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serving.go 12.23 KB
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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
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.
package options
import (
utilnet "k8s.io/apimachinery/pkg/util/net"
certutil "k8s.io/client-go/util/cert"
cliflag "k8s.io/component-base/cli/flag"
type SecureServingOptions struct {
BindAddress net.IP
// BindPort is ignored when Listener is set, will serve https even with 0.
BindPort int
// BindNetwork is the type of network to bind to - defaults to "tcp", accepts "tcp",
// "tcp4", and "tcp6".
BindNetwork string
// Required set to true means that BindPort cannot be zero.
Required bool
// ExternalAddress is the address advertised, even if BindAddress is a loopback. By default this
// is set to BindAddress if the later no loopback, or to the first host interface address.
ExternalAddress net.IP
// Listener is the secure server network listener.
// either Listener or BindAddress/BindPort/BindNetwork is set,
// if Listener is set, use it and omit BindAddress/BindPort/BindNetwork.
Listener net.Listener
// ServerCert is the TLS cert info for serving secure traffic
ServerCert GeneratableKeyCert
// SNICertKeys are named CertKeys for serving secure traffic with SNI support.
SNICertKeys []cliflag.NamedCertKey
// CipherSuites is the list of allowed cipher suites for the server.
// Values are from tls package constants (https://golang.org/pkg/crypto/tls/#pkg-constants).
CipherSuites []string
// MinTLSVersion is the minimum TLS version supported.
// Values are from tls package constants (https://golang.org/pkg/crypto/tls/#pkg-constants).
MinTLSVersion string
// HTTP2MaxStreamsPerConnection is the limit that the api server imposes on each client.
// A value of zero means to use the default provided by golang's HTTP/2 support.
HTTP2MaxStreamsPerConnection int
type CertKey struct {
// CertFile is a file containing a PEM-encoded certificate, and possibly the complete certificate chain
CertFile string
// KeyFile is a file containing a PEM-encoded private key for the certificate specified by CertFile
KeyFile string
type GeneratableKeyCert struct {
// CertKey allows setting an explicit cert/key file to use.
CertKey CertKey
// CertDirectory specifies a directory to write generated certificates to if CertFile/KeyFile aren't explicitly set.
// PairName is used to determine the filenames within CertDirectory.
// If CertDirectory and PairName are not set, an in-memory certificate will be generated.
CertDirectory string
// PairName is the name which will be used with CertDirectory to make a cert and key filenames.
// It becomes CertDirectory/PairName.crt and CertDirectory/PairName.key
PairName string
// GeneratedCert holds an in-memory generated certificate if CertFile/KeyFile aren't explicitly set, and CertDirectory/PairName are not set.
GeneratedCert *tls.Certificate
// FixtureDirectory is a directory that contains test fixture used to avoid regeneration of certs during tests.
// The format is:
// <host>_<ip>-<ip>_<alternateDNS>-<alternateDNS>.crt
// <host>_<ip>-<ip>_<alternateDNS>-<alternateDNS>.key
FixtureDirectory string
func NewSecureServingOptions() *SecureServingOptions {
return &SecureServingOptions{
BindAddress: net.ParseIP(""),
BindPort: 443,
ServerCert: GeneratableKeyCert{
PairName: "apiserver",
CertDirectory: "apiserver.local.config/certificates",
func (s *SecureServingOptions) DefaultExternalAddress() (net.IP, error) {
if !s.ExternalAddress.IsUnspecified() {
return s.ExternalAddress, nil
return utilnet.ChooseBindAddress(s.BindAddress)
func (s *SecureServingOptions) Validate() []error {
if s == nil {
return nil
errors := []error{}
if s.Required && s.BindPort < 1 || s.BindPort > 65535 {
errors = append(errors, fmt.Errorf("--secure-port %v must be between 1 and 65535, inclusive. It cannot be turned off with 0", s.BindPort))
} else if s.BindPort < 0 || s.BindPort > 65535 {
errors = append(errors, fmt.Errorf("--secure-port %v must be between 0 and 65535, inclusive. 0 for turning off secure port", s.BindPort))
if (len(s.ServerCert.CertKey.CertFile) != 0 || len(s.ServerCert.CertKey.KeyFile) != 0) && s.ServerCert.GeneratedCert != nil {
errors = append(errors, fmt.Errorf("cert/key file and in-memory certificate cannot both be set"))
return errors
func (s *SecureServingOptions) AddFlags(fs *pflag.FlagSet) {
if s == nil {
fs.IPVar(&s.BindAddress, "bind-address", s.BindAddress, ""+
"The IP address on which to listen for the --secure-port port. The "+
"associated interface(s) must be reachable by the rest of the cluster, and by CLI/web "+
"clients. If blank, all interfaces will be used ( for all IPv4 interfaces and :: for all IPv6 interfaces).")
