Testing HPAs with kubectl
This document describes how to check the status of your HPAs after scaling them up or down with your load testing tool. For information on how to check the status from the Rancher UI (at least version 2.3.x), refer to Managing HPAs with the Rancher UI.
For HPA to work correctly, service deployments should have resources request definitions for containers. Follow this hello-world example to test if HPA is working correctly.
Configure
kubectlto connect to your Kubernetes cluster.Copy the
hello-worlddeployment manifest below.Hello World Manifest
apiVersion: apps/v1beta2
kind: Deployment
metadata:
labels:
app: hello-world
name: hello-world
namespace: default
spec:
replicas: 1
selector:
matchLabels:
app: hello-world
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 0
type: RollingUpdate
template:
metadata:
labels:
app: hello-world
spec:
containers:
- image: rancher/hello-world
imagePullPolicy: Always
name: hello-world
resources:
requests:
cpu: 500m
memory: 64Mi
ports:
- containerPort: 80
protocol: TCP
restartPolicy: Always
---
apiVersion: v1
kind: Service
metadata:
name: hello-world
namespace: default
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
app: hello-worldDeploy it to your cluster.
# kubectl create -f <HELLO_WORLD_MANIFEST>Copy one of the HPAs below based on the metric type you're using:
Hello World HPA: Resource Metrics
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: hello-world
namespace: default
spec:
scaleTargetRef:
apiVersion: extensions/v1beta1
kind: Deployment
name: hello-world
minReplicas: 1
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
targetAverageUtilization: 50
- type: Resource
resource:
name: memory
targetAverageValue: 1000MiHello World HPA: Custom Metrics
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: hello-world
namespace: default
spec:
scaleTargetRef:
apiVersion: extensions/v1beta1
kind: Deployment
name: hello-world
minReplicas: 1
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
targetAverageUtilization: 50
- type: Resource
resource:
name: memory
targetAverageValue: 100Mi
- type: Pods
pods:
metricName: cpu_system
targetAverageValue: 20mView the HPA info and description. Confirm that metric data is shown.
Resource Metrics
- Enter the following commands.
# kubectl get hpa
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
hello-world Deployment/hello-world 1253376 / 100Mi, 0% / 50% 1 10 1 6m
# kubectl describe hpa
Name: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Mon, 23 Jul 2018 20:21:16 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 1253376 / 100Mi
resource cpu on pods (as a percentage of request): 0% (0) / 50%
Min replicas: 1
Max replicas: 10
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 memory resource
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events: <none>
Custom Metrics
- Enter the following command.You should receive the output that follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Tue, 24 Jul 2018 18:36:28 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 3514368 / 100Mi
"cpu_system" on pods: 0 / 20m
resource cpu on pods (as a percentage of request): 0% (0) / 50%
Min replicas: 1
Max replicas: 10
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 memory resource
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events: <none>
- Enter the following commands.
Generate a load for the service to test that your pods autoscale as intended. You can use any load-testing tool (Hey, Gatling, etc.), but we're using Hey.
Test that pod autoscaling works as intended.
To Test Autoscaling Using Resource Metrics:Upscale to 2 Pods: CPU Usage Up to Target
Use your load testing tool to scale up to two pods based on CPU Usage.
- View your HPA.You should receive output similar to what follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Mon, 23 Jul 2018 22:22:04 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 10928128 / 100Mi
resource cpu on pods (as a percentage of request): 56% (280m) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 2
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 13s horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target - Enter the following command to confirm you've scaled to two pods.You should receive output similar to what follows:
# kubectl get podsNAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-k8ph2 1/1 Running 0 1m
hello-world-54764dfbf8-q6l4v 1/1 Running 0 3h
Upscale to 3 pods: CPU Usage Up to Target
Use your load testing tool to upscale to 3 pods based on CPU usage with
horizontal-pod-autoscaler-upscale-delayset to 3 minutes.- Enter the following command.You should receive output similar to what follows
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Mon, 23 Jul 2018 22:22:04 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 9424896 / 100Mi
resource cpu on pods (as a percentage of request): 66% (333m) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 3
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 4m horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 16s horizontal-pod-autoscaler New size: 3; reason: cpu resource utilization (percentage of request) above target - Enter the following command to confirm three pods are running.You should receive output similar to what follows.
