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package k8s
import (
"context"
"encoding/json"
"errors"
"expvar"
"fmt"
"os"
"path/filepath"
"time"
"golang.org/x/oauth2"
v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"
)
const secretValue = "oauth2-token"
var (
tokenRefreshCount = expvar.NewInt("gauge_xesite_k8s_token_refresh_count")
ErrSecretValueDoesntExist = errors.New("internal: can't find oauth2-token in secret")
)
type tokenSource struct {
secretName string
namespace string
base oauth2.TokenSource
clientSet kubernetes.Interface
}
func (kts *tokenSource) Token() (tok *oauth2.Token, err error) {
tok, _ = loadTokenFromK8s(context.Background(), kts.clientSet, kts.namespace, kts.secretName)
if tok != nil && tok.Expiry.After(time.Now()) {
return tok, nil
}
if tok, err = kts.base.Token(); err != nil {
return nil, err
}
tokenRefreshCount.Add(1)
if err := kts.saveToken(tok); err != nil {
return nil, err
}
return tok, err
}
func (kts *tokenSource) saveToken(tok *oauth2.Token) error {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
sec, err := kts.clientSet.CoreV1().Secrets(kts.namespace).Get(ctx, kts.secretName, v1.GetOptions{})
if err != nil {
return fmt.Errorf("can't get secret %s::%s: %w", kts.namespace, kts.secretName, err)
}
data, err := json.Marshal(tok)
if err != nil {
return fmt.Errorf("can't marshal json: %w", err)
}
sec.Data[secretValue] = data
if _, err := kts.clientSet.CoreV1().Secrets(kts.namespace).Update(ctx, sec, v1.UpdateOptions{}); err != nil {
return fmt.Errorf("can't update secret %s::%s: %w", kts.namespace, kts.secretName, err)
}
return nil
}
func loadTokenFromK8s(ctx context.Context, cs kubernetes.Interface, ns, secretName string) (*oauth2.Token, error) {
sec, err := cs.CoreV1().Secrets(ns).Get(ctx, secretName, v1.GetOptions{})
if err != nil {
return nil, fmt.Errorf("can't get secret %s::%s: %w", ns, secretName, err)
}
data, ok := sec.Data[secretValue]
if !ok {
return nil, ErrSecretValueDoesntExist
}
var tok oauth2.Token
if err := json.Unmarshal(data, &tok); err != nil {
return nil, fmt.Errorf("can't unmarshal oauth2-token in %s::%s: %w", ns, secretName, err)
}
return &tok, nil
}
func TokenSource(namespace string, secretName string, config *oauth2.Config) (oauth2.TokenSource, error) {
cs, err := getClientSet()
if err != nil {
return nil, fmt.Errorf("can't get client set: %w", err)
}
tok, err := loadTokenFromK8s(context.Background(), cs, namespace, secretName)
if err != nil {
return nil, err
}
orig := config.TokenSource(context.Background(), tok)
return oauth2.ReuseTokenSource(nil, &tokenSource{
secretName: secretName,
namespace: namespace,
base: orig,
clientSet: cs,
}), nil
}
func getClientSet() (kubernetes.Interface, error) {
config, err := rest.InClusterConfig()
if err != nil {
config, err = clientcmd.BuildConfigFromFlags("", filepath.Join(os.Getenv("HOME"), ".kube", "config"))
if err != nil {
return nil, err
}
}
clientSet, err := kubernetes.NewForConfig(config)
if err != nil {
return nil, err
}
return clientSet, nil
}
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