Add --tls-sni-cert-key to the apiserver for SNI support

cmd/kubelet/app/server.go

@@ -502,9 +502,19 @@ func InitializeTLS(kc *componentconfig.KubeletConfiguration) (*server.TLSOptions
 		kc.TLSCertFile = path.Join(kc.CertDirectory, "kubelet.crt")
 		kc.TLSPrivateKeyFile = path.Join(kc.CertDirectory, "kubelet.key")
 		if !certutil.CanReadCertOrKey(kc.TLSCertFile, kc.TLSPrivateKeyFile) {
-			if err := certutil.GenerateSelfSignedCert(nodeutil.GetHostname(kc.HostnameOverride), kc.TLSCertFile, kc.TLSPrivateKeyFile, nil, nil); err != nil {
+			cert, key, err := certutil.GenerateSelfSignedCertKey(nodeutil.GetHostname(kc.HostnameOverride), nil, nil)
+			if err != nil {
 				return nil, fmt.Errorf("unable to generate self signed cert: %v", err)
 			}
+
+			if err := certutil.WriteCert(kc.TLSCertFile, cert); err != nil {
+				return nil, err
+			}
+
+			if err := certutil.WriteKey(kc.TLSPrivateKeyFile, key); err != nil {
+				return nil, err
+			}
+
 			glog.V(4).Infof("Using self-signed cert (%s, %s)", kc.TLSCertFile, kc.TLSPrivateKeyFile)
 		}
 	}

hack/verify-flags/known-flags.txt

@@ -555,6 +555,7 @@ tls-ca-file
 tls-cert-file
 tls-private-key-file
 to-version
+tls-sni-cert-key
 token-auth-file
 ttl-keys-prefix
 ttl-secs

pkg/genericapiserver/config.go

@@ -110,7 +110,7 @@ type Config struct {
 	// same value for this field. (Numbers > 1 currently untested.)
 	MasterCount int
 
-	SecureServingInfo   *ServingInfo
+	SecureServingInfo   *SecureServingInfo
 	InsecureServingInfo *ServingInfo
 
 	// The port on PublicAddress where a read-write server will be installed.
@@ -177,17 +177,36 @@ type Config struct {
 type ServingInfo struct {
 	// BindAddress is the ip:port to serve on
 	BindAddress string
+}
+
+type SecureServingInfo struct {
+	ServingInfo
+
 	// ServerCert is the TLS cert info for serving secure traffic
-	ServerCert CertInfo
+	ServerCert GeneratableKeyCert
+	// SNICerts are named CertKeys for serving secure traffic with SNI support.
+	SNICerts []NamedCertKey
 	// ClientCA is the certificate bundle for all the signers that you'll recognize for incoming client certificates
 	ClientCA string
 }
 
-type CertInfo struct {
+type CertKey struct {
 	// CertFile is a file containing a PEM-encoded certificate
 	CertFile string
 	// KeyFile is a file containing a PEM-encoded private key for the certificate specified by CertFile
 	KeyFile string
+}
+
+type NamedCertKey struct {
+	CertKey
+
+	// Names is a list of domain patterns: fully qualified domain names, possibly prefixed with
+	// wildcard segments.
+	Names []string
+}
+
+type GeneratableKeyCert struct {
+	CertKey
 	// Generate indicates that the cert/key pair should be generated if its not present.
 	Generate bool
 }
@@ -248,12 +267,17 @@ func (c *Config) ApplyOptions(options *options.ServerRunOptions) *Config {
 	}
 
 	if options.SecurePort > 0 {
-		secureServingInfo := &ServingInfo{
+		secureServingInfo := &SecureServingInfo{
+			ServingInfo: ServingInfo{
 				BindAddress: net.JoinHostPort(options.BindAddress.String(), strconv.Itoa(options.SecurePort)),
-			ServerCert: CertInfo{
+			},
+			ServerCert: GeneratableKeyCert{
+				CertKey: CertKey{
 					CertFile: options.TLSCertFile,
 					KeyFile:  options.TLSPrivateKeyFile,
 				},
+			},
+			SNICerts: []NamedCertKey{},
 			ClientCA: options.ClientCAFile,
 		}
 		if options.TLSCertFile == "" && options.TLSPrivateKeyFile == "" {
@@ -262,6 +286,17 @@ func (c *Config) ApplyOptions(options *options.ServerRunOptions) *Config {
 			secureServingInfo.ServerCert.KeyFile = path.Join(options.CertDirectory, "apiserver.key")
 		}
 
