-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
watch.go
299 lines (263 loc) · 7.96 KB
/
watch.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
package nomad
import (
"context"
"encoding/json"
"errors"
"flag"
"fmt"
"net/url"
"sync"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape/discoveryutils"
"github.com/VictoriaMetrics/metrics"
)
// SDCheckInterval is check interval for Nomad service discovery.
var SDCheckInterval = flag.Duration("promscrape.nomadSDCheckInterval", 30*time.Second, "Interval for checking for changes in Nomad. "+
"This works only if nomad_sd_configs is configured in '-promscrape.config' file. "+
"See https://docs.victoriametrics.com/sd_configs.html#nomad_sd_configs for details")
// nomadWatcher is a watcher for nomad api, updates services map in background with long-polling.
type nomadWatcher struct {
client *discoveryutils.Client
serviceNamesQueryArgs string
// servicesLock protects services
servicesLock sync.Mutex
services map[string]*serviceWatcher
stoppedCh chan struct{}
}
type serviceWatcher struct {
serviceName string
services []Service
stoppedCh chan struct{}
requestCtx context.Context
requestCancel context.CancelFunc
}
// newNomadWatcher creates new watcher and starts background service discovery for Nomad.
func newNomadWatcher(client *discoveryutils.Client, sdc *SDConfig, namespace, region string) *nomadWatcher {
qa := url.Values{}
if sdc.AllowStale == nil || *sdc.AllowStale {
qa.Set("stale", "")
}
if namespace != "" {
qa.Set("namespace", namespace)
}
if region != "" {
qa.Set("region", region)
}
queryArgs := qa.Encode()
if queryArgs != "" {
queryArgs = "?" + queryArgs
}
cw := &nomadWatcher{
client: client,
serviceNamesQueryArgs: queryArgs,
services: make(map[string]*serviceWatcher),
stoppedCh: make(chan struct{}),
}
initCh := make(chan struct{})
go func() {
cw.watchForServicesUpdates(initCh)
close(cw.stoppedCh)
}()
// wait for initialization to complete
<-initCh
return cw
}
func (cw *nomadWatcher) mustStop() {
cw.client.Stop()
<-cw.stoppedCh
}
func (cw *nomadWatcher) updateServices(serviceNames []string) {
var initWG sync.WaitGroup
// Start watchers for new services.
cw.servicesLock.Lock()
for _, serviceName := range serviceNames {
if _, ok := cw.services[serviceName]; ok {
// The watcher for serviceName already exists.
continue
}
ctx, cancel := context.WithCancel(cw.client.Context())
sw := &serviceWatcher{
serviceName: serviceName,
stoppedCh: make(chan struct{}),
requestCtx: ctx,
requestCancel: cancel,
}
cw.services[serviceName] = sw
serviceWatchersCreated.Inc()
initWG.Add(1)
go func() {
serviceWatchersCount.Inc()
sw.watchForServiceAddressUpdates(cw, &initWG)
serviceWatchersCount.Dec()
close(sw.stoppedCh)
}()
}
// Stop watchers for removed services.
newServiceNamesMap := make(map[string]struct{}, len(serviceNames))
for _, serviceName := range serviceNames {
newServiceNamesMap[serviceName] = struct{}{}
}
var swsStopped []*serviceWatcher
for serviceName, sw := range cw.services {
if _, ok := newServiceNamesMap[serviceName]; ok {
continue
}
sw.requestCancel()
delete(cw.services, serviceName)
swsStopped = append(swsStopped, sw)
}
cw.servicesLock.Unlock()
// Wait until deleted service watchers are stopped.
for _, sw := range swsStopped {
<-sw.stoppedCh
serviceWatchersStopped.Inc()
}
// Wait until added service watchers are initialized.
initWG.Wait()
}
// watchForServicesUpdates watches for new services and updates it in cw.
