validation: run skipper in validation mode inside webhook

We leave webhook binary for backward combitability but use skipper
in validation mode everywhere as source of truth

Signed-off-by: Mustafa Abdelrahman <[email protected]>

Author: MustafaSaber

cmd/webhook/main.go

@@ -1,19 +1,12 @@
 package main
 
 import (
-	"context"
 	"flag"
-	"net/http"
 	"os"
-	"os/signal"
-	"syscall"
-	"time"
 
-	"github.com/zalando/skipper/dataclients/kubernetes/admission"
+	"github.com/zalando/skipper"
 
-	"github.com/prometheus/client_golang/prometheus/promhttp"
 	log "github.com/sirupsen/logrus"
-	"github.com/zalando/skipper/dataclients/kubernetes/definitions"
 )
 
 const (
@@ -35,16 +28,6 @@ func (c *config) parse() {
 	flag.StringVar(&c.address, "address", defaultHTTPSAddress, "The address to listen on")
 	flag.Parse()
 
-	if (c.certFile != "" || c.keyFile != "") && !(c.certFile != "" && c.keyFile != "") {
-		log.Fatal("Config parse error: both of TLS cert & key must be provided or neither (for testing )")
-		return
-	}
-
-	// support non-HTTPS for local testing
-	if (c.certFile == "" && c.keyFile == "") && c.address == defaultHTTPSAddress {
-		c.address = defaultHTTPAddress
-	}
-
 	if c.debug {
 		log.SetLevel(log.DebugLevel)
 	}
@@ -54,62 +37,17 @@ func main() {
 	var cfg = &config{}
 	cfg.parse()
 
-	rgAdmitter := &admission.RouteGroupAdmitter{
-		RouteGroupValidator: &definitions.RouteGroupValidator{
-			EnableAdvancedValidation: false, // can't start advanced validation in the webhook binary
-		},
-	}
-	ingressAdmitter := &admission.IngressAdmitter{
-		IngressValidator: &definitions.IngressV1Validator{
-			EnableAdvancedValidation: false, // can't start advanced validation in the webhook binary
-		},
-	}
-	handler := http.NewServeMux()
-	handler.Handle("/routegroups", admission.Handler(rgAdmitter))
-	handler.Handle("/ingresses", admission.Handler(ingressAdmitter))
-	handler.Handle("/metrics", promhttp.Handler())
-	handler.HandleFunc("/healthz", healthCheck)
-
-	// One can use generate_cert.go in https://golang.org/pkg/crypto/tls
-	// to generate cert.pem and key.pem.
-	serve(cfg, handler)
-}
-
-func healthCheck(writer http.ResponseWriter, _ *http.Request) {
-	writer.WriteHeader(http.StatusOK)
-	if _, err := writer.Write([]byte("ok")); err != nil {
-		log.Errorf("Failed to write health check: %v", err)
-	}
-
-}
-
-func serve(cfg *config, handler http.Handler) {
-	server := &http.Server{
-		Addr:              cfg.address,
-		Handler:           handler,
-		ReadTimeout:       1 * time.Minute,
-		ReadHeaderTimeout: 1 * time.Minute,
+	skpOptions := skipper.Options{
+		ValidationWebhookEnabled:  true,
+		ValidationWebhookCertFile: cfg.certFile,
+		ValidationWebhookKeyFile:  cfg.keyFile,
+		ValidationWebhookAddress:  cfg.address,
+		EnableAdvancedValidation:  false,
 	}
 
-	log.Infof("Starting server on %s", cfg.address)
-
-	sig := make(chan os.Signal, 1)
-	signal.Notify(sig, syscall.SIGTERM)
-	go func() {
-		<-sig
-		log.Info("Shutting down...")
-		server.Shutdown(context.Background())
-	}()
-
-	var err error
-	if cfg.certFile != "" && cfg.keyFile != "" {
-		err = server.ListenAndServeTLS(cfg.certFile, cfg.keyFile)
-	} else {
-		// support non-HTTPS for local testing
-		err = server.ListenAndServe()
+	if err := skipper.Run(skpOptions); err != nil {
+		log.Fatalf("Failed to start skipper binary in validation mode %v", err)
+		return
 	}
 
