Add certwatcher to webhook server

Signed-off-by: Grant Griffiths <grant@portworx.com>

pkg/validation-webhook/webhook_test.go

@@ -0,0 +1,169 @@
+package webhook
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"math/big"
+	"net"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestWebhookCertReload(t *testing.T) {
+	// Initialize test space
+	tmpDir := os.TempDir() + "/webhook-cert-tests"
+	certFile = tmpDir + "/tls.crt"
+	keyFile = tmpDir + "/tls.key"
+	port = 30443
+	err := os.Mkdir(tmpDir, 0777)
+	if err != nil && err != os.ErrExist {
+		t.Errorf("unexpected error occurred while creating tmp dir: %v", err)
+	}
+	defer func() {
+		err := os.RemoveAll(tmpDir)
+		if err != nil {
+			t.Errorf("unexpected error occurred while deleting certs: %v", err)
+		}
+	}()
+	generateTestCertKeyPair(t, certFile, keyFile)
+
+	// Start test server
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	cw, err := NewCertWatcher(certFile, keyFile)
+	if err != nil {
+		t.Errorf("failed to initialize new cert watcher: %v", err)
+	}
+	tlsConfig := &tls.Config{
+		GetCertificate: cw.GetCertificate,
+	}
+	go func() {
+		if err := startServer(ctx, tlsConfig, cw); err != nil {
+			panic(err)
+		}
+	}()
+	time.Sleep(250 * time.Millisecond) // Give some time for watcher to start
+
+	// TC: Original cert should not change with no file changes
+	originalCert, err := tlsConfig.GetCertificate(nil)
+	if err != nil {
+		t.Errorf("unexpected error occurred while getting cert: %v", err)
+	}
+	originalCertStr := string(originalCert.Certificate[0])
+	originalKey := originalCert.PrivateKey.(*rsa.PrivateKey)
+
+	newCert, err := tlsConfig.GetCertificate(nil) // get certificate again
+	if err != nil {
+		t.Errorf("unexpected error occurred while getting  newcert: %v", err)
+	}
+	if string(newCert.Certificate[0]) != originalCertStr {
+		t.Error("new cert was updated when it should not have been")
+	}
+	newKey := newCert.PrivateKey.(*rsa.PrivateKey)
+	if !newKey.Equal(originalKey) {
+		t.Error("new key was updated when it should not have been")
+	}
+
+	// TC: Certificate should consistently change with a file change
+	for i := 0; i < 5; i++ {
+		// Generate new key/cert
+		generateTestCertKeyPair(t, certFile, keyFile)
+
+		// Wait for certwatcher to update
+		time.Sleep(250 * time.Millisecond)
+		newCert, err = tlsConfig.GetCertificate(nil)
+		if err != nil {
+			t.Errorf("unexpected error occurred while getting  newcert: %v", err)
+		}
+		if string(newCert.Certificate[0]) == originalCertStr {
+			t.Errorf("new cert was not updated")
+		}
+
+		newKey = newCert.PrivateKey.(*rsa.PrivateKey)
+		if newKey.Equal(originalKey) {
+			t.Error("new key was not updated")
+		}
+
+		originalCertStr = string(newCert.Certificate[0])
+		originalKey = newKey
+	}
+}
+
+// generateTestCertKeyPair generates a new random test key/crt and writes it to tmpDir
+// based on https://golang.org/src/crypto/tls/generate_cert.go
+func generateTestCertKeyPair(t *testing.T, certPath, keyPath string) error {
+	notBefore := time.Now()
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		return fmt.Errorf("Failed to generate serial number: %v", err)
+	}
+
+	var priv interface{}
+	priv, err = rsa.GenerateKey(rand.Reader, 4096)
+	if err != nil {
+		return fmt.Errorf("Failed to generate key: %v", err)
+	}
+	keyUsage := x509.KeyUsageDigitalSignature
+	if _, isRSA := priv.(*rsa.PrivateKey); isRSA {
+		keyUsage |= x509.KeyUsageKeyEncipherment
+	}
+	randomOrganizationStr := time.Now().String()
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{randomOrganizationStr},
+		},
+		NotBefore: notBefore,
+		NotAfter:  time.Now().Add(1 * time.Hour),
+
+		KeyUsage:              keyUsage,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		IPAddresses:           []net.IP{net.ParseIP("127.0.0.1")},
+		DNSNames:              []string{"127.0.0.1"},
+	}
+
+	rk := priv.(*rsa.PrivateKey)
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &rk.PublicKey, priv)
+	if err != nil {
+		return fmt.Errorf("Failed to create certificate: %v", err)
+	}
+
+	certOut, err := os.Create(certPath)
+	if err != nil {
+		return fmt.Errorf("Failed to open tls.crt for writing: %v", err)
+	}
+	if err := pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
+		return fmt.Errorf("Failed to write data to tls.crt: %v", err)
+	}
+	if err := certOut.Close(); err != nil {
+		return fmt.Errorf("Error closing tls.crt: %v", err)
+	}
+	fmt.Printf("wrote new cert: %s\n", certPath)
+
+	keyOut, err := os.OpenFile(keyPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		return fmt.Errorf("Failed to open tls.key for writing: %v", err)
+	}
+	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
+	if err != nil {
+		return fmt.Errorf("Unable to marshal private key: %v", err)
+	}
+	if err := pem.Encode(keyOut, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes}); err != nil {
+		return fmt.Errorf("Failed to write data to tls.key: %v", err)
+	}
+	if err := keyOut.Close(); err != nil {
+		return fmt.Errorf("Error closing tls.key: %v", err)
+	}
+	fmt.Printf("wrote new key: %s\n", keyPath)
+
+	return nil
+}