-
Notifications
You must be signed in to change notification settings - Fork 4.9k
/
healthcheck.go
433 lines (366 loc) · 11.9 KB
/
healthcheck.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
package healthcheck
import (
"context"
"errors"
"fmt"
"net"
"net/http"
"net/url"
"strconv"
"strings"
"sync"
"time"
gokitmetrics "github.com/go-kit/kit/metrics"
"github.com/traefik/traefik/v2/pkg/config/dynamic"
"github.com/traefik/traefik/v2/pkg/config/runtime"
"github.com/traefik/traefik/v2/pkg/log"
"github.com/traefik/traefik/v2/pkg/metrics"
"github.com/traefik/traefik/v2/pkg/safe"
"github.com/vulcand/oxy/v2/roundrobin"
)
const (
serverUp = "UP"
serverDown = "DOWN"
)
var (
singleton *HealthCheck
once sync.Once
)
// Balancer is the set of operations required to manage the list of servers in a load-balancer.
type Balancer interface {
Servers() []*url.URL
RemoveServer(u *url.URL) error
UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error
}
// BalancerHandler includes functionality for load-balancing management.
type BalancerHandler interface {
ServeHTTP(w http.ResponseWriter, req *http.Request)
Balancer
}
// BalancerStatusHandler is an http Handler that does load-balancing,
// and updates its parents of its status.
type BalancerStatusHandler interface {
BalancerHandler
StatusUpdater
}
type metricsHealthcheck struct {
serverUpGauge gokitmetrics.Gauge
}
// Options are the public health check options.
type Options struct {
Headers map[string]string
Hostname string
Scheme string
Path string
Method string
Port int
FollowRedirects bool
Transport http.RoundTripper
Interval time.Duration
Timeout time.Duration
LB Balancer
}
func (opt Options) String() string {
return fmt.Sprintf("[Hostname: %s Headers: %v Path: %s Method: %s Port: %d Interval: %s Timeout: %s FollowRedirects: %v]", opt.Hostname, opt.Headers, opt.Path, opt.Method, opt.Port, opt.Interval, opt.Timeout, opt.FollowRedirects)
}
type backendURL struct {
url *url.URL
weight int
}
// BackendConfig HealthCheck configuration for a backend.
type BackendConfig struct {
Options
name string
disabledURLs []backendURL
}
func (b *BackendConfig) newRequest(serverURL *url.URL) (*http.Request, error) {
u, err := serverURL.Parse(b.Path)
if err != nil {
return nil, err
}
if len(b.Scheme) > 0 {
u.Scheme = b.Scheme
}
if b.Port != 0 {
u.Host = net.JoinHostPort(u.Hostname(), strconv.Itoa(b.Port))
}
return http.NewRequest(http.MethodGet, u.String(), http.NoBody)
}
// setRequestOptions sets all request options present on the BackendConfig.
func (b *BackendConfig) setRequestOptions(req *http.Request) *http.Request {
if b.Options.Hostname != "" {
req.Host = b.Options.Hostname
}
for k, v := range b.Options.Headers {
req.Header.Set(k, v)
}
if b.Options.Method != "" {
req.Method = strings.ToUpper(b.Options.Method)
}
return req
}
// HealthCheck struct.
type HealthCheck struct {
Backends map[string]*BackendConfig
metrics metricsHealthcheck
cancel context.CancelFunc
}
// SetBackendsConfiguration set backends configuration.
