cert-manager/pkg/controller/certificatesigningrequests/controller.go

/*
Copyright 2021 The cert-manager 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 certificatesigningrequests

import (
	"context"
	"fmt"

	"github.com/go-logr/logr"
	certificatesv1 "k8s.io/api/certificates/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime/schema"
	authzclient "k8s.io/client-go/kubernetes/typed/authorization/v1"
	certificatesclient "k8s.io/client-go/kubernetes/typed/certificates/v1"
	certificateslisters "k8s.io/client-go/listers/certificates/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"
	"k8s.io/utils/clock"

	cmapi "github.com/cert-manager/cert-manager/pkg/apis/certmanager/v1"
	controllerpkg "github.com/cert-manager/cert-manager/pkg/controller"
	"github.com/cert-manager/cert-manager/pkg/issuer"
	logf "github.com/cert-manager/cert-manager/pkg/logs"
)

var keyFunc = controllerpkg.KeyFunc

// Signer is an implementation of a Kubernetes CertificateSigningRequest
// signer, backed by a cert-manager Issuer.
type Signer interface {
	Sign(context.Context, *certificatesv1.CertificateSigningRequest, cmapi.GenericIssuer) error
}

// Signer Contractor builds a Signer instance using the given controller
// context.
type SignerConstructor func(*controllerpkg.Context) Signer

// Controller is a base Kubernetes CertificateSigningRequest controller. It is
// responsible for orchestrating and performing shared operations that all
// CertificateSigningRequest controllers do, before passing the
// CertificateSigningRequest to a Singer implementation who instantiated this
// controller.
type Controller struct {
	helper issuer.Helper

	// clientset used to update CertificateSigningRequest API resources
	certClient certificatesclient.CertificateSigningRequestInterface
	csrLister  certificateslisters.CertificateSigningRequestLister
	sarClient  authzclient.SubjectAccessReviewInterface

	// fieldManager is the manager name used for the Apply operations.
	fieldManager string

	queue workqueue.RateLimitingInterface

	// logger to be used by this controller
	log logr.Logger

	// used to record Events about resources to the API
	recorder record.EventRecorder

	// Signer to call sign function
	signerConstructor SignerConstructor
	signer            Signer

	// the signer kind to react to when a certificate signing request is synced
	signerType string

	// extraInformerResources are the set of resources which should cause
	// reconciles if owned by a CertifcateRequest.
	extraInformerResources []schema.GroupVersionResource

	// used for testing
	clock clock.Clock
}

// New will construct a new certificatesigningrequest controller using the
// given Signer implementation.
// Note: the extraInformers passed here will be 'waited' for when starting to
// ensure their corresponding listers have synced.
// An event handler will then be set on these informers that automatically
// resyncs CertificateSigningRequest resources that 'own' the objects in the
// informer.
// It's the callers responsibility to ensure the Run function on the informer
// is called in order to start the reflector. This is handled automatically
// when the informer factory's Start method is called, if the given informer
// was obtained using a SharedInformerFactory.
func New(signerType string, signerConstructor SignerConstructor, extraInformerResources ...schema.GroupVersionResource) *Controller {
	return &Controller{
		signerType:             signerType,
		signerConstructor:      signerConstructor,
		extraInformerResources: extraInformerResources,
	}
}

func (c *Controller) Register(ctx *controllerpkg.Context) (workqueue.RateLimitingInterface, []cache.InformerSynced, error) {
	componentName := "certificatesigningrequests-" + c.signerType

	// construct a new named logger to be reused throughout the controller
	c.log = logf.FromContext(ctx.RootContext, componentName)

	// create a queue used to queue up items to be processed
	c.queue = workqueue.NewNamedRateLimitingQueue(controllerpkg.DefaultItemBasedRateLimiter(), componentName)

	kubeClient := ctx.Client
	c.sarClient = kubeClient.AuthorizationV1().SubjectAccessReviews()

	issuerInformer := ctx.SharedInformerFactory.Certmanager().V1().Issuers()

