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storage.go
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storage.go
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package storage
import (
"context"
"fmt"
"io/fs"
"regexp"
"strings"
"time"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/certmagic"
"github.com/google/uuid"
"go.uber.org/zap"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/client-go/tools/leaderelection/resourcelock"
)
const (
leaseDuration = 5 * time.Second
leaseRenewInterval = 2 * time.Second
leasePollInterval = 5 * time.Second
leasePrefix = "caddy-lock-"
keyPrefix = "caddy.ingress--"
)
// matchLabels are attached to each resource so that they can be found in the future.
var matchLabels = map[string]string{
"manager": "caddy",
}
// specialChars is a regex that matches all special characters except '-'.
var specialChars = regexp.MustCompile("[^\\da-zA-Z-]+")
// cleanKey strips all special characters that are not supported by kubernetes names and converts them to a '.'.
// sequences like '.*.' are also converted to a single '.'.
func cleanKey(key string, prefix string) string {
return prefix + specialChars.ReplaceAllString(key, ".")
}
// SecretStorage facilitates storing certificates retrieved by certmagic in kubernetes secrets.
type SecretStorage struct {
Namespace string
LeaseId string
kubeClient *kubernetes.Clientset
logger *zap.Logger
}
func init() {
caddy.RegisterModule(SecretStorage{})
}
func (SecretStorage) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "caddy.storage.secret_store",
New: func() caddy.Module { return new(SecretStorage) },
}
}
// Provisions the SecretStorage instance.
func (s *SecretStorage) Provision(ctx caddy.Context) error {
config, _ := clientcmd.BuildConfigFromFlags("", "")
// creates the clientset
clientset, _ := kubernetes.NewForConfig(config)
s.logger = ctx.Logger(s)
s.kubeClient = clientset
if s.LeaseId == "" {
s.LeaseId = uuid.New().String()
}
return nil
}
// CertMagicStorage returns a certmagic storage type to be used by caddy.
func (s *SecretStorage) CertMagicStorage() (certmagic.Storage, error) {
return s, nil
}
// Exists returns true if key exists in fs.
func (s *SecretStorage) Exists(ctx context.Context, key string) bool {
s.logger.Debug("finding secret", zap.String("name", key))
secrets, err := s.kubeClient.CoreV1().Secrets(s.Namespace).List(context.TODO(), metav1.ListOptions{
FieldSelector: fmt.Sprintf("metadata.name=%v", cleanKey(key, keyPrefix)),
})
if err != nil {
return false
}
var found bool
for _, i := range secrets.Items {
if i.ObjectMeta.Name == cleanKey(key, keyPrefix) {
found = true
break
}
}
return found
}
// Store saves value at key. More than certs and keys are stored by certmagic in secrets.
func (s *SecretStorage) Store(ctx context.Context, key string, value []byte) error {
se := corev1.Secret{
ObjectMeta: metav1.ObjectMeta{
Name: cleanKey(key, keyPrefix),
Labels: matchLabels,
},
Data: map[string][]byte{
"value": value,
},
}
var err error
if s.Exists(ctx, key) {
s.logger.Debug("creating secret", zap.String("name", key))
_, err = s.kubeClient.CoreV1().Secrets(s.Namespace).Update(context.TODO(), &se, metav1.UpdateOptions{})
} else {
s.logger.Debug("updating secret", zap.String("name", key))
_, err = s.kubeClient.CoreV1().Secrets(s.Namespace).Create(context.TODO(), &se, metav1.CreateOptions{})
}
if err != nil {
return err
}
return nil
}
// Load retrieves the value at the given key.
func (s *SecretStorage) Load(ctx context.Context, key string) ([]byte, error) {
secret, err := s.kubeClient.CoreV1().Secrets(s.Namespace).Get(context.TODO(), cleanKey(key, keyPrefix), metav1.GetOptions{})
if err != nil {
if errors.IsNotFound(err) {
return nil, fs.ErrNotExist
}
return nil, err
}
s.logger.Debug("loading secret", zap.String("name", key))
return secret.Data["value"], nil
}
// Delete deletes the value at the given key.
