/
informed_watcher.go
239 lines (205 loc) · 8.18 KB
/
informed_watcher.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
/*
Copyright 2018 The Knative 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 informer
import (
"errors"
"fmt"
"github.com/Yangfisher1/knative-common-pkg/configmap"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/equality"
k8serrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/selection"
"k8s.io/client-go/informers"
corev1informers "k8s.io/client-go/informers/core/v1"
"k8s.io/client-go/informers/internalinterfaces"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/cache"
)
// NewInformedWatcherFromFactory watches a Kubernetes namespace for ConfigMap changes.
func NewInformedWatcherFromFactory(sif informers.SharedInformerFactory, namespace string) *InformedWatcher {
return &InformedWatcher{
sif: sif,
informer: sif.Core().V1().ConfigMaps(),
ManualWatcher: configmap.ManualWatcher{
Namespace: namespace,
},
defaults: make(map[string]*corev1.ConfigMap),
}
}
// NewInformedWatcher watches a Kubernetes namespace for ConfigMap changes.
// Optional label requirements allow restricting the list of ConfigMap objects
// that is tracked by the underlying Informer.
func NewInformedWatcher(kc kubernetes.Interface, namespace string, lr ...labels.Requirement) *InformedWatcher {
return NewInformedWatcherFromFactory(informers.NewSharedInformerFactoryWithOptions(
kc,
// We noticed that we're getting updates all the time anyway, due to the
// watches being terminated and re-spawned.
0,
informers.WithNamespace(namespace),
informers.WithTweakListOptions(addLabelRequirementsToListOptions(lr)),
), namespace)
}
// addLabelRequirementsToListOptions returns a function which injects label
// requirements to existing metav1.ListOptions.
func addLabelRequirementsToListOptions(lr []labels.Requirement) internalinterfaces.TweakListOptionsFunc {
if len(lr) == 0 {
return nil
}
return func(lo *metav1.ListOptions) {
sel, err := labels.Parse(lo.LabelSelector)
if err != nil {
panic(fmt.Errorf("could not parse label selector %q: %w", lo.LabelSelector, err))
}
lo.LabelSelector = sel.Add(lr...).String()
}
}
// FilterConfigByLabelExists returns an "exists" label requirement for the
// given label key.
func FilterConfigByLabelExists(labelKey string) (*labels.Requirement, error) {
req, err := labels.NewRequirement(labelKey, selection.Exists, nil)
if err != nil {
return nil, fmt.Errorf("could not construct label requirement: %w", err)
}
return req, nil
}
// InformedWatcher provides an informer-based implementation of Watcher.
type InformedWatcher struct {
sif informers.SharedInformerFactory
informer corev1informers.ConfigMapInformer
started bool
// defaults are the default ConfigMaps to use if the real ones do not exist or are deleted.
defaults map[string]*corev1.ConfigMap
// Embedding this struct allows us to reuse the logic
// of registering and notifying observers. This simplifies the
// InformedWatcher to just setting up the Kubernetes informer.
configmap.ManualWatcher
}
// Asserts that InformedWatcher implements Watcher.
var _ configmap.Watcher = (*InformedWatcher)(nil)
// Asserts that InformedWatcher implements DefaultingWatcher.
var _ configmap.DefaultingWatcher = (*InformedWatcher)(nil)
// WatchWithDefault implements DefaultingWatcher. Adding a default for the configMap being watched means that when
// Start is called, Start will not wait for the add event from the API server.
func (i *InformedWatcher) WatchWithDefault(cm corev1.ConfigMap, o ...configmap.Observer) {
i.defaults[cm.Name] = &cm
i.Lock()
started := i.started
i.Unlock()
if started {
// TODO make both Watch and WatchWithDefault work after the InformedWatcher has started.
// This likely entails changing this to `o(&cm)` and having Watch check started, if it has
// started, then ensuring i.informer.Lister().ConfigMaps(i.Namespace).Get(cmName) exists and
// calling this observer on it. It may require changing Watch and WatchWithDefault to return
// an error.
panic("cannot WatchWithDefault after the InformedWatcher has started")
}
i.Watch(cm.Name, o...)
