-
Notifications
You must be signed in to change notification settings - Fork 1
/
replica_calculator.go
283 lines (234 loc) · 11.2 KB
/
replica_calculator.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
/*
Copyright 2016 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 podautoscaler
import (
"fmt"
"math"
"time"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/kubernetes/pkg/api/v1"
podutil "k8s.io/kubernetes/pkg/api/v1/pod"
autoscaling "k8s.io/kubernetes/pkg/apis/autoscaling/v2alpha1"
v1coreclient "k8s.io/kubernetes/pkg/client/clientset_generated/clientset/typed/core/v1"
metricsclient "k8s.io/kubernetes/pkg/controller/podautoscaler/metrics"
)
type ReplicaCalculator struct {
metricsClient metricsclient.MetricsClient
podsGetter v1coreclient.PodsGetter
}
func NewReplicaCalculator(metricsClient metricsclient.MetricsClient, podsGetter v1coreclient.PodsGetter) *ReplicaCalculator {
return &ReplicaCalculator{
metricsClient: metricsClient,
podsGetter: podsGetter,
}
}
// GetResourceReplicas calculates the desired replica count based on a target resource utilization percentage
// of the given resource for pods matching the given selector in the given namespace, and the current replica count
func (c *ReplicaCalculator) GetResourceReplicas(currentReplicas int32, targetUtilization int32, resource v1.ResourceName, namespace string, selector labels.Selector) (replicaCount int32, utilization int32, rawUtilization int64, timestamp time.Time, err error) {
metrics, timestamp, err := c.metricsClient.GetResourceMetric(resource, namespace, selector)
if err != nil {
return 0, 0, 0, time.Time{}, fmt.Errorf("unable to get metrics for resource %s: %v", resource, err)
}
podList, err := c.podsGetter.Pods(namespace).List(metav1.ListOptions{LabelSelector: selector.String()})
if err != nil {
return 0, 0, 0, time.Time{}, fmt.Errorf("unable to get pods while calculating replica count: %v", err)
}
itemsLen := len(podList.Items)
if itemsLen == 0 {
return 0, 0, 0, time.Time{}, fmt.Errorf("no pods returned by selector while calculating replica count")
}
requests := make(map[string]int64, itemsLen)
readyPodCount := 0
unreadyPods := sets.NewString()
missingPods := sets.NewString()
for _, pod := range podList.Items {
podSum := int64(0)
for _, container := range pod.Spec.Containers {
if containerRequest, ok := container.Resources.Requests[resource]; ok {
podSum += containerRequest.MilliValue()
} else {
return 0, 0, 0, time.Time{}, fmt.Errorf("missing request for %s on container %s in pod %s/%s", resource, container.Name, namespace, pod.Name)
}
}
requests[pod.Name] = podSum
if pod.Status.Phase != v1.PodRunning || !podutil.IsPodReady(&pod) {
// save this pod name for later, but pretend it doesn't exist for now
unreadyPods.Insert(pod.Name)
delete(metrics, pod.Name)
continue
}
if _, found := metrics[pod.Name]; !found {
// save this pod name for later, but pretend it doesn't exist for now
missingPods.Insert(pod.Name)
continue
}
readyPodCount++
}
if len(metrics) == 0 {
return 0, 0, 0, time.Time{}, fmt.Errorf("did not receive metrics for any ready pods")
}
usageRatio, utilization, rawUtilization, err := metricsclient.GetResourceUtilizationRatio(metrics, requests, targetUtilization)
if err != nil {
return 0, 0, 0, time.Time{}, err
}
rebalanceUnready := len(unreadyPods) > 0 && usageRatio > 1.0
if !rebalanceUnready && len(missingPods) == 0 {
if math.Abs(1.0-usageRatio) <= tolerance {
// return the current replicas if the change would be too small
return currentReplicas, utilization, rawUtilization, timestamp, nil
}
// if we don't have any unready or missing pods, we can calculate the new replica count now
return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, rawUtilization, timestamp, nil
}
if len(missingPods) > 0 {
if usageRatio < 1.0 {
// on a scale-down, treat missing pods as using 100% of the resource request
for podName := range missingPods {
metrics[podName] = requests[podName]
}
} else if usageRatio > 1.0 {
// on a scale-up, treat missing pods as using 0% of the resource request
for podName := range missingPods {
metrics[podName] = 0
}
}
}
if rebalanceUnready {
// on a scale-up, treat unready pods as using 0% of the resource request
for podName := range unreadyPods {
metrics[podName] = 0
}
}
// re-run the utilization calculation with our new numbers
newUsageRatio, _, _, err := metricsclient.GetResourceUtilizationRatio(metrics, requests, targetUtilization)
if err != nil {
return 0, utilization, rawUtilization, time.Time{}, err
}
if math.Abs(1.0-newUsageRatio) <= tolerance || (usageRatio < 1.0 && newUsageRatio > 1.0) || (usageRatio > 1.0 && newUsageRatio < 1.0) {
// return the current replicas if the change would be too small,
// or if the new usage ratio would cause a change in scale direction
return currentReplicas, utilization, rawUtilization, timestamp, nil
}
// return the result, where the number of replicas considered is
// however many replicas factored into our calculation
return int32(math.Ceil(newUsageRatio * float64(len(metrics)))), utilization, rawUtilization, timestamp, nil
}
// GetRawResourceReplicas calculates the desired replica count based on a target resource utilization (as a raw milli-value)
// for pods matching the given selector in the given namespace, and the current replica count
func (c *ReplicaCalculator) GetRawResourceReplicas(currentReplicas int32, targetUtilization int64, resource v1.ResourceName, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
metrics, timestamp, err := c.metricsClient.GetResourceMetric(resource, namespace, selector)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to get metrics for resource %s: %v", resource, err)
}
replicaCount, utilization, err = c.calcPlainMetricReplicas(metrics, currentReplicas, targetUtilization, namespace, selector)
return replicaCount, utilization, timestamp, err
}
// GetMetricReplicas calculates the desired replica count based on a target metric utilization
// (as a milli-value) for pods matching the given selector in the given namespace, and the
// current replica count
func (c *ReplicaCalculator) GetMetricReplicas(currentReplicas int32, targetUtilization int64, metricName string, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
metrics, timestamp, err := c.metricsClient.GetRawMetric(metricName, namespace, selector)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to get metric %s: %v", metricName, err)
}
replicaCount, utilization, err = c.calcPlainMetricReplicas(metrics, currentReplicas, targetUtilization, namespace, selector)
return replicaCount, utilization, timestamp, err
}
// calcPlainMetricReplicas calculates the desired replicas for plain (i.e. non-utilization percentage) metrics.
