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installer.go
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installer.go
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// Copyright (c) 2018 Intel Corporation
//
// 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 installer
import (
"context"
"io/ioutil"
"strings"
"time"
"github.com/cloudflare/cfssl/csr"
"github.com/golang/glog"
"github.com/pkg/errors"
arv1 "k8s.io/api/admissionregistration/v1"
"k8s.io/api/certificates/v1beta1"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/util/intstr"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
)
var (
clientset kubernetes.Interface
namespace string
prefix string
)
const keyBitLength = 3072
func generateCSR() ([]byte, []byte, error) {
glog.Infof("generating Certificate Signing Request")
serviceName := strings.Join([]string{prefix, "service"}, "-")
certRequest := csr.New()
certRequest.KeyRequest = &csr.KeyRequest{A: "rsa", S: keyBitLength}
certRequest.CN = strings.Join([]string{serviceName, namespace, "svc"}, ".")
certRequest.Hosts = []string{
serviceName,
strings.Join([]string{serviceName, namespace}, "."),
strings.Join([]string{serviceName, namespace, "svc"}, "."),
}
return csr.ParseRequest(certRequest)
}
func getSignedCertificate(request []byte) ([]byte, error) {
csrName := strings.Join([]string{prefix, "csr"}, "-")
csr, err := clientset.CertificatesV1beta1().CertificateSigningRequests().Get(context.TODO(), csrName, metav1.GetOptions{})
if csr != nil || err == nil {
glog.Infof("CSR %s already exists, removing it first", csrName)
clientset.CertificatesV1beta1().CertificateSigningRequests().Delete(context.TODO(), csrName, metav1.DeleteOptions{})
}
glog.Infof("creating new CSR %s", csrName)
/* build Kubernetes CSR object */
csr = &v1beta1.CertificateSigningRequest{}
csr.ObjectMeta.Name = csrName
csr.ObjectMeta.Namespace = namespace
csr.Spec.Request = request
csr.Spec.Groups = []string{"system:authenticated"}
csr.Spec.Usages = []v1beta1.KeyUsage{v1beta1.UsageDigitalSignature, v1beta1.UsageServerAuth, v1beta1.UsageKeyEncipherment}
/* push CSR to Kubernetes API server */
csr, err = clientset.CertificatesV1beta1().CertificateSigningRequests().Create(context.TODO(), csr, metav1.CreateOptions{})
if err != nil {
return nil, errors.Wrap(err, "error creating CSR in Kubernetes API: %s")
}
glog.Infof("CSR pushed to the Kubernetes API")
if csr.Status.Certificate != nil {
glog.Infof("using already issued certificate for CSR %s", csrName)
return csr.Status.Certificate, nil
}
/* approve certificate in K8s API */
csr.ObjectMeta.Name = csrName
csr.ObjectMeta.Namespace = namespace
csr.Status.Conditions = append(csr.Status.Conditions, v1beta1.CertificateSigningRequestCondition{
Type: v1beta1.CertificateApproved,
Reason: "Approved by net-attach-def admission controller installer",
Message: "This CSR was approved by net-attach-def admission controller installer.",
LastUpdateTime: metav1.Now(),
})
_, err = clientset.CertificatesV1beta1().CertificateSigningRequests().UpdateApproval(context.TODO(), csr, metav1.UpdateOptions{})
glog.Infof("certificate approval sent")
if err != nil {
return nil, errors.Wrap(err, "error approving CSR in Kubernetes API")
}
/* wait for the cert to be issued */
glog.Infof("waiting for the signed certificate to be issued...")
start := time.Now()
for range time.Tick(time.Second) {
csr, err = clientset.CertificatesV1beta1().CertificateSigningRequests().Get(context.TODO(), csrName, metav1.GetOptions{})
if err != nil {
return nil, errors.Wrap(err, "error getting signed ceritificate from the API server")
}
if csr.Status.Certificate != nil {
return csr.Status.Certificate, nil
}
if time.Since(start) > 60*time.Second {
break
}
}
return nil, errors.New("error getting certificate from the API server: request timed out - verify that Kubernetes certificate signer is setup, more at https://kubernetes.io/docs/tasks/tls/managing-tls-in-a-cluster/#a-note-to-cluster-administrators")
}
func writeToFile(certificate, key []byte, certFilename, keyFilename string) error {
if err := ioutil.WriteFile("/etc/tls/"+certFilename, certificate, 0400); err != nil {
return err
}
if err := ioutil.WriteFile("/etc/tls/"+keyFilename, key, 0400); err != nil {
return err
}
return nil
}
func createMutatingWebhookConfiguration(certificate []byte, failurePolicyStr string) error {
configName := strings.Join([]string{prefix, "mutating-config"}, "-")
serviceName := strings.Join([]string{prefix, "service"}, "-")
removeMutatingWebhookIfExists(configName)
var failurePolicy arv1.FailurePolicyType
if strings.EqualFold(strings.TrimSpace(failurePolicyStr), "Ignore") {
failurePolicy = arv1.Ignore
} else if strings.EqualFold(strings.TrimSpace(failurePolicyStr), "Fail") {