	// obtain references to all the informers used by this controller
	csrInformer := ctx.KubeSharedInformerFactory.Certificates().V1().CertificateSigningRequests()

	// 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{
		csrInformer.Informer().HasSynced,
		issuerInformer.Informer().HasSynced,
	}

	// Ensure we also catch all extra informers for this
	// CertificateSigningRequest controller instance.
	var extraInformers []cache.SharedIndexInformer
	for _, i := range c.extraInformerResources {
		// TODO (joshvanl): currently we only have an extra informer for
		// cert-manager Orders. If extended to other informer factory sets, add a
		// switch statement here for the group so that the correct shared informer
		// can be selected.
		extraInformer, err := ctx.SharedInformerFactory.ForResource(i)
		if err != nil {
			return nil, nil, fmt.Errorf("failed to get extra informer for %v: %w", i, err)
		}
		extraInformers = append(extraInformers, extraInformer.Informer())
		mustSync = append(mustSync, extraInformer.Informer().HasSynced)
	}

	// if scoped to a single namespace
	// if we are running in non-namespaced mode (i.e. --namespace=""), we also
	// register event handlers and obtain a lister for clusterissuers.
	clusterIssuerInformer := ctx.SharedInformerFactory.Certmanager().V1().ClusterIssuers()
	if ctx.Namespace == "" {
		// register handler function for clusterissuer resources
		clusterIssuerInformer.Informer().AddEventHandler(&controllerpkg.BlockingEventHandler{WorkFunc: c.handleGenericIssuer})
		mustSync = append(mustSync, clusterIssuerInformer.Informer().HasSynced)
	}

	// set all the references to the listers for used by the Sync function
	c.csrLister = csrInformer.Lister()

	// register handler functions
	csrInformer.Informer().AddEventHandler(&controllerpkg.QueuingEventHandler{Queue: c.queue})
	issuerInformer.Informer().AddEventHandler(&controllerpkg.BlockingEventHandler{WorkFunc: c.handleGenericIssuer})

	// Ensure we catch extra informers that are owned by certificate signing requests
	for _, i := range extraInformers {
		i.AddEventHandler(&controllerpkg.BlockingEventHandler{
			WorkFunc: controllerpkg.HandleOwnedResourceNamespacedFunc(c.log, c.queue,
				schema.GroupVersionKind{Version: "v1", Group: "certificates.k8s.io", Kind: "CertificateSigningRequest"},
				func(_, name string) (interface{}, error) {
					return c.csrLister.Get(name)
				}),
		})
	}

	// create an issuer helper for reading generic issuers
	c.helper = issuer.NewHelper(issuerInformer.Lister(), clusterIssuerInformer.Lister())

	c.clock = ctx.Clock
	// recorder records events about resources to the Kubernetes api
	c.recorder = ctx.Recorder
	c.certClient = kubeClient.CertificatesV1().CertificateSigningRequests()
	c.fieldManager = ctx.FieldManager

	// Construct the signer implementation with the built component context.
	c.signer = c.signerConstructor(ctx)

	c.log.V(logf.DebugLevel).Info("new certificate signing request controller registered",
		"type", c.signerType)

	return c.queue, mustSync, nil
}

func (c *Controller) ProcessItem(ctx context.Context, key string) error {
	log := logf.FromContext(ctx)
	dbg := log.V(logf.DebugLevel)

	_, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		log.Error(err, "invalid resource key")
		return nil
	}

	csr, err := c.csrLister.Get(name)
	if apierrors.IsNotFound(err) {
		dbg.Info("certificate signing request in work queue no longer exists", "error", err.Error())
		return nil
	}

	if err != nil {
		return err
	}

	ctx = logf.NewContext(ctx, logf.WithResource(log, csr))
	return c.Sync(ctx, csr)
}