/
main.go
194 lines (178 loc) · 5.65 KB
/
main.go
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package main
import (
"context"
"crypto/tls"
"encoding/base64"
"flag"
"fmt"
"net/http"
"os"
"time"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/kms"
kmsvaultv1alpha1 "github.com/patoarvizu/kms-vault-operator/api/v1alpha1"
"github.com/radovskyb/watcher"
whhttp "github.com/slok/kubewebhook/pkg/http"
"github.com/slok/kubewebhook/pkg/log"
validatingwh "github.com/slok/kubewebhook/pkg/webhook/validating"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/slok/kubewebhook/pkg/observability/metrics"
)
type webhookCfg struct {
certFile string
keyFile string
addr string
metricsAddr string
}
var cfg = &webhookCfg{}
var cachedCertificate tls.Certificate
func validate(_ context.Context, obj metav1.Object) (bool, validatingwh.ValidatorResult, error) {
awsSession, err := session.NewSession()
if err != nil {
return false, validatingwh.ValidatorResult{}, err
}
svc := kms.New(awsSession)
secret, ok := obj.(*kmsvaultv1alpha1.KMSVaultSecret)
if ok {
for _, s := range secret.Spec.Secrets {
if s.EmptySecret {
continue
}
decoded, err := base64.StdEncoding.DecodeString(s.EncryptedSecret)
if err != nil {
return false, validatingwh.ValidatorResult{
Valid: false,
Message: fmt.Sprintf("Error decoding key %s in KMSVaultSecret %s", s.Key, secret.ObjectMeta.Name),
}, nil
}
_, err = svc.Decrypt(&kms.DecryptInput{CiphertextBlob: decoded, EncryptionContext: getApplicableContext(s.SecretContext, secret.Spec.SecretContext)})
if err != nil {
return false, validatingwh.ValidatorResult{
Valid: false,
Message: fmt.Sprintf("Error decrypting key %s in KMSVaultSecret %s", s.Key, secret.ObjectMeta.Name),
}, nil
}
}
} else {
partial, ok := obj.(*kmsvaultv1alpha1.PartialKMSVaultSecret)
if !ok {
return false, validatingwh.ValidatorResult{}, fmt.Errorf("Object is neither a KMSVaultSecret or a PartialKMSVaultSecret")
}
for _, s := range partial.Spec.Secrets {
if s.EmptySecret {
continue
}
decoded, err := base64.StdEncoding.DecodeString(s.EncryptedSecret)
if err != nil {
return false, validatingwh.ValidatorResult{
Valid: false,
Message: fmt.Sprintf("Error decoding key %s in KMSVaultSecret %s", s.Key, partial.ObjectMeta.Name),
}, nil
}
_, err = svc.Decrypt(&kms.DecryptInput{CiphertextBlob: decoded, EncryptionContext: getApplicableContext(s.SecretContext, partial.Spec.SecretContext)})
if err != nil {
return false, validatingwh.ValidatorResult{
Valid: false,
Message: fmt.Sprintf("Error decrypting key %s in KMSVaultSecret %s", s.Key, partial.ObjectMeta.Name),
}, nil
}
}
}
return false, validatingwh.ValidatorResult{Valid: true}, nil
}
func getApplicableContext(lowerContext map[string]string, higherContext map[string]string) map[string]*string {
if len(lowerContext) > 0 {
return convertContextMap(lowerContext)
} else {
return convertContextMap(higherContext)
}
}
func convertContextMap(context map[string]string) map[string]*string {
m := make(map[string]*string)
for k, v := range context {
m[k] = &v
}
return m
}
func main() {
logger := &log.Std{}
logger.Infof("Starting webhook!")
fl := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
fl.StringVar(&cfg.certFile, "tls-cert-file", "", "TLS certificate file")
fl.StringVar(&cfg.keyFile, "tls-key-file", "", "TLS key file")
fl.StringVar(&cfg.addr, "listen-addr", ":4443", "The address to start the server")
fl.StringVar(&cfg.metricsAddr, "metrics-addr", ":8081", "The address where the Prometheus-style metrics are published")
fl.Parse(os.Args[1:])
w := watcher.New()
defer w.Close()
w.SetMaxEvents(1)
w.FilterOps(watcher.Write)
err := w.Add(cfg.certFile)
if err != nil {
logger.Errorf("Error: %v", err)
}
go func() {
for {
select {
case <-w.Event:
err = cacheCertificate(cfg.certFile, cfg.keyFile)
if err != nil {
logger.Errorf("Error refreshing certificate: %v", err)
os.Exit(1)
}
case <-w.Closed:
logger.Errorf("Certificate file watch closed")
os.Exit(1)
}
}
}()
go w.Start(time.Millisecond * 100)
v := validatingwh.ValidatorFunc(validate)
vhc := validatingwh.WebhookConfig{
Name: "kms-vault-secret-validator",
Obj: &kmsvaultv1alpha1.KMSVaultSecret{},
}
reg := prometheus.NewRegistry()
metricsRec := metrics.NewPrometheus(reg)
wh, err := validatingwh.NewWebhook(vhc, v, nil, metricsRec, logger)
if err != nil {
fmt.Fprintf(os.Stderr, "error creating webhook: %s", err)
os.Exit(1)
}
webhookError := make(chan error)
go func() {
err = cacheCertificate(cfg.certFile, cfg.keyFile)
if err != nil {
logger.Errorf("Error loading certificate: %v", err)
os.Exit(1)
}
server := http.Server{Addr: cfg.addr, Handler: whhttp.MustHandlerFor(wh), TLSConfig: &tls.Config{GetCertificate: getCertificate}}
webhookError <- server.ListenAndServeTLS(cfg.certFile, cfg.keyFile)
}()
metricsError := make(chan error)
promHandler := promhttp.HandlerFor(reg, promhttp.HandlerOpts{})
go func() {
metricsError <- http.ListenAndServe(cfg.metricsAddr, promHandler)
}()
if <-webhookError != nil {
fmt.Fprintf(os.Stderr, "error serving webhook: %s", <-webhookError)
os.Exit(1)
}
if <-metricsError != nil {
fmt.Fprintf(os.Stderr, "error serving metrics: %s", <-metricsError)
os.Exit(1)
}
}
func cacheCertificate(certfile, keyfile string) error {
cert, err := tls.LoadX509KeyPair(certfile, keyfile)
if err != nil {
return err
}
cachedCertificate = cert
return nil
}
func getCertificate(chi *tls.ClientHelloInfo) (*tls.Certificate, error) {
return &cachedCertificate, nil
}