func (hc *HealthCheck) SetBackendsConfiguration(parentCtx context.Context, backends map[string]*BackendConfig) {
hc.Backends = backends
if hc.cancel != nil {
hc.cancel()
}
ctx, cancel := context.WithCancel(parentCtx)
hc.cancel = cancel
for _, backend := range backends {
currentBackend := backend
safe.Go(func() {
hc.execute(ctx, currentBackend)
})
}
}
func (hc *HealthCheck) execute(ctx context.Context, backend *BackendConfig) {
logger := log.FromContext(ctx)
logger.Debugf("Initial health check for backend: %q", backend.name)
hc.checkServersLB(ctx, backend)
ticker := time.NewTicker(backend.Interval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
logger.Debugf("Stopping current health check goroutines of backend: %s", backend.name)
return
case <-ticker.C:
logger.Debugf("Routine health check refresh for backend: %s", backend.name)
hc.checkServersLB(ctx, backend)
}
}
}
func (hc *HealthCheck) checkServersLB(ctx context.Context, backend *BackendConfig) {
logger := log.FromContext(ctx)
enabledURLs := backend.LB.Servers()
var newDisabledURLs []backendURL
for _, disabledURL := range backend.disabledURLs {
serverUpMetricValue := float64(0)
if err := checkHealth(disabledURL.url, backend); err == nil {
logger.Warnf("Health check up: returning to server list. Backend: %q URL: %q Weight: %d",
backend.name, disabledURL.url.String(), disabledURL.weight)
if err = backend.LB.UpsertServer(disabledURL.url, roundrobin.Weight(disabledURL.weight)); err != nil {
logger.Error(err)
}
serverUpMetricValue = 1
} else {
logger.Warnf("Health check still failing. Backend: %q URL: %q Reason: %s", backend.name, disabledURL.url.String(), err)
newDisabledURLs = append(newDisabledURLs, disabledURL)
}
labelValues := []string{"service", backend.name, "url", disabledURL.url.String()}
hc.metrics.serverUpGauge.With(labelValues...).Set(serverUpMetricValue)
}
backend.disabledURLs = newDisabledURLs
for _, enabledURL := range enabledURLs {
serverUpMetricValue := float64(1)
if err := checkHealth(enabledURL, backend); err != nil {
weight := 1
rr, ok := backend.LB.(*roundrobin.RoundRobin)
if ok {
var gotWeight bool
weight, gotWeight = rr.ServerWeight(enabledURL)
if !gotWeight {
weight = 1
}
}
logger.Warnf("Health check failed, removing from server list. Backend: %q URL: %q Weight: %d Reason: %s",
backend.name, enabledURL.String(), weight, err)
if err := backend.LB.RemoveServer(enabledURL); err != nil {
logger.Error(err)
}
backend.disabledURLs = append(backend.disabledURLs, backendURL{enabledURL, weight})
serverUpMetricValue = 0
}
labelValues := []string{"service", backend.name, "url", enabledURL.String()}
hc.metrics.serverUpGauge.With(labelValues...).Set(serverUpMetricValue)
}
}
// GetHealthCheck returns the health check which is guaranteed to be a singleton.
func GetHealthCheck(registry metrics.Registry) *HealthCheck {
once.Do(func() {
singleton = newHealthCheck(registry)
})
return singleton
}
func newHealthCheck(registry metrics.Registry) *HealthCheck {
return &HealthCheck{
Backends: make(map[string]*BackendConfig),
metrics: metricsHealthcheck{
serverUpGauge: registry.ServiceServerUpGauge(),
},
}
}
// NewBackendConfig Instantiate a new BackendConfig.
func NewBackendConfig(options Options, backendName string) *BackendConfig {
return &BackendConfig{
Options: options,
name: backendName,
}
}
// checkHealth returns a nil error in case it was successful and otherwise
// a non-nil error with a meaningful description why the health check failed.
func checkHealth(serverURL *url.URL, backend *BackendConfig) error {
req, err := backend.newRequest(serverURL)
if err != nil {
return fmt.Errorf("failed to create HTTP request: %w", err)
}
req = backend.setRequestOptions(req)
client := http.Client{
Timeout: backend.Options.Timeout,
Transport: backend.Options.Transport,
}
if !backend.FollowRedirects {
client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
}
}
resp, err := client.Do(req)
if err != nil {
return fmt.Errorf("HTTP request failed: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusBadRequest {
return fmt.Errorf("received error status code: %v", resp.StatusCode)
}
return nil
}
// StatusUpdater should be implemented by a service that, when its status
// changes (e.g. all if its children are down), needs to propagate upwards (to
// their parent(s)) that change.
type StatusUpdater interface {
RegisterStatusUpdater(fn func(up bool)) error
}
// NewLBStatusUpdater returns a new LbStatusUpdater.
func NewLBStatusUpdater(bh BalancerHandler, info *runtime.ServiceInfo, hc *dynamic.ServerHealthCheck) *LbStatusUpdater {
return &LbStatusUpdater{
BalancerHandler: bh,
serviceInfo: info,
wantsHealthCheck: hc != nil,
}
}
// LbStatusUpdater wraps a BalancerHandler and a ServiceInfo,
// so it can keep track of the status of a server in the ServiceInfo.
type LbStatusUpdater struct {
BalancerHandler
serviceInfo *runtime.ServiceInfo // can be nil
updaters []func(up bool)
wantsHealthCheck bool
}
// RegisterStatusUpdater adds fn to the list of hooks that are run when the
// status of the Balancer changes.