+		secureServingInfo.SNICerts = nil
+		for _, nkc := range options.SNICertKeys {
+			secureServingInfo.SNICerts = append(secureServingInfo.SNICerts, NamedCertKey{
+				CertKey: CertKey{
+					KeyFile:  nkc.KeyFile,
+					CertFile: nkc.CertFile,
+				},
+				Names: nkc.Names,
+			})
+		}
+
 		c.SecureServingInfo = secureServingInfo
 		c.ReadWritePort = options.SecurePort
 	}
@@ -434,9 +469,16 @@ func (c completedConfig) MaybeGenerateServingCerts() error {
 		alternateIPs := []net.IP{c.ServiceReadWriteIP}
 		alternateDNS := []string{"kubernetes.default.svc", "kubernetes.default", "kubernetes", "localhost"}
 
-		if err := certutil.GenerateSelfSignedCert(c.PublicAddress.String(), c.SecureServingInfo.ServerCert.CertFile, c.SecureServingInfo.ServerCert.KeyFile, alternateIPs, alternateDNS); err != nil {
+		if cert, key, err := certutil.GenerateSelfSignedCertKey(c.PublicAddress.String(), alternateIPs, alternateDNS); err != nil {
-			return fmt.Errorf("Unable to generate self signed cert: %v", err)
+			return fmt.Errorf("unable to generate self signed cert: %v", err)
 		} else {
+			if err := certutil.WriteCert(c.SecureServingInfo.ServerCert.CertFile, cert); err != nil {
+				return err
+			}
+
+			if err := certutil.WriteKey(c.SecureServingInfo.ServerCert.KeyFile, key); err != nil {
+				return err
+			}
 			glog.Infof("Generated self-signed cert (%s, %s)", c.SecureServingInfo.ServerCert.CertFile, c.SecureServingInfo.ServerCert.KeyFile)
 		}
 	}

pkg/genericapiserver/genericapiserver.go

@@ -109,7 +109,7 @@ type GenericAPIServer struct {
 	// The registered APIs
 	HandlerContainer *genericmux.APIContainer
 
-	SecureServingInfo   *ServingInfo
+	SecureServingInfo   *SecureServingInfo
 	InsecureServingInfo *ServingInfo
 
 	// numerical ports, set after listening

pkg/genericapiserver/options/server_run_options.go

@@ -118,6 +118,7 @@ type ServerRunOptions struct {
 	TLSCAFile              string
 	TLSCertFile            string
 	TLSPrivateKeyFile      string
+	SNICertKeys            []config.NamedCertKey
 	TokenAuthFile          string
 	EnableAnyToken         bool
 	WatchCacheSizes        []string
@@ -488,13 +489,22 @@ func (s *ServerRunOptions) AddUniversalFlags(fs *pflag.FlagSet) {
 		"Controllers. This must be a valid PEM-encoded CA bundle.")
 
 	fs.StringVar(&s.TLSCertFile, "tls-cert-file", s.TLSCertFile, ""+
-		"File containing x509 Certificate for HTTPS. (CA cert, if any, concatenated "+
+		"File containing the default x509 Certificate for HTTPS. (CA cert, if any, concatenated "+
 		"after server cert). If HTTPS serving is enabled, and --tls-cert-file and "+
 		"--tls-private-key-file are not provided, a self-signed certificate and key "+
 		"are generated for the public address and saved to /var/run/kubernetes.")
 
