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/*
Copyright 2018 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 transport
import (
"fmt"
"io/ioutil"
"net/http"
"strings"
"sync"
"time"
"golang.org/x/oauth2"
"k8s.io/klog"
)
// TokenSourceWrapTransport returns a WrapTransport that injects bearer tokens
// authentication from an oauth2.TokenSource.
func TokenSourceWrapTransport(ts oauth2.TokenSource) func(http.RoundTripper) http.RoundTripper {
return func(rt http.RoundTripper) http.RoundTripper {
return &tokenSourceTransport{
base: rt,
ort: &oauth2.Transport{
Source: ts,
Base: rt,
},
}
}
}
// NewCachedFileTokenSource returns a oauth2.TokenSource reads a token from a
// file at a specified path and periodically reloads it.
func NewCachedFileTokenSource(path string) oauth2.TokenSource {
return &cachingTokenSource{
now: time.Now,
leeway: 10 * time.Second,
base: &fileTokenSource{
path: path,
// This period was picked because it is half of the duration between when the kubelet
// refreshes a projected service account token and when the original token expires.
// Default token lifetime is 10 minutes, and the kubelet starts refreshing at 80% of lifetime.
// This should induce re-reading at a frequency that works with the token volume source.
period: time.Minute,
},
}
}
// NewCachedTokenSource returns a oauth2.TokenSource reads a token from a
// designed TokenSource. The ts would provide the source of token.
func NewCachedTokenSource(ts oauth2.TokenSource) oauth2.TokenSource {
return &cachingTokenSource{
now: time.Now,
base: ts,
}
}
type tokenSourceTransport struct {
base http.RoundTripper
ort http.RoundTripper
}
func (tst *tokenSourceTransport) RoundTrip(req *http.Request) (*http.Response, error) {
// This is to allow --token to override other bearer token providers.
if req.Header.Get("Authorization") != "" {
return tst.base.RoundTrip(req)
}
return tst.ort.RoundTrip(req)
}
type fileTokenSource struct {
path string
period time.Duration
}
var _ = oauth2.TokenSource(&fileTokenSource{})
func (ts *fileTokenSource) Token() (*oauth2.Token, error) {
tokb, err := ioutil.ReadFile(ts.path)
if err != nil {
return nil, fmt.Errorf("failed to read token file %q: %v", ts.path, err)
}
tok := strings.TrimSpace(string(tokb))
if len(tok) == 0 {
return nil, fmt.Errorf("read empty token from file %q", ts.path)
}
return &oauth2.Token{
AccessToken: tok,
Expiry: time.Now().Add(ts.period),
}, nil
}
type cachingTokenSource struct {
base oauth2.TokenSource
leeway time.Duration
sync.RWMutex
tok *oauth2.Token
// for testing
now func() time.Time
}
var _ = oauth2.TokenSource(&cachingTokenSource{})
func (ts *cachingTokenSource) Token() (*oauth2.Token, error) {
now := ts.now()
// fast path
ts.RLock()
tok := ts.tok
ts.RUnlock()
if tok != nil && tok.Expiry.Add(-1*ts.leeway).After(now) {
return tok, nil
}
// slow path
ts.Lock()
defer ts.Unlock()
if tok := ts.tok; tok != nil && tok.Expiry.Add(-1*ts.leeway).After(now) {
return tok, nil
}
tok, err := ts.base.Token()
if err != nil {
if ts.tok == nil {
return nil, err
}
klog.Errorf("Unable to rotate token: %v", err)
return ts.tok, nil
}
ts.tok = tok
return tok, nil
}
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