func (c *ReplicaCalculator) calcPlainMetricReplicas(metrics metricsclient.PodMetricsInfo, currentReplicas int32, targetUtilization int64, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, err error) {
podList, err := c.podsGetter.Pods(namespace).List(metav1.ListOptions{LabelSelector: selector.String()})
if err != nil {
return 0, 0, fmt.Errorf("unable to get pods while calculating replica count: %v", err)
}
if len(podList.Items) == 0 {
return 0, 0, fmt.Errorf("no pods returned by selector while calculating replica count")
}
readyPodCount := 0
unreadyPods := sets.NewString()
missingPods := sets.NewString()
for _, pod := range podList.Items {
if pod.Status.Phase != v1.PodRunning || !podutil.IsPodReady(&pod) {
// save this pod name for later, but pretend it doesn't exist for now
unreadyPods.Insert(pod.Name)
delete(metrics, pod.Name)
continue
}
if _, found := metrics[pod.Name]; !found {
// save this pod name for later, but pretend it doesn't exist for now
missingPods.Insert(pod.Name)
continue
}
readyPodCount++
}
if len(metrics) == 0 {
return 0, 0, fmt.Errorf("did not receive metrics for any ready pods")
}
usageRatio, utilization := metricsclient.GetMetricUtilizationRatio(metrics, targetUtilization)
rebalanceUnready := len(unreadyPods) > 0 && usageRatio > 1.0
if !rebalanceUnready && len(missingPods) == 0 {
if math.Abs(1.0-usageRatio) <= tolerance {
// return the current replicas if the change would be too small
return currentReplicas, utilization, nil
}
// if we don't have any unready or missing pods, we can calculate the new replica count now
return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, nil
}
if len(missingPods) > 0 {
if usageRatio < 1.0 {
// on a scale-down, treat missing pods as using 100% of the resource request
for podName := range missingPods {
metrics[podName] = targetUtilization
}
} else {
// on a scale-up, treat missing pods as using 0% of the resource request
for podName := range missingPods {
metrics[podName] = 0
}
}
}
if rebalanceUnready {
// on a scale-up, treat unready pods as using 0% of the resource request
for podName := range unreadyPods {
metrics[podName] = 0
}
}
// re-run the utilization calculation with our new numbers
newUsageRatio, _ := metricsclient.GetMetricUtilizationRatio(metrics, targetUtilization)
if err != nil {
return 0, utilization, err
}
if math.Abs(1.0-newUsageRatio) <= tolerance || (usageRatio < 1.0 && newUsageRatio > 1.0) || (usageRatio > 1.0 && newUsageRatio < 1.0) {
// return the current replicas if the change would be too small,
// or if the new usage ratio would cause a change in scale direction
return currentReplicas, utilization, nil
}
// return the result, where the number of replicas considered is
// however many replicas factored into our calculation
return int32(math.Ceil(newUsageRatio * float64(len(metrics)))), utilization, nil
}
// GetObjectMetricReplicas calculates the desired replica count based on a target metric utilization (as a milli-value)
// for the given object in the given namespace, and the current replica count.
func (c *ReplicaCalculator) GetObjectMetricReplicas(currentReplicas int32, targetUtilization int64, metricName string, namespace string, objectRef *autoscaling.CrossVersionObjectReference) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
utilization, timestamp, err = c.metricsClient.GetObjectMetric(metricName, namespace, objectRef)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to get metric %s: %v on %s %s/%s", metricName, objectRef.Kind, namespace, objectRef.Name, err)
}
usageRatio := float64(utilization) / float64(targetUtilization)
if math.Abs(1.0-usageRatio) <= tolerance {
// return the current replicas if the change would be too small
return currentReplicas, utilization, timestamp, nil
}
return int32(math.Ceil(usageRatio * float64(currentReplicas))), utilization, timestamp, nil
}