func (s *SecretStorage) Delete(ctx context.Context, key string) error {
err := s.kubeClient.CoreV1().Secrets(s.Namespace).Delete(context.TODO(), cleanKey(key, keyPrefix), metav1.DeleteOptions{})
if err != nil {
return err
}
s.logger.Debug("deleting secret", zap.String("name", key))
return nil
}
// List returns all keys that match prefix.
func (s *SecretStorage) List(ctx context.Context, prefix string, recursive bool) ([]string, error) {
var keys []string
s.logger.Debug("listing secrets", zap.String("name", prefix))
secrets, err := s.kubeClient.CoreV1().Secrets(s.Namespace).List(context.TODO(), metav1.ListOptions{
LabelSelector: labels.SelectorFromSet(matchLabels).String(),
})
if err != nil {
return keys, err
}
// TODO :- do we need to handle the recursive flag?
for _, secret := range secrets.Items {
key := secret.ObjectMeta.Name
if strings.HasPrefix(key, cleanKey(prefix, keyPrefix)) {
keys = append(keys, strings.TrimPrefix(key, keyPrefix))
}
}
return keys, err
}
// Stat returns information about key.
func (s *SecretStorage) Stat(ctx context.Context, key string) (certmagic.KeyInfo, error) {
secret, err := s.kubeClient.CoreV1().Secrets(s.Namespace).Get(context.TODO(), cleanKey(key, keyPrefix), metav1.GetOptions{})
if err != nil {
return certmagic.KeyInfo{}, err
}
s.logger.Debug("stats secret", zap.String("name", key))
return certmagic.KeyInfo{
Key: key,
Modified: secret.GetCreationTimestamp().UTC(),
Size: int64(len(secret.Data["value"])),
IsTerminal: false,
}, nil
}
func (s *SecretStorage) Lock(ctx context.Context, key string) error {
for {
_, err := s.tryAcquireOrRenew(ctx, cleanKey(key, leasePrefix), false)
if err == nil {
go s.keepLockUpdated(ctx, cleanKey(key, leasePrefix))
return nil
}
select {
case <-time.After(leasePollInterval):
case <-ctx.Done():
return ctx.Err()
}
}
}
func (s *SecretStorage) keepLockUpdated(ctx context.Context, key string) {
for {
time.Sleep(leaseRenewInterval)
done, err := s.tryAcquireOrRenew(ctx, key, true)
if err != nil {
return
}
if done {
return
}
}
}
func (s *SecretStorage) tryAcquireOrRenew(ctx context.Context, key string, shouldExist bool) (bool, error) {
now := metav1.Now()
lock := resourcelock.LeaseLock{
LeaseMeta: metav1.ObjectMeta{
Name: key,
Namespace: s.Namespace,
},
Client: s.kubeClient.CoordinationV1(),
LockConfig: resourcelock.ResourceLockConfig{
Identity: s.LeaseId,
},
}
ler := resourcelock.LeaderElectionRecord{
HolderIdentity: lock.Identity(),
LeaseDurationSeconds: 5,
AcquireTime: now,
RenewTime: now,
}
currLer, _, err := lock.Get(ctx)
// 1. obtain or create the ElectionRecord
if err != nil {
if !errors.IsNotFound(err) {
return true, err
}
if shouldExist {
return true, nil // Lock has been released
}
if err = lock.Create(ctx, ler); err != nil {
return true, err
}
return false, nil
}
// 2. Record obtained, check the Identity & Time
if currLer.HolderIdentity != "" &&
currLer.RenewTime.Add(leaseDuration).After(now.Time) &&
currLer.HolderIdentity != lock.Identity() {
return true, fmt.Errorf("lock is held by %v and has not yet expired", currLer.HolderIdentity)
}
// 3. We're going to try to update the existing one
if currLer.HolderIdentity == lock.Identity() {
ler.AcquireTime = currLer.AcquireTime
ler.LeaderTransitions = currLer.LeaderTransitions
} else {
ler.LeaderTransitions = currLer.LeaderTransitions + 1
}
if err = lock.Update(ctx, ler); err != nil {
return true, fmt.Errorf("failed to update lock: %v", err)
}
return false, nil
}
func (s *SecretStorage) Unlock(ctx context.Context, key string) error {
err := s.kubeClient.CoordinationV1().Leases(s.Namespace).Delete(context.TODO(), cleanKey(key, leasePrefix), metav1.DeleteOptions{})
return err
}