificateRequestSpec{
			Duration:  crt.Spec.Duration,
			IssuerRef: crt.Spec.IssuerRef,
			CSRPEM:    csrPEM.Bytes(),
			IsCA:      crt.Spec.IsCA,
			Usages:    crt.Spec.Usages,
		},
	}

	cr, err = c.client.CertmanagerV1alpha2().CertificateRequests(cr.Namespace).Create(ctx, cr, metav1.CreateOptions{})
	if err != nil {
		return err
	}
	c.recorder.Eventf(crt, corev1.EventTypeNormal, "Requested", "Created new CertificateRequest resource %q", cr.Name)
	if err := c.waitForCertificateRequestToExist(cr.Namespace, cr.Name); err != nil {
		return fmt.Errorf("failed whilst waiting for CertificateRequest to exist - this may indicate an apiserver running slowly. Request will be retried")
	}
	return nil
}

func (c *controller) waitForCertificateRequestToExist(namespace, name string) error {
	return wait.Poll(time.Millisecond*100, time.Second*5, func() (bool, error) {
		_, err := c.certificateRequestLister.CertificateRequests(namespace).Get(name)
		if apierrors.IsNotFound(err) {
			return false, nil
		}
		if err != nil {
			return false, err
		}
		return true, nil
	})
}

// controllerWrapper wraps the `controller` structure to make it implement
// the controllerpkg.queueingController interface
type controllerWrapper struct {
	*controller
}

func (c *controllerWrapper) Register(ctx *controllerpkg.Context) (workqueue.RateLimitingInterface, []cache.InformerSynced, error) {
	// construct a new named logger to be reused throughout the controller
	log := logf.FromContext(ctx.RootContext, ControllerName)

	ctrl, queue, mustSync := NewController(log,
		ctx.CMClient,
		ctx.KubeSharedInformerFactory,
		ctx.SharedInformerFactory,
		ctx.Recorder,
	)
	c.controller = ctrl

	return queue, mustSync, nil
}

func init() {
	controllerpkg.Register(ControllerName, func(ctx *controllerpkg.Context) (controllerpkg.Interface, error) {
		return controllerpkg.NewBuilder(ctx, ControllerName).
			For(&controllerWrapper{}).
			Complete()
	})
}