# kubectl get podsNAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-f46kh 0/1 Running 0 1m
hello-world-54764dfbf8-k8ph2 1/1 Running 0 5m
hello-world-54764dfbf8-q6l4v 1/1 Running 0 3h
Downscale to 1 Pod: All Metrics Below Target
Use your load testing to scale down to 1 pod when all metrics are below target for
horizontal-pod-autoscaler-downscale-delay(5 minutes by default).- Enter the following command.You should receive output similar to what follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Mon, 23 Jul 2018 22:22:04 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 10070016 / 100Mi
resource cpu on pods (as a percentage of request): 0% (0) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 1
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from memory resource
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 10m horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 6m horizontal-pod-autoscaler New size: 3; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 1s horizontal-pod-autoscaler New size: 1; reason: All metrics below target
To Test Autoscaling Using Custom Metrics:
Upscale to 2 Pods: CPU Usage Up to Target
Use your load testing tool to upscale two pods based on CPU usage.
- Enter the following command.You should receive output similar to what follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Tue, 24 Jul 2018 18:01:11 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 8159232 / 100Mi
"cpu_system" on pods: 7m / 20m
resource cpu on pods (as a percentage of request): 64% (321m) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 2
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 16s horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target - Enter the following command to confirm two pods are running.You should receive output similar to what follows.
# kubectl get podsNAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-5pfdr 1/1 Running 0 3s
hello-world-54764dfbf8-q6l82 1/1 Running 0 6h
Upscale to 3 Pods: CPU Usage Up to Target
Use your load testing tool to scale up to three pods when the cpu_system usage limit is up to target.
- Enter the following command.You should receive output similar to what follows:
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Tue, 24 Jul 2018 18:01:11 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 8374272 / 100Mi
"cpu_system" on pods: 27m / 20m
resource cpu on pods (as a percentage of request): 71% (357m) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 3
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 3m horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 3s horizontal-pod-autoscaler New size: 3; reason: pods metric cpu_system above target - Enter the following command to confirm three pods are running.You should receive output similar to what follows:
# kubectl get pods# kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-5pfdr 1/1 Running 0 3m
hello-world-54764dfbf8-m2hrl 1/1 Running 0 1s
hello-world-54764dfbf8-q6l82 1/1 Running 0 6h
Upscale to 4 Pods: CPU Usage Up to Target
Use your load testing tool to upscale to four pods based on CPU usage.
horizontal-pod-autoscaler-upscale-delayis set to three minutes by default.- Enter the following command.You should receive output similar to what follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Tue, 24 Jul 2018 18:01:11 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 8374272 / 100Mi
"cpu_system" on pods: 27m / 20m
resource cpu on pods (as a percentage of request): 71% (357m) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 3
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from cpu resource utilization (percentage of request)
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 5m horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 3m horizontal-pod-autoscaler New size: 3; reason: pods metric cpu_system above target
Normal SuccessfulRescale 4s horizontal-pod-autoscaler New size: 4; reason: cpu resource utilization (percentage of request) above target - Enter the following command to confirm four pods are running.You should receive output similar to what follows.
# kubectl get podsNAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-2p9xb 1/1 Running 0 5m
hello-world-54764dfbf8-5pfdr 1/1 Running 0 2m
hello-world-54764dfbf8-m2hrl 1/1 Running 0 1s
hello-world-54764dfbf8-q6l82 1/1 Running 0 6h
Downscale to 1 Pod: All Metrics Below Target
Use your load testing tool to scale down to one pod when all metrics below target for
horizontal-pod-autoscaler-downscale-delay.- Enter the following command.You should receive similar output to what follows.
# kubectl describe hpaName: hello-world
Namespace: default
Labels: <none>
Annotations: <none>
CreationTimestamp: Tue, 24 Jul 2018 18:01:11 +0200
Reference: Deployment/hello-world
Metrics: ( current / target )
resource memory on pods: 8101888 / 100Mi
"cpu_system" on pods: 8m / 20m
resource cpu on pods (as a percentage of request): 0% (0) / 50%
Min replicas: 1
Max replicas: 10
Conditions:
Type Status Reason Message
---- ------ ------ -------
AbleToScale True SucceededRescale the HPA controller was able to update the target scale to 1
ScalingActive True ValidMetricFound the HPA was able to successfully calculate a replica count from memory resource
ScalingLimited False DesiredWithinRange the desired count is within the acceptable range
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulRescale 10m horizontal-pod-autoscaler New size: 2; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 8m horizontal-pod-autoscaler New size: 3; reason: pods metric cpu_system above target
Normal SuccessfulRescale 5m horizontal-pod-autoscaler New size: 4; reason: cpu resource utilization (percentage of request) above target
Normal SuccessfulRescale 13s horizontal-pod-autoscaler New size: 1; reason: All metrics below target - Enter the following command to confirm a single pods is running.You should receive output similar to what follows.
# kubectl get podsNAME READY STATUS RESTARTS AGE
hello-world-54764dfbf8-q6l82 1/1 Running 0 6h
- View your HPA.