 	fs.StringVar(&s.TLSPrivateKeyFile, "tls-private-key-file", s.TLSPrivateKeyFile,
-		"File containing x509 private key matching --tls-cert-file.")
+		"File containing the default x509 private key matching --tls-cert-file.")
+
+	fs.Var(config.NewNamedCertKeyArray(&s.SNICertKeys), "tls-sni-cert-key", ""+
+		"A pair of x509 certificate and private key file paths, optionally suffixed with a list of "+
+		"domain patterns which are fully qualified domain names, possibly with prefixed wildcard "+
+		"segments. If no domain patterns are provided, the names of the certificate are "+
+		"extracted. Non-wildcard matches trump over wildcard matches, explicit domain patterns "+
+		"trump over extracted names. For multiple key/certificate pairs, use the "+
+		"--tls-sni-cert-key multiple times. "+
+		"Examples: \"example.key,example.crt\" or \"*.foo.com,foo.com:foo.key,foo.crt\".")
 
 	fs.StringVar(&s.TokenAuthFile, "token-auth-file", s.TokenAuthFile, ""+
 		"If set, the file that will be used to secure the secure port of the API server "+

pkg/genericapiserver/serve.go

@@ -40,11 +40,17 @@ const (
 // be loaded or the initial listen call fails. The actual server loop (stoppable by closing
 // stopCh) runs in a go routine, i.e. serveSecurely does not block.
 func (s *GenericAPIServer) serveSecurely(stopCh <-chan struct{}) error {
+	namedCerts, err := getNamedCertificateMap(s.SecureServingInfo.SNICerts)
+	if err != nil {
+		return fmt.Errorf("unable to load SNI certificates: %v", err)
+	}
+
 	secureServer := &http.Server{
 		Addr:           s.SecureServingInfo.BindAddress,
 		Handler:        s.Handler,
 		MaxHeaderBytes: 1 << 20,
 		TLSConfig: &tls.Config{
+			NameToCertificate: namedCerts,
 			// Can't use SSLv3 because of POODLE and BEAST
 			// Can't use TLSv1.0 because of POODLE and BEAST using CBC cipher
 			// Can't use TLSv1.1 because of RC4 cipher usage
@@ -54,7 +60,6 @@ func (s *GenericAPIServer) serveSecurely(stopCh <-chan struct{}) error {
 		},
 	}
 
-	var err error
 	if len(s.SecureServingInfo.ServerCert.CertFile) != 0 || len(s.SecureServingInfo.ServerCert.KeyFile) != 0 {
 		secureServer.TLSConfig.Certificates = make([]tls.Certificate, 1)
 		secureServer.TLSConfig.Certificates[0], err = tls.LoadX509KeyPair(s.SecureServingInfo.ServerCert.CertFile, s.SecureServingInfo.ServerCert.KeyFile)
@@ -63,6 +68,14 @@ func (s *GenericAPIServer) serveSecurely(stopCh <-chan struct{}) error {
 		}
 	}
 
+	// append all named certs. Otherwise, the go tls stack will think no SNI processing
+	// is necessary because there is only one cert anyway.
+	// Moreover, if ServerCert.CertFile/ServerCert.KeyFile are not set, the first SNI
+	// cert will become the default cert. That's what we expect anyway.
+	for _, c := range namedCerts {
+		secureServer.TLSConfig.Certificates = append(secureServer.TLSConfig.Certificates, *c)
+	}
+
 	if len(s.SecureServingInfo.ClientCA) > 0 {
 		clientCAs, err := certutil.NewPool(s.SecureServingInfo.ClientCA)
 		if err != nil {

