-
Notifications
You must be signed in to change notification settings - Fork 39.2k
/
transport.go
159 lines (138 loc) · 5.81 KB
/
transport.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
/*
Copyright 2017 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 certificate
import (
"crypto/tls"
"fmt"
"net"
"net/http"
"time"
"k8s.io/klog/v2"
utilnet "k8s.io/apimachinery/pkg/util/net"
"k8s.io/apimachinery/pkg/util/wait"
restclient "k8s.io/client-go/rest"
"k8s.io/client-go/util/certificate"
"k8s.io/client-go/util/connrotation"
)
// UpdateTransport instruments a restconfig with a transport that dynamically uses
// certificates provided by the manager for TLS client auth.
//
// The config must not already provide an explicit transport.
//
// The returned function allows forcefully closing all active connections.
//
// The returned transport periodically checks the manager to determine if the
// certificate has changed. If it has, the transport shuts down all existing client
// connections, forcing the client to re-handshake with the server and use the
// new certificate.
//
// The exitAfter duration, if set, will terminate the current process if a certificate
// is not available from the store (because it has been deleted on disk or is corrupt)
// or if the certificate has expired and the server is responsive. This allows the
// process parent or the bootstrap credentials an opportunity to retrieve a new initial
// certificate.
//
// stopCh should be used to indicate when the transport is unused and doesn't need
// to continue checking the manager.
func UpdateTransport(stopCh <-chan struct{}, clientConfig *restclient.Config, clientCertificateManager certificate.Manager, exitAfter time.Duration) (func(), error) {
return updateTransport(stopCh, 10*time.Second, clientConfig, clientCertificateManager, exitAfter)
}
// updateTransport is an internal method that exposes how often this method checks that the
// client cert has changed.
func updateTransport(stopCh <-chan struct{}, period time.Duration, clientConfig *restclient.Config, clientCertificateManager certificate.Manager, exitAfter time.Duration) (func(), error) {
if clientConfig.Transport != nil || clientConfig.Dial != nil {
return nil, fmt.Errorf("there is already a transport or dialer configured")
}
d := connrotation.NewDialer((&net.Dialer{Timeout: 30 * time.Second, KeepAlive: 30 * time.Second}).DialContext)
if clientCertificateManager != nil {
if err := addCertRotation(stopCh, period, clientConfig, clientCertificateManager, exitAfter, d); err != nil {
return nil, err
}
} else {
clientConfig.Dial = d.DialContext
}
return d.CloseAll, nil
}
func addCertRotation(stopCh <-chan struct{}, period time.Duration, clientConfig *restclient.Config, clientCertificateManager certificate.Manager, exitAfter time.Duration, d *connrotation.Dialer) error {
tlsConfig, err := restclient.TLSConfigFor(clientConfig)
if err != nil {
return fmt.Errorf("unable to configure TLS for the rest client: %v", err)
}
if tlsConfig == nil {
tlsConfig = &tls.Config{}
}
tlsConfig.Certificates = nil
tlsConfig.GetClientCertificate = func(requestInfo *tls.CertificateRequestInfo) (*tls.Certificate, error) {
cert := clientCertificateManager.Current()
if cert == nil {
return &tls.Certificate{Certificate: nil}, nil
}
return cert, nil
}
lastCertAvailable := time.Now()
lastCert := clientCertificateManager.Current()
go wait.Until(func() {
curr := clientCertificateManager.Current()
if exitAfter > 0 {
now := time.Now()
if curr == nil {
// the certificate has been deleted from disk or is otherwise corrupt
if now.After(lastCertAvailable.Add(exitAfter)) {
if clientCertificateManager.ServerHealthy() {
klog.Fatalf("It has been %s since a valid client cert was found and the server is responsive, exiting.", exitAfter)
} else {
klog.Errorf("It has been %s since a valid client cert was found, but the server is not responsive. A restart may be necessary to retrieve new initial credentials.", exitAfter)
}
}
} else {
// the certificate is expired
if now.After(curr.Leaf.NotAfter) {
if clientCertificateManager.ServerHealthy() {
klog.Fatalf("The currently active client certificate has expired and the server is responsive, exiting.")
} else {
klog.Errorf("The currently active client certificate has expired, but the server is not responsive. A restart may be necessary to retrieve new initial credentials.")
}
}
lastCertAvailable = now
}
}
if curr == nil || lastCert == curr {
// Cert hasn't been rotated.
return
}
lastCert = curr
klog.Infof("certificate rotation detected, shutting down client connections to start using new credentials")
// The cert has been rotated. Close all existing connections to force the client
// to reperform its TLS handshake with new cert.
//
// See: https://github.com/kubernetes-incubator/bootkube/pull/663#issuecomment-318506493
d.CloseAll()
}, period, stopCh)
clientConfig.Transport = utilnet.SetTransportDefaults(&http.Transport{
Proxy: http.ProxyFromEnvironment,
TLSHandshakeTimeout: 10 * time.Second,
TLSClientConfig: tlsConfig,
MaxIdleConnsPerHost: 25,
DialContext: d.DialContext,
})
// Zero out all existing TLS options since our new transport enforces them.
clientConfig.CertData = nil
clientConfig.KeyData = nil
clientConfig.CertFile = ""
clientConfig.KeyFile = ""
clientConfig.CAData = nil
clientConfig.CAFile = ""
clientConfig.Insecure = false
clientConfig.NextProtos = nil
return nil
}