failurePolicy = arv1.Fail
} else {
return errors.New("unknown failure policy type")
}
sideEffects := arv1.SideEffectClassNone
path := "/mutate"
configuration := &arv1.MutatingWebhookConfiguration{
ObjectMeta: metav1.ObjectMeta{
Name: configName,
Labels: map[string]string{
"app": prefix,
},
},
Webhooks: []arv1.MutatingWebhook{
arv1.MutatingWebhook{
Name: configName + ".k8s.cni.cncf.io",
ClientConfig: arv1.WebhookClientConfig{
CABundle: certificate,
Service: &arv1.ServiceReference{
Namespace: namespace,
Name: serviceName,
Path: &path,
},
},
FailurePolicy: &failurePolicy,
AdmissionReviewVersions: []string{"v1"},
SideEffects: &sideEffects,
Rules: []arv1.RuleWithOperations{
arv1.RuleWithOperations{
Operations: []arv1.OperationType{arv1.Create},
Rule: arv1.Rule{
APIGroups: []string{""},
APIVersions: []string{"v1"},
Resources: []string{"pods"},
},
},
},
},
},
}
_, err := clientset.AdmissionregistrationV1().MutatingWebhookConfigurations().Create(context.TODO(), configuration, metav1.CreateOptions{})
return err
}
func createService() error {
serviceName := strings.Join([]string{prefix, "service"}, "-")
removeServiceIfExists(serviceName)
service := &corev1.Service{
ObjectMeta: metav1.ObjectMeta{
Name: serviceName,
Labels: map[string]string{
"app": prefix,
},
},
Spec: corev1.ServiceSpec{
Ports: []corev1.ServicePort{
corev1.ServicePort{
Port: 443,
TargetPort: intstr.FromInt(8443),
},
},
Selector: map[string]string{
"app": prefix,
},
},
}
_, err := clientset.CoreV1().Services(namespace).Create(context.TODO(), service, metav1.CreateOptions{})
return err
}
func removeServiceIfExists(serviceName string) {
service, err := clientset.CoreV1().Services(namespace).Get(context.TODO(), serviceName, metav1.GetOptions{})
if service != nil && err == nil {
glog.Infof("service %s already exists, removing it first", serviceName)
err := clientset.CoreV1().Services(namespace).Delete(context.TODO(), serviceName, metav1.DeleteOptions{})
if err != nil {
glog.Errorf("error trying to remove service: %s", err)
}
glog.Infof("service %s removed", serviceName)
}
}
func removeMutatingWebhookIfExists(configName string) {
config, err := clientset.AdmissionregistrationV1().MutatingWebhookConfigurations().Get(context.TODO(), configName, metav1.GetOptions{})
if config != nil && err == nil {
glog.Infof("mutating webhook %s already exists, removing it first", configName)
err := clientset.AdmissionregistrationV1().MutatingWebhookConfigurations().Delete(context.TODO(), configName, metav1.DeleteOptions{})
if err != nil {
glog.Errorf("error trying to remove mutating webhook configuration: %s", err)
}
glog.Infof("mutating webhook configuration %s removed", configName)
}
}
func removeSecretIfExists(secretName string) {
secret, err := clientset.CoreV1().Secrets(namespace).Get(context.TODO(), secretName, metav1.GetOptions{})
if secret != nil && err == nil {
glog.Infof("secret %s already exists, removing it first", secretName)
err := clientset.CoreV1().Secrets(namespace).Delete(context.TODO(), secretName, metav1.DeleteOptions{})
if err != nil {
glog.Errorf("error trying to remove secret: %s", err)
}
glog.Infof("secret %s removed", secretName)
}
}
// Install creates resources required by mutating admission webhook
func Install(k8sNamespace, namePrefix, failurePolicy string) {
/* setup Kubernetes API client */
config, err := rest.InClusterConfig()
if err != nil {
glog.Fatalf("error loading Kubernetes in-cluster configuration: %s", err)
}
clientset, err = kubernetes.NewForConfig(config)
if err != nil {
glog.Fatalf("error setting up Kubernetes client: %s", err)
}
namespace = k8sNamespace
prefix = namePrefix
/* generate CSR and private key */
csr, key, err := generateCSR()
if err != nil {
glog.Fatalf("error generating CSR and private key: %s", err)
}
glog.Infof("raw CSR and private key successfully created")
/* obtain signed certificate */
certificate, err := getSignedCertificate(csr)
if err != nil {
glog.Fatalf("error getting signed certificate: %s", err)
}
glog.Infof("signed certificate successfully obtained")
err = writeToFile(certificate, key, "tls.crt", "tls.key")
if err != nil {
glog.Fatalf("error writing certificate and key to files: %s", err)
}
glog.Infof("certificate and key written to files")
/* create webhook configurations */
err = createMutatingWebhookConfiguration(certificate, failurePolicy)
if err != nil {
glog.Fatalf("error creating mutating webhook configuration: %s", err)
}
glog.Infof("mutating webhook configuration successfully created")
/* create service */
err = createService()
if err != nil {
glog.Fatalf("error creating service: %s", err)
}
glog.Infof("service successfully created")
glog.Infof("all resources created successfully")
}