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dex/storage/kubernetes/transport.go

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package kubernetes
import (
"net/http"
"os"
"sync"
"time"
"github.com/dexidp/dex/storage/kubernetes/k8sapi"
)
// transport is a simple http.Transport wrapper
type transport struct {
updateReq func(r *http.Request)
base http.RoundTripper
}
func (t transport) RoundTrip(r *http.Request) (*http.Response, error) {
// shallow copy of the struct
r2 := new(http.Request)
*r2 = *r
// deep copy of the Header
r2.Header = make(http.Header, len(r.Header))
for k, s := range r.Header {
r2.Header[k] = append([]string(nil), s...)
}
t.updateReq(r2)
return t.base.RoundTrip(r2)
}
func wrapRoundTripper(base http.RoundTripper, user k8sapi.AuthInfo, inCluster bool) http.RoundTripper {
if inCluster {
inClusterTransportHelper := newInClusterTransportHelper(user)
return transport{
updateReq: func(r *http.Request) {
inClusterTransportHelper.UpdateToken()
r.Header.Set("Authorization", "Bearer "+inClusterTransportHelper.GetToken())
},
base: base,
}
}
if user.Token != "" {
return transport{
updateReq: func(r *http.Request) {
r.Header.Set("Authorization", "Bearer "+user.Token)
},
base: base,
}
}
if user.Username != "" && user.Password != "" {
return transport{
updateReq: func(r *http.Request) {
r.SetBasicAuth(user.Username, user.Password)
},
base: base,
}
}
return base
}
// renewTokenPeriod is the interval after which dex will read the token from a well-known file.
// By Kubernetes documentation, this interval should be at least one minute long.
// Kubernetes client-go v0.15+ uses 10 seconds long interval.
// Dex uses the reasonable value between these two.
const renewTokenPeriod = 30 * time.Second
// inClusterTransportHelper is capable of safely updating the user token.
// BoundServiceAccountTokenVolume feature is enabled in Kubernetes >=1.21 by default.
// With this feature, the service account token in the pod becomes periodically updated.
// Therefore, Dex needs to re-read the token from the disk after some time to be sure that it uses the valid token.
type inClusterTransportHelper struct {
mu sync.RWMutex
info k8sapi.AuthInfo
expiry time.Time
now func() time.Time
tokenLocation string
}
func newInClusterTransportHelper(info k8sapi.AuthInfo) *inClusterTransportHelper {
user := &inClusterTransportHelper{
info: info,
now: time.Now,
tokenLocation: "/var/run/secrets/kubernetes.io/serviceaccount/token",
}
user.UpdateToken()
return user
}
func (c *inClusterTransportHelper) UpdateToken() {
c.mu.RLock()
exp := c.expiry
c.mu.RUnlock()
if !c.now().After(exp) {
// Do not need to update token yet
return
}
token, err := os.ReadFile(c.tokenLocation)
if err != nil {
return
}
c.mu.Lock()
defer c.mu.Unlock()
c.info.Token = string(token)
c.expiry = c.now().Add(renewTokenPeriod)
}
func (c *inClusterTransportHelper) GetToken() string {
c.mu.RLock()
defer c.mu.RUnlock()
return c.info.Token
}