pkg/genericapiserver/serve_test.go

@@ -0,0 +1,506 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package genericapiserver
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/base64"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"os"
+	"testing"
+
+	utilcert "k8s.io/kubernetes/pkg/util/cert"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type TestCertSpec struct {
+	host       string
+	names, ips []string // in certificate
+}
+
+type NamedTestCertSpec struct {
+	TestCertSpec
+	explicitNames []string // as --tls-sni-cert-key explicit names
+}
+
+func createTestCerts(spec TestCertSpec) (certFilePath, keyFilePath string, err error) {
+	var ips []net.IP
+	for _, ip := range spec.ips {
+		ips = append(ips, net.ParseIP(ip))
+	}
+
+	certPem, keyPem, err := utilcert.GenerateSelfSignedCertKey(spec.host, ips, spec.names)
+	if err != nil {
+		return "", "", err
+	}
+
+	certFile, err := ioutil.TempFile(os.TempDir(), "cert")
+	if err != nil {
+		return "", "", err
+	}
+
+	keyFile, err := ioutil.TempFile(os.TempDir(), "key")
+	if err != nil {
+		os.Remove(certFile.Name())
+		return "", "", err
+	}
+
+	_, err = certFile.Write(certPem)
+	if err != nil {
+		os.Remove(certFile.Name())
+		os.Remove(keyFile.Name())
+		return "", "", err
+	}
+	certFile.Close()
+
+	_, err = keyFile.Write(keyPem)
+	if err != nil {
+		os.Remove(certFile.Name())
+		os.Remove(keyFile.Name())
+		return "", "", err
+	}
+	keyFile.Close()
+
+	return certFile.Name(), keyFile.Name(), nil
+}
+
+func TestGetNamedCertificateMap(t *testing.T) {
+	tests := []struct {
+		certs         []NamedTestCertSpec
+		explicitNames []string
+		expected      map[string]int // name to certs[*] index
+		errorString   string
+	}{
+		{
+			// empty certs
+			expected: map[string]int{},
+		},
+		{
+			// only one cert
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+				},
+			},
+			expected: map[string]int{
+				"test.com": 0,
+			},
+		},
+		{
+			// ips are ignored
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+						ips:  []string{"1.2.3.4"},
+					},
+				},
+			},
+			expected: map[string]int{
+				"test.com": 0,
+			},
+		},
+		{
+			// two certs with the same name
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+				},
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+				},
+			},
+			expected: map[string]int{
+				"test.com": 0,
+			},
+		},
+		{
+			// two certs with different names
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test2.com",
+					},
+				},
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test1.com",
+					},
+				},
+			},
+			expected: map[string]int{
+				"test1.com": 1,
+				"test2.com": 0,
+			},
+		},
+		{
+			// two certs with the same name, explicit trumps
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+				},
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+					explicitNames: []string{"test.com"},
+				},
+			},
+			expected: map[string]int{
+				"test.com": 1,
+			},
+		},
+		{
+			// certs with partial overlap; ips are ignored
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host:  "a",
+						names: []string{"a.test.com", "test.com"},
+					},
+				},
+				{
+					TestCertSpec: TestCertSpec{
+						host:  "b",
+						names: []string{"b.test.com", "test.com"},
+					},
+				},
+			},
+			expected: map[string]int{
+				"a": 0, "b": 1,
+				"a.test.com": 0, "b.test.com": 1,
+				"test.com": 0,
+			},
+		},
+		{
+			// wildcards
+			certs: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host:  "a",
+						names: []string{"a.test.com", "test.com"},
+					},
+					explicitNames: []string{"*.test.com", "test.com"},
+				},
+				{
+					TestCertSpec: TestCertSpec{
+						host:  "b",
+						names: []string{"b.test.com", "test.com"},
+					},
+					explicitNames: []string{"dev.test.com", "test.com"},
+				}},
