forked from etcd-io/etcd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
client.go
703 lines (607 loc) · 17.6 KB
/
client.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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
// Copyright 2015 The etcd 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 client
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"math/rand"
"net"
"net/http"
"net/url"
"sort"
"strconv"
"sync"
"time"
"github.com/coreos/etcd/version"
"golang.org/x/net/context"
)
var (
ErrNoEndpoints = errors.New("client: no endpoints available")
ErrTooManyRedirects = errors.New("client: too many redirects")
ErrClusterUnavailable = errors.New("client: etcd cluster is unavailable or misconfigured")
ErrNoLeaderEndpoint = errors.New("client: no leader endpoint available")
errTooManyRedirectChecks = errors.New("client: too many redirect checks")
// oneShotCtxValue is set on a context using WithValue(&oneShotValue) so
// that Do() will not retry a request
oneShotCtxValue interface{}
)
var DefaultRequestTimeout = 5 * time.Second
var DefaultTransport CancelableTransport = &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
}
type EndpointSelectionMode int
const (
// EndpointSelectionRandom is the default value of the 'SelectionMode'.
// As the name implies, the client object will pick a node from the members
// of the cluster in a random fashion. If the cluster has three members, A, B,
// and C, the client picks any node from its three members as its request
// destination.
EndpointSelectionRandom EndpointSelectionMode = iota
// If 'SelectionMode' is set to 'EndpointSelectionPrioritizeLeader',
// requests are sent directly to the cluster leader. This reduces
// forwarding roundtrips compared to making requests to etcd followers
// who then forward them to the cluster leader. In the event of a leader
// failure, however, clients configured this way cannot prioritize among
// the remaining etcd followers. Therefore, when a client sets 'SelectionMode'
// to 'EndpointSelectionPrioritizeLeader', it must use 'client.AutoSync()' to
// maintain its knowledge of current cluster state.
//
// This mode should be used with Client.AutoSync().
EndpointSelectionPrioritizeLeader
)
type Config struct {
// Endpoints defines a set of URLs (schemes, hosts and ports only)
// that can be used to communicate with a logical etcd cluster. For
// example, a three-node cluster could be provided like so:
//
// Endpoints: []string{
// "http://node1.example.com:2379",
// "http://node2.example.com:2379",
// "http://node3.example.com:2379",
// }
//
// If multiple endpoints are provided, the Client will attempt to
// use them all in the event that one or more of them are unusable.
//
// If Client.Sync is ever called, the Client may cache an alternate
// set of endpoints to continue operation.
Endpoints []string
// Transport is used by the Client to drive HTTP requests. If not
// provided, DefaultTransport will be used.
Transport CancelableTransport
// CheckRedirect specifies the policy for handling HTTP redirects.
// If CheckRedirect is not nil, the Client calls it before
// following an HTTP redirect. The sole argument is the number of
// requests that have already been made. If CheckRedirect returns
// an error, Client.Do will not make any further requests and return
// the error back it to the caller.
//
// If CheckRedirect is nil, the Client uses its default policy,
// which is to stop after 10 consecutive requests.
CheckRedirect CheckRedirectFunc
// Username specifies the user credential to add as an authorization header
Username string
// Password is the password for the specified user to add as an authorization header
// to the request.
Password string
// HeaderTimeoutPerRequest specifies the time limit to wait for response
// header in a single request made by the Client. The timeout includes
// connection time, any redirects, and header wait time.
//
// For non-watch GET request, server returns the response body immediately.
// For PUT/POST/DELETE request, server will attempt to commit request
// before responding, which is expected to take `100ms + 2 * RTT`.
// For watch request, server returns the header immediately to notify Client
// watch start. But if server is behind some kind of proxy, the response
// header may be cached at proxy, and Client cannot rely on this behavior.
//
// Especially, wait request will ignore this timeout.
//
// One API call may send multiple requests to different etcd servers until it
// succeeds. Use context of the API to specify the overall timeout.
//
// A HeaderTimeoutPerRequest of zero means no timeout.
HeaderTimeoutPerRequest time.Duration
// SelectionMode is an EndpointSelectionMode enum that specifies the
// policy for choosing the etcd cluster node to which requests are sent.