-	if err != nil && err != http.ErrServerClosed {
-		log.Fatalf("Failed to listen: %v", err)
-	}
 }

config/config.go

@@ -24,6 +24,7 @@ import (
 	"github.com/zalando/skipper/otel"
 	"github.com/zalando/skipper/proxy"
 	"github.com/zalando/skipper/swarm"
+	"github.com/zalando/skipper/validation"
 )
 
 type Config struct {
@@ -543,7 +544,7 @@ func NewConfig() *Config {
 	flag.BoolVar(&cfg.Oauth2GrantInsecure, "oauth2-grant-insecure", false, "omits Secure attribute of the token cookie and uses http scheme for callback url")
 	flag.DurationVar(&cfg.WebhookTimeout, "webhook-timeout", 2*time.Second, "sets the webhook request timeout duration")
 	flag.BoolVar(&cfg.ValidationWebhookEnabled, "validation-webhook-enabled", false, "enables validation webhook for incoming requests")
-	flag.StringVar(&cfg.ValidationWebhookAddress, "validation-webhook-address", ":9000", "address of the validation webhook service")
+	flag.StringVar(&cfg.ValidationWebhookAddress, "validation-webhook-address", validation.DefaultHTTPSAddress, "address of the validation webhook service")
 	flag.StringVar(&cfg.ValidationWebhookCertFile, "validation-webhook-cert-file", "", "path to the certificate file for the validation webhook")
 	flag.StringVar(&cfg.ValidationWebhookKeyFile, "validation-webhook-key-file", "", "path to the key file for the validation webhook")
 	flag.BoolVar(&cfg.EnableAdvancedValidation, "enable-advanced-validation", false, "enables advanced validation logic for Kubernetes resources")

validation/validation.go

@@ -19,19 +19,27 @@ import (
 )
 
 const (
-	readTimeout       = time.Minute
-	readHeaderTimeout = time.Minute
+	readTimeout         = time.Minute
+	readHeaderTimeout   = time.Minute
+	DefaultHTTPSAddress = ":9443"
+	DefaultHTTPAddress  = ":9080"
 )
 
 // StartValidation launches the validation webhook server and keeps serving until the
 // returned listener encounters an unrecoverable error, or the process shuts down.
 func StartValidation(address, certFile, keyFile string, enableAdvancedValidation bool, filterRegistry filters.Registry, predicateSpecs []routing.PredicateSpec, mtr metrics.Metrics) error {
-	if certFile == "" || keyFile == "" {
-		err := errors.New("validation webhook requires TLS: cert file or key file not provided")
+
+	if (certFile != "" || keyFile != "") && !(certFile != "" && keyFile != "") {
+		err := errors.New("config parse error: both of TLS cert & key must be provided or neither (for testing)")
 		log.Fatal(err)
 		return err
 	}
 
+	// support non-HTTPS for local testing
+	if (certFile == "" && keyFile == "") && address != DefaultHTTPAddress {
+		address = DefaultHTTPAddress
+	}
+
 	handler := newValidationHandler(enableAdvancedValidation, filterRegistry, predicateSpecs, mtr)
 
 	server := &http.Server{
@@ -53,8 +61,13 @@ func StartValidation(address, certFile, keyFile string, enableAdvancedValidation
 			return
 		}
 	}()
-
-	err := server.ListenAndServeTLS(certFile, keyFile)
+	var err error
+	if certFile != "" && keyFile != "" {
+		err = server.ListenAndServeTLS(certFile, keyFile)
+	} else {
+		// support non-HTTPS for local testing
+		err = server.ListenAndServe()
+	}
 
 	if err != nil && !errors.Is(err, http.ErrServerClosed) {
 		log.Fatalf("Failed to listen: %v", err)