+			expected: map[string]int{
+				"test.com":     0,
+				"*.test.com":   0,
+				"dev.test.com": 1,
+			},
+		},
+	}
+
+NextTest:
+	for i, test := range tests {
+		var namedCertKeys []NamedCertKey
+		bySignature := map[string]int{} // index in test.certs by cert signature
+		for j, c := range test.certs {
+			certFile, keyFile, err := createTestCerts(c.TestCertSpec)
+			if err != nil {
+				t.Errorf("%d - failed to create cert %d: %v", i, j, err)
+				continue NextTest
+			}
+			defer os.Remove(certFile)
+			defer os.Remove(keyFile)
+
+			namedCertKeys = append(namedCertKeys, NamedCertKey{
+				CertKey: CertKey{
+					KeyFile:  keyFile,
+					CertFile: certFile,
+				},
+				Names: c.explicitNames,
+			})
+
+			sig, err := certFileSignature(certFile, keyFile)
+			if err != nil {
+				t.Errorf("%d - failed to get signature for %d: %v", i, j, err)
+				continue NextTest
+			}
+			bySignature[sig] = j
+		}
+
+		certMap, err := getNamedCertificateMap(namedCertKeys)
+		if err == nil && len(test.errorString) != 0 {
+			t.Errorf("%d - expected no error, got: %v", i, err)
+		} else if err != nil && err.Error() != test.errorString {
+			t.Errorf("%d - expected error %q, got: %v", i, test.errorString, err)
+		} else {
+			got := map[string]int{}
+			for name, cert := range certMap {
+				x509Certs, err := x509.ParseCertificates(cert.Certificate[0])
+				assert.NoError(t, err, "%d - invalid certificate for %q", i, name)
+				assert.True(t, len(x509Certs) > 0, "%d - expected at least one x509 cert in tls cert for %q", i, name)
+				got[name] = bySignature[x509CertSignature(x509Certs[0])]
+			}
+
+			assert.EqualValues(t, test.expected, got, "%d - wrong certificate map", i)
+		}
+	}
+}
+
+func TestServerRunWithSNI(t *testing.T) {
+	tests := []struct {
+		Cert              TestCertSpec
+		SNICerts          []NamedTestCertSpec
+		ExpectedCertIndex int
+
+		// passed in the client hello info, "localhost" if unset
+		ServerName string
+	}{
+		{
+			// only one cert
+			Cert: TestCertSpec{
+				host: "localhost",
+			},
+			ExpectedCertIndex: -1,
+		},
+		{
+			// cert with multiple alternate names
+			Cert: TestCertSpec{
+				host:  "localhost",
+				names: []string{"test.com"},
+				ips:   []string{"127.0.0.1"},
+			},
+			ExpectedCertIndex: -1,
+			ServerName:        "test.com",
+		},
+		{
+			// one SNI and the default cert with the same name
+			Cert: TestCertSpec{
+				host: "localhost",
+			},
+			SNICerts: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "localhost",
+					},
+				},
+			},
+			ExpectedCertIndex: 0,
+		},
+		{
+			// matching SNI cert
+			Cert: TestCertSpec{
+				host: "localhost",
+			},
+			SNICerts: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+					},
+				},
+			},
+			ExpectedCertIndex: 0,
+			ServerName:        "test.com",
+		},
+		{
+			// matching IP in SNI cert and the server cert. But IPs must not be
+			// passed via SNI. Hence, the ServerName in the HELLO packet is empty
+			// and the server should select the non-SNI cert.
+			Cert: TestCertSpec{
+				host: "localhost",
+				ips:  []string{"10.0.0.1"},
+			},
+			SNICerts: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host: "test.com",
+						ips:  []string{"10.0.0.1"},
+					},
+				},
+			},
+			ExpectedCertIndex: -1,
+			ServerName:        "10.0.0.1",
+		},
+		{
+			// wildcards
+			Cert: TestCertSpec{
+				host: "localhost",
+			},
+			SNICerts: []NamedTestCertSpec{
+				{
+					TestCertSpec: TestCertSpec{
+						host:  "test.com",
+						names: []string{"*.test.com"},
+					},
+				},
+			},
+			ExpectedCertIndex: 0,
+			ServerName:        "www.test.com",
+		},
+	}
+
+NextTest:
+	for i, test := range tests {
+		// create server cert
+		serverCertFile, serverKeyFile, err := createTestCerts(test.Cert)
+		if err != nil {
+			t.Errorf("%d - failed to create server cert: %v", i, err)