// Not thread safe.
func (lb *LbStatusUpdater) RegisterStatusUpdater(fn func(up bool)) error {
if !lb.wantsHealthCheck {
return errors.New("healthCheck not enabled in config for this loadbalancer service")
}
lb.updaters = append(lb.updaters, fn)
return nil
}
// RemoveServer removes the given server from the BalancerHandler,
// and updates the status of the server to "DOWN".
func (lb *LbStatusUpdater) RemoveServer(u *url.URL) error {
// TODO(mpl): when we have the freedom to change the signature of RemoveServer
// (kinda stuck because of oxy for now), let's pass around a context to improve
// logging.
ctx := context.TODO()
upBefore := len(lb.BalancerHandler.Servers()) > 0
err := lb.BalancerHandler.RemoveServer(u)
if err != nil {
return err
}
if lb.serviceInfo != nil {
lb.serviceInfo.UpdateServerStatus(u.String(), serverDown)
}
log.FromContext(ctx).Debugf("child %s now %s", u.String(), serverDown)
if !upBefore {
// we were already down, and we still are, no need to propagate.
log.FromContext(ctx).Debugf("Still %s, no need to propagate", serverDown)
return nil
}
if len(lb.BalancerHandler.Servers()) > 0 {
// we were up, and we still are, no need to propagate
log.FromContext(ctx).Debugf("Still %s, no need to propagate", serverUp)
return nil
}
log.FromContext(ctx).Debugf("Propagating new %s status", serverDown)
for _, fn := range lb.updaters {
fn(false)
}
return nil
}
// UpsertServer adds the given server to the BalancerHandler,
// and updates the status of the server to "UP".
func (lb *LbStatusUpdater) UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error {
ctx := context.TODO()
upBefore := len(lb.BalancerHandler.Servers()) > 0
err := lb.BalancerHandler.UpsertServer(u, options...)
if err != nil {
return err
}
if lb.serviceInfo != nil {
lb.serviceInfo.UpdateServerStatus(u.String(), serverUp)
}
log.FromContext(ctx).Debugf("child %s now %s", u.String(), serverUp)
if upBefore {
// we were up, and we still are, no need to propagate
log.FromContext(ctx).Debugf("Still %s, no need to propagate", serverUp)
return nil
}
log.FromContext(ctx).Debugf("Propagating new %s status", serverUp)
for _, fn := range lb.updaters {
fn(true)
}
return nil
}
// Balancers is a list of Balancers(s) that implements the Balancer interface.
type Balancers []Balancer
// Servers returns the deduplicated server URLs from all the Balancer.
// Note that the deduplication is only possible because all the underlying
// balancers are of the same kind (the oxy implementation).
// The comparison property is the same as the one found at:
// https://github.com/vulcand/oxy/blob/fb2728c857b7973a27f8de2f2190729c0f22cf49/roundrobin/rr.go#L347.
func (b Balancers) Servers() []*url.URL {
seen := make(map[string]struct{})
var servers []*url.URL
for _, lb := range b {
for _, server := range lb.Servers() {
key := serverKey(server)
if _, ok := seen[key]; ok {
continue
}
servers = append(servers, server)
seen[key] = struct{}{}
}
}
return servers
}
// RemoveServer removes the given server from all the Balancer,
// and updates the status of the server to "DOWN".
func (b Balancers) RemoveServer(u *url.URL) error {
for _, lb := range b {
if err := lb.RemoveServer(u); err != nil {
return err
}
}
return nil
}
// UpsertServer adds the given server to all the Balancer,
// and updates the status of the server to "UP".
func (b Balancers) UpsertServer(u *url.URL, options ...roundrobin.ServerOption) error {
for _, lb := range b {
if err := lb.UpsertServer(u, options...); err != nil {
return err
}
}
return nil
}
func serverKey(u *url.URL) string {
return u.Path + u.Host + u.Scheme
}