Horizontal Pod Autoscaling (HPA) 可以根据 CPU 使用率或应用自定义 metrics 自动扩展 Pod 数量（支持 replication controller、deployment 和 replica set ）。
复制 # 创建 pod 和 service
$ kubectl run php-apache --image=k8s.gcr.io/hpa-example --requests=cpu=200m --expose --port=80
service "php-apache" created
deployment "php-apache" created
# 创建 autoscaler
$ kubectl autoscale deployment php-apache --cpu-percent=50 --min=1 --max=10
deployment "php-apache" autoscaled
$ kubectl get hpa
NAME REFERENCE TARGET MINPODS MAXPODS REPLICAS AGE
php-apache Deployment/php-apache/scale 0% / 50% 1 10 1 18s
# 增加负载
$ kubectl run -i --tty load-generator --image=busybox /bin/sh
Hit enter for command prompt
$ while true ; do wget -q -O- http://php-apache.default.svc.cluster.local ; done
# 过一会就可以看到负载升高了
$ kubectl get hpa
NAME REFERENCE TARGET CURRENT MINPODS MAXPODS REPLICAS AGE
php-apache Deployment/php-apache/scale 305% / 50% 305% 1 10 1 3m
# autoscaler 将这个 deployment 扩展为 7 个 pod
$ kubectl get deployment php-apache
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
php-apache 7 7 7 7 19m
# 删除刚才创建的负载增加 pod 后会发现负载降低，并且 pod 数量也自动降回 1 个
$ kubectl get hpa
NAME REFERENCE TARGET MINPODS MAXPODS REPLICAS AGE
php-apache Deployment/php-apache/scale 0% / 50% 1 10 1 11m
$ kubectl get deployment php-apache
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
php-apache 1 1 1 1 27m 注：可以参考 k8s.io/metics 开发自定义的 metrics API server。
复制 apiVersion : autoscaling/v1
kind : HorizontalPodAutoscaler
metadata :
name : php-apache
namespace : default
spec :
scaleTargetRef :
apiVersion : apps/v1beta1
kind : Deployment
name : php-apache
minReplicas : 1
maxReplicas : 10
metrics :
- type : Resource
resource :
name : cpu
targetAverageUtilization : 50
- type : Pods
pods :
metricName : packets-per-second
targetAverageValue : 1k
- type : Object
object :
metricName : requests-per-second
target :
apiVersion : extensions/v1beta1
kind : Ingress
name : main-route
targetValue : 10k
status :
observedGeneration : 1
lastScaleTime : <some-time>
currentReplicas : 1
desiredReplicas : 1
currentMetrics :
- type : Resource
resource :
name : cpu
currentAverageUtilization : 0
currentAverageValue : 0
复制 $ kubectl describe hpa cm-test
Name: cm-test
Namespace: prom
Labels: < non e >
Annotations: < non e >
CreationTimestamp: Fri, 16 Jun 2017 18:09:22 +0000
Reference: ReplicationController/cm-test
Metrics: (current / target )
"http_requests" on pods: 66m / 500m
Min replicas: 1
Max replicas: 4
ReplicationController pods: 1 current / 1 desired
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True ReadyForNewScale the last scale time was sufficiently old as to warrant a new scale
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from pods metric http_requests
ScalingLimited False DesiredWithinRange the desired replica count is within the acceptable range
Events: 