SelectionMode EndpointSelectionMode
}
func (cfg *Config) transport() CancelableTransport {
if cfg.Transport == nil {
return DefaultTransport
}
return cfg.Transport
}
func (cfg *Config) checkRedirect() CheckRedirectFunc {
if cfg.CheckRedirect == nil {
return DefaultCheckRedirect
}
return cfg.CheckRedirect
}
// CancelableTransport mimics net/http.Transport, but requires that
// the object also support request cancellation.
type CancelableTransport interface {
http.RoundTripper
CancelRequest(req *http.Request)
}
type CheckRedirectFunc func(via int) error
// DefaultCheckRedirect follows up to 10 redirects, but no more.
var DefaultCheckRedirect CheckRedirectFunc = func(via int) error {
if via > 10 {
return ErrTooManyRedirects
}
return nil
}
type Client interface {
// Sync updates the internal cache of the etcd cluster's membership.
Sync(context.Context) error
// AutoSync periodically calls Sync() every given interval.
// The recommended sync interval is 10 seconds to 1 minute, which does
// not bring too much overhead to server and makes client catch up the
// cluster change in time.
//
// The example to use it:
//
// for {
// err := client.AutoSync(ctx, 10*time.Second)
// if err == context.DeadlineExceeded || err == context.Canceled {
// break
// }
// log.Print(err)
// }
AutoSync(context.Context, time.Duration) error
// Endpoints returns a copy of the current set of API endpoints used
// by Client to resolve HTTP requests. If Sync has ever been called,
// this may differ from the initial Endpoints provided in the Config.
Endpoints() []string
// SetEndpoints sets the set of API endpoints used by Client to resolve
// HTTP requests. If the given endpoints are not valid, an error will be
// returned
SetEndpoints(eps []string) error
// GetVersion retrieves the current etcd server and cluster version
GetVersion(ctx context.Context) (*version.Versions, error)
httpClient
}
func New(cfg Config) (Client, error) {
c := &httpClusterClient{
clientFactory: newHTTPClientFactory(cfg.transport(), cfg.checkRedirect(), cfg.HeaderTimeoutPerRequest),
rand: rand.New(rand.NewSource(int64(time.Now().Nanosecond()))),
selectionMode: cfg.SelectionMode,
}
if cfg.Username != "" {
c.credentials = &credentials{
username: cfg.Username,
password: cfg.Password,
}
}
if err := c.SetEndpoints(cfg.Endpoints); err != nil {
return nil, err
}
return c, nil
}
type httpClient interface {
Do(context.Context, httpAction) (*http.Response, []byte, error)
}
func newHTTPClientFactory(tr CancelableTransport, cr CheckRedirectFunc, headerTimeout time.Duration) httpClientFactory {
return func(ep url.URL) httpClient {
return &redirectFollowingHTTPClient{
checkRedirect: cr,
client: &simpleHTTPClient{
transport: tr,
endpoint: ep,
headerTimeout: headerTimeout,
},
}
}
}
type credentials struct {
username string
password string
}
type httpClientFactory func(url.URL) httpClient
type httpAction interface {
HTTPRequest(url.URL) *http.Request
}
type httpClusterClient struct {
clientFactory httpClientFactory
endpoints []url.URL
pinned int
credentials *credentials
sync.RWMutex
rand *rand.Rand
selectionMode EndpointSelectionMode
}
func (c *httpClusterClient) getLeaderEndpoint(ctx context.Context, eps []url.URL) (string, error) {
ceps := make([]url.URL, len(eps))
copy(ceps, eps)
// To perform a lookup on the new endpoint list without using the current
// client, we'll copy it
clientCopy := &httpClusterClient{
clientFactory: c.clientFactory,
credentials: c.credentials,
rand: c.rand,
pinned: 0,
endpoints: ceps,
}
mAPI := NewMembersAPI(clientCopy)
leader, err := mAPI.Leader(ctx)
if err != nil {
return "", err
}
if len(leader.ClientURLs) == 0 {
return "", ErrNoLeaderEndpoint
}
return leader.ClientURLs[0], nil // TODO: how to handle multiple client URLs?