//
// watchForServicesUpdates closes the initCh once the initialization is complete and first discovery iteration is done.
func (cw *nomadWatcher) watchForServicesUpdates(initCh chan struct{}) {
index := int64(0)
apiServer := cw.client.APIServer()
f := func() {
serviceNames, newIndex, err := cw.getBlockingServiceNames(index)
if err != nil {
if !errors.Is(err, context.Canceled) {
logger.Errorf("cannot obtain Nomad serviceNames from %q: %s", apiServer, err)
}
return
}
if index == newIndex {
// Nothing changed.
return
}
cw.updateServices(serviceNames)
index = newIndex
}
logger.Infof("started Nomad service watcher for %q", apiServer)
f()
// send signal that initialization is complete
close(initCh)
checkInterval := getCheckInterval()
ticker := time.NewTicker(checkInterval / 2)
defer ticker.Stop()
stopCh := cw.client.Context().Done()
for {
select {
case <-ticker.C:
f()
case <-stopCh:
logger.Infof("stopping Nomad service watchers for %q", apiServer)
startTime := time.Now()
var swsStopped []*serviceWatcher
cw.servicesLock.Lock()
for _, sw := range cw.services {
sw.requestCancel()
swsStopped = append(swsStopped, sw)
}
cw.servicesLock.Unlock()
for _, sw := range swsStopped {
<-sw.stoppedCh
serviceWatchersStopped.Inc()
}
logger.Infof("stopped Nomad service watcher for %q in %.3f seconds", apiServer, time.Since(startTime).Seconds())
return
}
}
}
var (
serviceWatchersCreated = metrics.NewCounter("vm_promscrape_discovery_nomad_service_watchers_created_total")
serviceWatchersStopped = metrics.NewCounter("vm_promscrape_discovery_nomad_service_watchers_stopped_total")
serviceWatchersCount = metrics.NewCounter("vm_promscrape_discovery_nomad_service_watchers")
)
// getBlockingServiceNames obtains service names via blocking request to Nomad.
//
// It returns an empty serviceNames list if response contains the same index.
func (cw *nomadWatcher) getBlockingServiceNames(index int64) ([]string, int64, error) {
path := "/v1/services" + cw.serviceNamesQueryArgs
data, newIndex, err := getBlockingAPIResponse(cw.client.Context(), cw.client, path, index)
if err != nil {
return nil, index, err
}
if index == newIndex {
// Nothing changed - return an empty serviceNames list.
return nil, index, nil
}
var svcs []ServiceList
if err := json.Unmarshal(data, &svcs); err != nil {
return nil, index, fmt.Errorf("cannot parse response from %q: %w; data=%q", path, err, data)
}
serviceNames := make([]string, 0, len(svcs))
for _, svc := range svcs {
for _, s := range svc.Services {
serviceNames = append(serviceNames, s.ServiceName)
}
}
return serviceNames, newIndex, nil
}
// getServiceSnapshot returns a snapshot of discovered Services.
func (cw *nomadWatcher) getServiceSnapshot() map[string][]Service {
cw.servicesLock.Lock()
sns := make(map[string][]Service, len(cw.services))
for svc, sw := range cw.services {
sns[svc] = sw.services
}
cw.servicesLock.Unlock()
return sns
}
// watchForServiceNodesUpdates watches for Nomad serviceNode changes for the given serviceName.
//
// watchForServiceNodesUpdates calls initWG.Done() once the initialization is complete and the first discovery iteration is done.
func (sw *serviceWatcher) watchForServiceAddressUpdates(nw *nomadWatcher, initWG *sync.WaitGroup) {
apiServer := nw.client.APIServer()
index := int64(0)
// TODO: Maybe use a different query arg.
path := "/v1/service/" + sw.serviceName + nw.serviceNamesQueryArgs
f := func() {
data, newIndex, err := getBlockingAPIResponse(sw.requestCtx, nw.client, path, index)
if err != nil {
if !errors.Is(err, context.Canceled) {
logger.Errorf("cannot obtain Nomad services for serviceName=%q from %q: %s", sw.serviceName, apiServer, err)
}
return
}
if index == newIndex {
// Nothing changed.
return
}
sns, err := parseServices(data)
if err != nil {
logger.Errorf("cannot parse Nomad services response for serviceName=%q from %q: %s", sw.serviceName, apiServer, err)
return
}
nw.servicesLock.Lock()
sw.services = sns
nw.servicesLock.Unlock()
index = newIndex
}
f()
// Notify caller that initialization is complete
initWG.Done()
checkInterval := getCheckInterval()
ticker := time.NewTicker(checkInterval / 2)
defer ticker.Stop()
stopCh := sw.requestCtx.Done()
for {
select {
case <-ticker.C:
f()
case <-stopCh:
return
}
}
}
func getCheckInterval() time.Duration {
d := *SDCheckInterval
if d <= time.Second {
return time.Second
}
return d
}