+		}
+		defer os.Remove(serverCertFile)
+		defer os.Remove(serverKeyFile)
+
+		// create SNI certs
+		var namedCertKeys []NamedCertKey
+		serverSig, err := certFileSignature(serverCertFile, serverKeyFile)
+		if err != nil {
+			t.Errorf("%d - failed to get server cert signature: %v", i, err)
+			continue NextTest
+		}
+		signatures := map[string]int{
+			serverSig: -1,
+		}
+		for j, c := range test.SNICerts {
+			certFile, keyFile, err := createTestCerts(c.TestCertSpec)
+			if err != nil {
+				t.Errorf("%d - failed to create SNI cert %d: %v", i, j, err)
+				continue NextTest
+			}
+			defer os.Remove(certFile)
+			defer os.Remove(keyFile)
+
+			namedCertKeys = append(namedCertKeys, NamedCertKey{
+				CertKey: CertKey{
+					KeyFile:  keyFile,
+					CertFile: certFile,
+				},
+				Names: c.explicitNames,
+			})
+
+			// store index in namedCertKeys with the signature as the key
+			sig, err := certFileSignature(certFile, keyFile)
+			if err != nil {
+				t.Errorf("%d - failed get SNI cert %d signature: %v", i, j, err)
+				continue NextTest
+			}
+			signatures[sig] = j
+		}
+
+		stopCh := make(chan struct{})
+
+		// launch server
+		etcdserver, config, _ := setUp(t)
+		defer etcdserver.Terminate(t)
+
+		config.EnableIndex = true
+		config.SecureServingInfo = &SecureServingInfo{
+			ServingInfo: ServingInfo{
+				BindAddress: "localhost:0",
+			},
+			ServerCert: GeneratableKeyCert{
+				CertKey: CertKey{
+					CertFile: serverCertFile,
+					KeyFile:  serverKeyFile,
+				},
+			},
+			SNICerts: namedCertKeys,
+		}
+		config.InsecureServingInfo = nil
+
+		s, err := config.Complete().New()
+		if err != nil {
+			t.Errorf("%d - failed creating the server: %v", i, err)
+			continue NextTest
+		}
+
+		if err := s.serveSecurely(stopCh); err != nil {
+			t.Errorf("%d - failed running the server: %v", i, err)
+			continue NextTest
+		}
+
+		// load certificates into a pool
+		roots := x509.NewCertPool()
+		certFiles := []string{serverCertFile}
+		for _, c := range namedCertKeys {
+			certFiles = append(certFiles, c.CertFile)
+		}
+		for _, certFile := range certFiles {
+			bs, err := ioutil.ReadFile(certFile)
+			if err != nil {
+				t.Errorf("%d - error reading %q: %v", i, certFile, err)
+				continue NextTest
+			}
+			if ok := roots.AppendCertsFromPEM(bs); !ok {
+				t.Errorf("%d - error adding cert %q to the pool", i, certFile)
+				continue NextTest
+			}
+		}
+
+		// try to dial
+		addr := fmt.Sprintf("localhost:%d", s.effectiveSecurePort)
+		t.Logf("Dialing %s as %q", addr, test.ServerName)
+		conn, err := tls.Dial("tcp", addr, &tls.Config{
+			RootCAs:    roots,
+			ServerName: test.ServerName, // used for SNI in the client HELLO packet
+		})
+		if err != nil {
+			t.Errorf("%d - failed to connect: %v", i, err)
+			continue NextTest
+		}
+
+		// check returned server certificate
+		sig := x509CertSignature(conn.ConnectionState().PeerCertificates[0])
+		gotCertIndex, found := signatures[sig]
+		if !found {
+			t.Errorf("%d - unknown signature returned from server: %s", i, sig)
+		}
+		if gotCertIndex != test.ExpectedCertIndex {
+			t.Errorf("%d - expected cert index %d, got cert index %d", i, test.ExpectedCertIndex, gotCertIndex)
+		}
+
+		conn.Close()
+	}
+}
+
+func x509CertSignature(cert *x509.Certificate) string {
+	return base64.StdEncoding.EncodeToString(cert.Signature)
+}
+
+func certFileSignature(certFile, keyFile string) (string, error) {
+	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+	if err != nil {
+		return "", err
+	}
+
+	x509Certs, err := x509.ParseCertificates(cert.Certificate[0])
+	if err != nil {
+		return "", err
+	}
+	if len(x509Certs) == 0 {
+		return "", fmt.Errorf("expected at least one cert after reparsing cert %q", certFile)
+	}
+	return x509CertSignature(x509Certs[0]), nil
+}