desc := "The port on which to serve HTTPS with authentication and authorization."
if s.Required {
desc += "It cannot be switched off with 0."
} else {
desc += "If 0, don't serve HTTPS at all."
fs.IntVar(&s.BindPort, "secure-port", s.BindPort, desc)
fs.StringVar(&s.ServerCert.CertDirectory, "cert-dir", s.ServerCert.CertDirectory, ""+
"The directory where the TLS certs are located. "+
"If --tls-cert-file and --tls-private-key-file are provided, this flag will be ignored.")
fs.StringVar(&s.ServerCert.CertKey.CertFile, "tls-cert-file", s.ServerCert.CertKey.CertFile, ""+
"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 the directory specified by --cert-dir.")
fs.StringVar(&s.ServerCert.CertKey.KeyFile, "tls-private-key-file", s.ServerCert.CertKey.KeyFile,
"File containing the default x509 private key matching --tls-cert-file.")
tlsCipherPossibleValues := cliflag.TLSCipherPossibleValues()
fs.StringSliceVar(&s.CipherSuites, "tls-cipher-suites", s.CipherSuites,
"Comma-separated list of cipher suites for the server. "+
"If omitted, the default Go cipher suites will be use. "+
"Possible values: "+strings.Join(tlsCipherPossibleValues, ","))
tlsPossibleVersions := cliflag.TLSPossibleVersions()
fs.StringVar(&s.MinTLSVersion, "tls-min-version", s.MinTLSVersion,
"Minimum TLS version supported. "+
"Possible values: "+strings.Join(tlsPossibleVersions, ", "))
fs.Var(cliflag.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.crt,example.key\" or \"foo.crt,foo.key:*.foo.com,foo.com\".")
fs.IntVar(&s.HTTP2MaxStreamsPerConnection, "http2-max-streams-per-connection", s.HTTP2MaxStreamsPerConnection, ""+
"The limit that the server gives to clients for "+
"the maximum number of streams in an HTTP/2 connection. "+
"Zero means to use golang's default.")
// ApplyTo fills up serving information in the server configuration.