}
func (i *InformedWatcher) triggerAddEventForDefaultedConfigMaps(addConfigMapEvent func(obj interface{})) {
i.ForEach(func(k string, _ []configmap.Observer) error {
if def, ok := i.defaults[k]; ok {
addConfigMapEvent(def)
}
return nil
})
}
func (i *InformedWatcher) getConfigMapNames() []string {
var configMaps []string
i.ForEach(func(k string, _ []configmap.Observer) error {
configMaps = append(configMaps, k)
return nil
})
return configMaps
}
// Start implements Watcher. Start will wait for all watched resources to exist and for the add event handler to be
// invoked at least once for each before continuing or for the stopCh to be signalled, whichever happens first. If
// the watched resource is defaulted, Start will invoke the add event handler directly and will not wait for a further
// add event from the API server.
func (i *InformedWatcher) Start(stopCh <-chan struct{}) error {
// using the synced callback wrapper around the add event handler will allow the caller
// to wait for the add event to be processed for all configmaps
s := newSyncedCallback(i.getConfigMapNames(), i.addConfigMapEvent)
addConfigMapEvent := func(obj interface{}) {
configMap := obj.(*corev1.ConfigMap)
s.Call(obj, configMap.Name)
}
// Pretend that all the defaulted ConfigMaps were just created. This is done before we start
// the informer to ensure that if a defaulted ConfigMap does exist, then the real value is
// processed after the default one.
i.triggerAddEventForDefaultedConfigMaps(addConfigMapEvent)
if err := i.registerCallbackAndStartInformer(addConfigMapEvent, stopCh); err != nil {
return err
}
// Wait until the shared informer has been synced (WITHOUT holing the mutex, so callbacks happen)
if ok := cache.WaitForCacheSync(stopCh, i.informer.Informer().HasSynced); !ok {
return errors.New("error waiting for ConfigMap informer to sync")
}
if err := i.checkObservedResourcesExist(); err != nil {
return err
}
// Wait until all config maps have been at least initially processed
return s.WaitForAllKeys(stopCh)
}
func (i *InformedWatcher) registerCallbackAndStartInformer(addConfigMapEvent func(obj interface{}), stopCh <-chan struct{}) error {
i.Lock()
defer i.Unlock()
if i.started {
return errors.New("watcher already started")
}
i.started = true
i.informer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: addConfigMapEvent,
UpdateFunc: i.updateConfigMapEvent,
DeleteFunc: i.deleteConfigMapEvent,
})
// Start the shared informer factory (non-blocking).
i.sif.Start(stopCh)
return nil
}
func (i *InformedWatcher) checkObservedResourcesExist() error {
i.RLock()
defer i.RUnlock()
// Check that all objects with Observers exist in our informers.
return i.ForEach(func(k string, _ []configmap.Observer) error {
if _, err := i.informer.Lister().ConfigMaps(i.Namespace).Get(k); err != nil {
if _, ok := i.defaults[k]; ok && k8serrors.IsNotFound(err) {
// It is defaulted, so it is OK that it doesn't exist.
return nil
}
return err
}
return nil
})
}
func (i *InformedWatcher) addConfigMapEvent(obj interface{}) {
configMap := obj.(*corev1.ConfigMap)
i.OnChange(configMap)
}
func (i *InformedWatcher) updateConfigMapEvent(o, n interface{}) {
// Ignore updates that are idempotent. We are seeing those
// periodically.
if equality.Semantic.DeepEqual(o, n) {
return
}
configMap := n.(*corev1.ConfigMap)
i.OnChange(configMap)
}
func (i *InformedWatcher) deleteConfigMapEvent(obj interface{}) {
configMap := obj.(*corev1.ConfigMap)
if def, ok := i.defaults[configMap.Name]; ok {
i.OnChange(def)
}
// If there is no default value, then don't do anything.
}