pkg/util/cert/cert.go

@@ -126,22 +126,19 @@ func MakeEllipticPrivateKeyPEM() ([]byte, error) {
 	return pem.EncodeToMemory(privateKeyPemBlock), nil
 }
 
-// GenerateSelfSignedCert creates a self-signed certificate and key for the given host.
+// GenerateSelfSignedCertKey creates a self-signed certificate and key for the given host.
 // Host may be an IP or a DNS name
 // You may also specify additional subject alt names (either ip or dns names) for the certificate
-// The certificate will be created with file mode 0644. The key will be created with file mode 0600.
+func GenerateSelfSignedCertKey(host string, alternateIPs []net.IP, alternateDNS []string) ([]byte, []byte, error) {
-// If the certificate or key files already exist, they will be overwritten.
-// Any parent directories of the certPath or keyPath will be created as needed with file mode 0755.
-func GenerateSelfSignedCert(host, certPath, keyPath string, alternateIPs []net.IP, alternateDNS []string) error {
 	priv, err := rsa.GenerateKey(cryptorand.Reader, 2048)
 	if err != nil {
-		return err
+		return nil, nil, err
 	}
 
 	template := x509.Certificate{
 		SerialNumber: big.NewInt(1),
 		Subject: pkix.Name{
-			CommonName: fmt.Sprintf("%s@%d", host, time.Now().Unix()),
+			CommonName: host,
 		},
 		NotBefore: time.Now(),
 		NotAfter:  time.Now().Add(time.Hour * 24 * 365),
@@ -163,30 +160,22 @@ func GenerateSelfSignedCert(host, certPath, keyPath string, alternateIPs []net.I
 
 	derBytes, err := x509.CreateCertificate(cryptorand.Reader, &template, &template, &priv.PublicKey, priv)
 	if err != nil {
-		return err
+		return nil, nil, err
 	}
 
 	// Generate cert
 	certBuffer := bytes.Buffer{}
 	if err := pem.Encode(&certBuffer, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
-		return err
+		return nil, nil, err
 	}
 
 	// Generate key
 	keyBuffer := bytes.Buffer{}
 	if err := pem.Encode(&keyBuffer, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)}); err != nil {
-		return err
+		return nil, nil, err
 	}
 
-	if err := WriteCert(certPath, certBuffer.Bytes()); err != nil {
+	return certBuffer.Bytes(), keyBuffer.Bytes(), nil
-		return err
-	}
-
-	if err := WriteKey(keyPath, keyBuffer.Bytes()); err != nil {
-		return err
-	}
-
-	return nil
 }
 
 // FormatBytesCert receives byte array certificate and formats in human-readable format

pkg/util/config/namedcertkey_flag.go

@@ -0,0 +1,113 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package config
+
+import (
+	"errors"
+	"flag"
+	"strings"
+)
+
+// NamedCertKey is a flag value parsing "certfile,keyfile" and "certfile,keyfile:name,name,name".
+type NamedCertKey struct {
+	Names             []string
+	CertFile, KeyFile string
+}
+
+var _ flag.Value = &NamedCertKey{}
+
+func (nkc *NamedCertKey) String() string {
+	s := nkc.CertFile + "," + nkc.KeyFile
+	if len(nkc.Names) > 0 {
+		s = s + ":" + strings.Join(nkc.Names, ",")
+	}
+	return s
+}
+
+func (nkc *NamedCertKey) Set(value string) error {
+	cs := strings.SplitN(value, ":", 2)
+	var keycert string
+	if len(cs) == 2 {
+		var names string
+		keycert, names = strings.TrimSpace(cs[0]), strings.TrimSpace(cs[1])
+		if names == "" {
+			return errors.New("empty names list is not allowed")
+		}
+		nkc.Names = nil
+		for _, name := range strings.Split(names, ",") {
+			nkc.Names = append(nkc.Names, strings.TrimSpace(name))
+		}
+	} else {
+		nkc.Names = nil
+		keycert = strings.TrimSpace(cs[0])
+	}
+	cs = strings.Split(keycert, ",")
+	if len(cs) != 2 {
+		return errors.New("expected comma separated certificate and key file paths")
+	}
+	nkc.CertFile = strings.TrimSpace(cs[0])
+	nkc.KeyFile = strings.TrimSpace(cs[1])
+	return nil
+}
+
+func (*NamedCertKey) Type() string {
+	return "namedCertKey"
+}
+
+// NamedCertKeyArray is a flag value parsing NamedCertKeys, each passed with its own
+// flag instance (in contrast to comma separated slices).
+type NamedCertKeyArray struct {
+	value   *[]NamedCertKey
+	changed bool
+}
+
+var _ flag.Value = &NamedCertKey{}
+
+// NewNamedKeyCertArray creates a new NamedCertKeyArray with the internal value
+// pointing to p.
+func NewNamedCertKeyArray(p *[]NamedCertKey) *NamedCertKeyArray {
+	return &NamedCertKeyArray{
+		value: p,
+	}
+}
+
+func (a *NamedCertKeyArray) Set(val string) error {
+	nkc := NamedCertKey{}
+	err := nkc.Set(val)
+	if err != nil {
+		return err
+	}
+	if !a.changed {
+		*a.value = []NamedCertKey{nkc}
+		a.changed = true
+	} else {
+		*a.value = append(*a.value, nkc)
+	}
+	return nil
+}
+
+func (a *NamedCertKeyArray) Type() string {
+	return "namedCertKey"
+}
+
+func (a *NamedCertKeyArray) String() string {
+	nkcs := make([]string, 0, len(*a.value))
+	for i := range *a.value {
+		nkcs = append(nkcs, (*a.value)[i].String())
+	}
+	return "[" + strings.Join(nkcs, ";") + "]"
+}