func (s *SecureServingOptions) ApplyTo(config **server.SecureServingInfo) error {
if s == nil {
return nil
if s.BindPort <= 0 && s.Listener == nil {
return nil
if s.Listener == nil {
var err error
addr := net.JoinHostPort(s.BindAddress.String(), strconv.Itoa(s.BindPort))
s.Listener, s.BindPort, err = CreateListener(s.BindNetwork, addr)
if err != nil {
return fmt.Errorf("failed to create listener: %v", err)
} else {
if _, ok := s.Listener.Addr().(*net.TCPAddr); !ok {
return fmt.Errorf("failed to parse ip and port from listener")
s.BindPort = s.Listener.Addr().(*net.TCPAddr).Port
s.BindAddress = s.Listener.Addr().(*net.TCPAddr).IP
*config = &server.SecureServingInfo{
Listener: s.Listener,
HTTP2MaxStreamsPerConnection: s.HTTP2MaxStreamsPerConnection,
c := *config
serverCertFile, serverKeyFile := s.ServerCert.CertKey.CertFile, s.ServerCert.CertKey.KeyFile
// load main cert
if len(serverCertFile) != 0 || len(serverKeyFile) != 0 {
tlsCert, err := tls.LoadX509KeyPair(serverCertFile, serverKeyFile)
if err != nil {
return fmt.Errorf("unable to load server certificate: %v", err)
c.Cert = &tlsCert
} else if s.ServerCert.GeneratedCert != nil {
c.Cert = s.ServerCert.GeneratedCert
if len(s.CipherSuites) != 0 {
cipherSuites, err := cliflag.TLSCipherSuites(s.CipherSuites)
if err != nil {
return err
c.CipherSuites = cipherSuites
var err error
c.MinTLSVersion, err = cliflag.TLSVersion(s.MinTLSVersion)
if err != nil {
return err
// load SNI certs
namedTLSCerts := make([]server.NamedTLSCert, 0, len(s.SNICertKeys))
for _, nck := range s.SNICertKeys {
tlsCert, err := tls.LoadX509KeyPair(nck.CertFile, nck.KeyFile)
namedTLSCerts = append(namedTLSCerts, server.NamedTLSCert{
TLSCert: tlsCert,
Names: nck.Names,
if err != nil {
return fmt.Errorf("failed to load SNI cert and key: %v", err)
c.SNICerts, err = server.GetNamedCertificateMap(namedTLSCerts)
if err != nil {
return err
return nil
func (s *SecureServingOptions) MaybeDefaultWithSelfSignedCerts(publicAddress string, alternateDNS []string, alternateIPs []net.IP) error {
if s == nil || (s.BindPort == 0 && s.Listener == nil) {
return nil
keyCert := &s.ServerCert.CertKey
if len(keyCert.CertFile) != 0 || len(keyCert.KeyFile) != 0 {
return nil
canReadCertAndKey := false
if len(s.ServerCert.CertDirectory) > 0 {
if len(s.ServerCert.PairName) == 0 {
return fmt.Errorf("PairName is required if CertDirectory is set")
keyCert.CertFile = path.Join(s.ServerCert.CertDirectory, s.ServerCert.PairName+".crt")
keyCert.KeyFile = path.Join(s.ServerCert.CertDirectory, s.ServerCert.PairName+".key")
if canRead, err := certutil.CanReadCertAndKey(keyCert.CertFile, keyCert.KeyFile); err != nil {
return err
} else {
canReadCertAndKey = canRead
if !canReadCertAndKey {
// add either the bind address or localhost to the valid alternates
bindIP := s.BindAddress.String()
if bindIP == "" {
alternateDNS = append(alternateDNS, "localhost")
} else {
alternateIPs = append(alternateIPs, s.BindAddress)
if cert, key, err := certutil.GenerateSelfSignedCertKeyWithFixtures(publicAddress, alternateIPs, alternateDNS, s.ServerCert.FixtureDirectory); err != nil {
return fmt.Errorf("unable to generate self signed cert: %v", err)
} else if len(keyCert.CertFile) > 0 && len(keyCert.KeyFile) > 0 {
if err := certutil.WriteCert(keyCert.CertFile, cert); err != nil {
return err
if err := keyutil.WriteKey(keyCert.KeyFile, key); err != nil {
return err
klog.Infof("Generated self-signed cert (%s, %s)", keyCert.CertFile, keyCert.KeyFile)
} else {
tlsCert, err := tls.X509KeyPair(cert, key)
if err != nil {
return fmt.Errorf("unable to generate self signed cert: %v", err)
s.ServerCert.GeneratedCert = &tlsCert
klog.Infof("Generated self-signed cert in-memory")
return nil
func CreateListener(network, addr string) (net.Listener, int, error) {
if len(network) == 0 {
network = "tcp"
ln, err := net.Listen(network, addr)
if err != nil {
return nil, 0, fmt.Errorf("failed to listen on %v: %v", addr, err)
// get port
tcpAddr, ok := ln.Addr().(*net.TCPAddr)
if !ok {
return nil, 0, fmt.Errorf("invalid listen address: %q", ln.Addr().String())
return ln, tcpAddr.Port, nil

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