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k8s.go
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k8s.go
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// Package k8s implements helper functions to get certificates from Kubernetes secret
package k8s
import (
"context"
"github.com/rs/zerolog/log"
"k8s.io/client-go/kubernetes"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"github.com/flomesh-io/fsm/pkg/certificate"
"github.com/flomesh-io/fsm/pkg/constants"
"github.com/flomesh-io/fsm/pkg/errcode"
"github.com/flomesh-io/fsm/pkg/version"
)
// GetCertFromKubernetes is a helper function that loads a certificate from a Kubernetes secret
func GetCertFromKubernetes(ns string, secretName string, kubeClient kubernetes.Interface) (*certificate.Certificate, error) {
certSecret, err := kubeClient.CoreV1().Secrets(ns).Get(context.Background(), secretName, metav1.GetOptions{})
if err != nil {
// TODO(#3962): metric might not be scraped before process restart resulting from this error
log.Error().Str(errcode.Kind, errcode.GetErrCodeWithMetric(errcode.ErrFetchingCertSecret)).
Msgf("Could not retrieve certificate secret %q from namespace %q", secretName, ns)
return nil, certificate.ErrSecretNotFound
}
pemCert, ok := certSecret.Data[constants.KubernetesOpaqueSecretCAKey]
if !ok {
// TODO(#3962): metric might not be scraped before process restart resulting from this error
log.Error().Err(certificate.ErrInvalidCertSecret).Str(errcode.Kind, errcode.GetErrCodeWithMetric(errcode.ErrObtainingCertFromSecret)).
Msgf("Opaque k8s secret %s/%s does not have required field %q", ns, secretName, constants.KubernetesOpaqueSecretCAKey)
return nil, certificate.ErrInvalidCertSecret
}
pemKey, ok := certSecret.Data[constants.KubernetesOpaqueSecretRootPrivateKeyKey]
if !ok {
// TODO(#3962): metric might not be scraped before process restart resulting from this error
log.Error().Err(certificate.ErrInvalidCertSecret).Str(errcode.Kind, errcode.GetErrCodeWithMetric(errcode.ErrObtainingPrivateKeyFromSecret)).
Msgf("Opaque k8s secret %s/%s does not have required field %q", ns, secretName, constants.KubernetesOpaqueSecretRootPrivateKeyKey)
return nil, certificate.ErrInvalidCertSecret
}
cert, err := certificate.NewFromPEM(pemCert, pemKey)
if err != nil {
log.Error().Err(err).Msg("Failed to create new Certificate from PEM")
return nil, err
}
return cert, nil
}
// GetCertificateFromSecret is a helper function that ensures creation and synchronization of a certificate
// using Kubernetes Secrets backend and API atomicity.
func GetCertificateFromSecret(ns string, secretName string, cert *certificate.Certificate, kubeClient kubernetes.Interface) (*certificate.Certificate, error) {
// Attempt to create it in Kubernetes. When multiple agents attempt to create, only one of them will succeed.
// All others will get "AlreadyExists" error back.
secretData := map[string][]byte{
constants.KubernetesOpaqueSecretCAKey: cert.GetCertificateChain(),
constants.KubernetesOpaqueSecretRootPrivateKeyKey: cert.GetPrivateKey(),
}
secret := &corev1.Secret{
ObjectMeta: metav1.ObjectMeta{
Name: secretName,
Namespace: ns,
Labels: map[string]string{
constants.FSMAppNameLabelKey: constants.FSMAppNameLabelValue,
constants.FSMAppVersionLabelKey: version.Version,
},
},
Data: secretData,
}
if _, err := kubeClient.CoreV1().Secrets(ns).Create(context.TODO(), secret, metav1.CreateOptions{}); err == nil {
log.Info().Msgf("Secret %s/%s created in kubernetes", ns, secretName)
} else if apierrors.IsAlreadyExists(err) {
log.Info().Msgf("Secret %s/%s already exists in kubernetes, loading.", ns, secretName)
} else {
// TODO(#3962): metric might not be scraped before process restart resulting from this error
log.Error().Err(err).Str(errcode.Kind, errcode.GetErrCodeWithMetric(errcode.ErrCreatingCertSecret)).
Msgf("Error creating/retrieving certificate secret %s/%s", ns, secretName)
return nil, err
}
// For simplicity, we will load the certificate for all of them, this way the instance which created it
// and the ones that didn't share the same code.
cert, err := GetCertFromKubernetes(ns, secretName, kubeClient)
if err != nil {
log.Error().Err(err).Msg("Failed to fetch certificate from Kubernetes")
return nil, err
}
return cert, nil
}