}
func (c *httpClusterClient) parseEndpoints(eps []string) ([]url.URL, error) {
if len(eps) == 0 {
return []url.URL{}, ErrNoEndpoints
}
neps := make([]url.URL, len(eps))
for i, ep := range eps {
u, err := url.Parse(ep)
if err != nil {
return []url.URL{}, err
}
neps[i] = *u
}
return neps, nil
}
func (c *httpClusterClient) SetEndpoints(eps []string) error {
neps, err := c.parseEndpoints(eps)
if err != nil {
return err
}
c.Lock()
defer c.Unlock()
c.endpoints = shuffleEndpoints(c.rand, neps)
// We're not doing anything for PrioritizeLeader here. This is
// due to not having a context meaning we can't call getLeaderEndpoint
// However, if you're using PrioritizeLeader, you've already been told
// to regularly call sync, where we do have a ctx, and can figure the
// leader. PrioritizeLeader is also quite a loose guarantee, so deal
// with it
c.pinned = 0
return nil
}
func (c *httpClusterClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
action := act
c.RLock()
leps := len(c.endpoints)
eps := make([]url.URL, leps)
n := copy(eps, c.endpoints)
pinned := c.pinned
if c.credentials != nil {
action = &authedAction{
act: act,
credentials: *c.credentials,
}
}
c.RUnlock()
if leps == 0 {
return nil, nil, ErrNoEndpoints
}
if leps != n {
return nil, nil, errors.New("unable to pick endpoint: copy failed")
}
var resp *http.Response
var body []byte
var err error
cerr := &ClusterError{}
isOneShot := ctx.Value(&oneShotCtxValue) != nil
for i := pinned; i < leps+pinned; i++ {
k := i % leps
hc := c.clientFactory(eps[k])
resp, body, err = hc.Do(ctx, action)
if err != nil {
cerr.Errors = append(cerr.Errors, err)
if err == ctx.Err() {
return nil, nil, ctx.Err()
}
if err == context.Canceled || err == context.DeadlineExceeded {
return nil, nil, err
}
if isOneShot {
return nil, nil, err
}
continue
}
if resp.StatusCode/100 == 5 {
switch resp.StatusCode {
case http.StatusInternalServerError, http.StatusServiceUnavailable:
// TODO: make sure this is a no leader response
cerr.Errors = append(cerr.Errors, fmt.Errorf("client: etcd member %s has no leader", eps[k].String()))
default:
cerr.Errors = append(cerr.Errors, fmt.Errorf("client: etcd member %s returns server error [%s]", eps[k].String(), http.StatusText(resp.StatusCode)))
}
if isOneShot {
return nil, nil, cerr.Errors[0]
}
continue
}
if k != pinned {
c.Lock()
c.pinned = k
c.Unlock()
}
return resp, body, nil
}
return nil, nil, cerr
}
func (c *httpClusterClient) Endpoints() []string {
c.RLock()
defer c.RUnlock()
eps := make([]string, len(c.endpoints))
for i, ep := range c.endpoints {
eps[i] = ep.String()
}
return eps
}
func (c *httpClusterClient) Sync(ctx context.Context) error {
mAPI := NewMembersAPI(c)
ms, err := mAPI.List(ctx)
if err != nil {
return err
}
var eps []string
for _, m := range ms {
eps = append(eps, m.ClientURLs...)
}
neps, err := c.parseEndpoints(eps)
if err != nil {
return err
}
npin := 0
switch c.selectionMode {
case EndpointSelectionRandom:
c.RLock()
eq := endpointsEqual(c.endpoints, neps)
c.RUnlock()
if eq {
return nil
}
// When items in the endpoint list changes, we choose a new pin
neps = shuffleEndpoints(c.rand, neps)
case EndpointSelectionPrioritizeLeader:
nle, err := c.getLeaderEndpoint(ctx, neps)
if err != nil {
return ErrNoLeaderEndpoint
}
for i, n := range neps {
if n.String() == nle {
npin = i
break
}
}
default:
return fmt.Errorf("invalid endpoint selection mode: %d", c.selectionMode)
}
c.Lock()
defer c.Unlock()
c.endpoints = neps
c.pinned = npin
return nil
}
func (c *httpClusterClient) AutoSync(ctx context.Context, interval time.Duration) error {
ticker := time.NewTicker(interval)
defer ticker.Stop()
for {
err := c.Sync(ctx)
if err != nil {
return err
}
select {
case <-ctx.Done():
return ctx.Err()
case <-ticker.C:
}
}
}
func (c *httpClusterClient) GetVersion(ctx context.Context) (*version.Versions, error) {
act := &getAction{Prefix: "/version"}
resp, body, err := c.Do(ctx, act)
if err != nil {
return nil, err
}
switch resp.StatusCode {
case http.StatusOK:
if len(body) == 0 {
return nil, ErrEmptyBody
}
var vresp version.Versions
if err := json.Unmarshal(body, &vresp); err != nil {
return nil, ErrInvalidJSON
}
return &vresp, nil
default:
var etcdErr Error
if err := json.Unmarshal(body, &etcdErr); err != nil {
return nil, ErrInvalidJSON
}
return nil, etcdErr
}
}
type roundTripResponse struct {
resp *http.Response
err error
}
type simpleHTTPClient struct {
transport CancelableTransport
endpoint url.URL
headerTimeout time.Duration
}
func (c *simpleHTTPClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
req := act.HTTPRequest(c.endpoint)
if err := printcURL(req); err != nil {
return nil, nil, err
}
isWait := false
if req != nil && req.URL != nil {
ws := req.URL.Query().Get("wait")
if len(ws) != 0 {
var err error
isWait, err = strconv.ParseBool(ws)
if err != nil {
return nil, nil, fmt.Errorf("wrong wait value %s (%v for %+v)", ws, err, req)
}
}
}
var hctx context.Context
var hcancel context.CancelFunc
if !isWait && c.headerTimeout > 0 {
hctx, hcancel = context.WithTimeout(ctx, c.headerTimeout)
} else {
hctx, hcancel = context.WithCancel(ctx)
}
defer hcancel()
reqcancel := requestCanceler(c.transport, req)
rtchan := make(chan roundTripResponse, 1)
go func() {
resp, err := c.transport.RoundTrip(req)
rtchan <- roundTripResponse{resp: resp, err: err}
close(rtchan)
}()
var resp *http.Response
var err error
select {
case rtresp := <-rtchan:
resp, err = rtresp.resp, rtresp.err
case <-hctx.Done():
// cancel and wait for request to actually exit before continuing
reqcancel()
rtresp := <-rtchan
resp = rtresp.resp
switch {
case ctx.Err() != nil:
err = ctx.Err()
case hctx.Err() != nil:
err = fmt.Errorf("client: endpoint %s exceeded header timeout", c.endpoint.String())
default:
panic("failed to get error from context")
}
}
// always check for resp nil-ness to deal with possible
// race conditions between channels above
defer func() {
if resp != nil {
resp.Body.Close()
}
}()
if err != nil {
return nil, nil, err
}
var body []byte
done := make(chan struct{})
go func() {
body, err = ioutil.ReadAll(resp.Body)
done <- struct{}{}
}()
select {
case <-ctx.Done():
resp.Body.Close()
<-done
return nil, nil, ctx.Err()
case <-done:
}
return resp, body, err
}
type authedAction struct {
act httpAction
credentials credentials
}
func (a *authedAction) HTTPRequest(url url.URL) *http.Request {
r := a.act.HTTPRequest(url)
r.SetBasicAuth(a.credentials.username, a.credentials.password)
return r
}
type redirectFollowingHTTPClient struct {
client httpClient
checkRedirect CheckRedirectFunc
}
func (r *redirectFollowingHTTPClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
next := act
for i := 0; i < 100; i++ {
if i > 0 {
if err := r.checkRedirect(i); err != nil {
return nil, nil, err
}
}
resp, body, err := r.client.Do(ctx, next)
if err != nil {
return nil, nil, err
}
if resp.StatusCode/100 == 3 {
hdr := resp.Header.Get("Location")
if hdr == "" {
return nil, nil, fmt.Errorf("Location header not set")
}
loc, err := url.Parse(hdr)
if err != nil {
return nil, nil, fmt.Errorf("Location header not valid URL: %s", hdr)
}
next = &redirectedHTTPAction{
action: act,
location: *loc,
}
continue
}
return resp, body, nil
}
return nil, nil, errTooManyRedirectChecks
}
type redirectedHTTPAction struct {
action httpAction
location url.URL
}
func (r *redirectedHTTPAction) HTTPRequest(ep url.URL) *http.Request {
orig := r.action.HTTPRequest(ep)
orig.URL = &r.location
return orig
}
func shuffleEndpoints(r *rand.Rand, eps []url.URL) []url.URL {
p := r.Perm(len(eps))
neps := make([]url.URL, len(eps))
for i, k := range p {
neps[i] = eps[k]
}
return neps
}
func endpointsEqual(left, right []url.URL) bool {
if len(left) != len(right) {
return false
}
sLeft := make([]string, len(left))
sRight := make([]string, len(right))
for i, l := range left {
sLeft[i] = l.String()
}
for i, r := range right {
sRight[i] = r.String()
}
sort.Strings(sLeft)
sort.Strings(sRight)
for i := range sLeft {
if sLeft[i] != sRight[i] {
return false
}
}
return true
}