pkg/util/config/namedcertkey_flag_test.go

@@ -0,0 +1,138 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package config
+
+import (
+	"fmt"
+	"github.com/spf13/pflag"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestNamedCertKeyArrayFlag(t *testing.T) {
+	tests := []struct {
+		args       []string
+		def        []NamedCertKey
+		expected   []NamedCertKey
+		parseError string
+	}{
+		{
+			args:     []string{},
+			expected: nil,
+		},
+		{
+			args: []string{"foo.crt,foo.key"},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+			}},
+		},
+		{
+			args: []string{"  foo.crt , foo.key    "},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+			}},
+		},
+		{
+			args: []string{"foo.crt,foo.key:abc"},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+				Names:    []string{"abc"},
+			}},
+		},
+		{
+			args: []string{"foo.crt,foo.key: abc  "},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+				Names:    []string{"abc"},
+			}},
+		},
+		{
+			args:       []string{"foo.crt,foo.key:"},
+			parseError: "empty names list is not allowed",
+		},
+		{
+			args:       []string{""},
+			parseError: "expected comma separated certificate and key file paths",
+		},
+		{
+			args:       []string{"   "},
+			parseError: "expected comma separated certificate and key file paths",
+		},
+		{
+			args:       []string{"a,b,c"},
+			parseError: "expected comma separated certificate and key file paths",
+		},
+		{
+			args: []string{"foo.crt,foo.key:abc,def,ghi"},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+				Names:    []string{"abc", "def", "ghi"},
+			}},
+		},
+		{
+			args: []string{"foo.crt,foo.key:*.*.*"},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+				Names:    []string{"*.*.*"},
+			}},
+		},
+		{
+			args: []string{"foo.crt,foo.key", "bar.crt,bar.key"},
+			expected: []NamedCertKey{{
+				KeyFile:  "foo.key",
+				CertFile: "foo.crt",
+			}, {
+				KeyFile:  "bar.key",
+				CertFile: "bar.crt",
+			}},
+		},
+	}
+	for i, test := range tests {
+		fs := pflag.NewFlagSet("testNamedCertKeyArray", pflag.ContinueOnError)
+		var nkcs []NamedCertKey
+		for _, d := range test.def {
+			nkcs = append(nkcs, d)
+		}
+		fs.Var(NewNamedCertKeyArray(&nkcs), "tls-sni-cert-key", "usage")
+
+		args := []string{}
+		for _, a := range test.args {
+			args = append(args, fmt.Sprintf("--tls-sni-cert-key=%s", a))
+		}
+
+		err := fs.Parse(args)
+		if test.parseError != "" {
+			if err == nil {
+				t.Errorf("%d: expected error %q, got nil", i, test.parseError)
+			} else if !strings.Contains(err.Error(), test.parseError) {
+				t.Errorf("%d: expected error %q, got %q", i, test.parseError, err)
+			}
+		} else if err != nil {
+			t.Errorf("%d: expected nil error, got %v", i, err)
+		}
+		if !reflect.DeepEqual(nkcs, test.expected) {
+			t.Errorf("%d: expected %+v, got %+v", i, test.expected, nkcs)
+		}
+	}
+}