Kubernetes Autoscaling - kubernetes

Question

I have Kubernetes v1.12.1 installed on my cluster.
I downloaded the metrics-server from the following repo:
https://github.com/kubernetes-incubator/metrics-server
and then run the following command:
kubectl create -f metrics-server/deploy/1.8+/
and then I tried autoscaling a deployment using:
kubectl autoscale deployment example-app-tier --min 1 --max 3 --cpu-percent 70 --spacename example
but the targets here shows unkown/70%
kubectl get hpa --spacename example
NAMESPACE NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
example example-app-tier Deployment/example-app-tier <unknown>/70% 1 3 1 3h35m
and when I try running the kubectl top nodes or pods I get an error saying:
error: Metrics not available for pod default/pi-ss8j6, age: 282h48m5.334137739s
So I'm looking for any tutorial that helps me step by step enabling autoscaling using metrics-server or Prometheus (and not Heapster as it is deprecated and will not be supported anymore)
Thank you!

Answer 1

you need to register your metrics server with API server and make sure they communicate.
https://github.com/kubernetes/kubernetes/issues/59438
If it is done already , you need to check the help for the kubectl top command in your version of k8s , the command may default to use heapster , and you may need to tell it to use the new service instead.
https://github.com/kubernetes/kubernetes/pull/56206
from the help command it looks like it is not yet ported to new metric server and still looking for heapster by default.
C02W84XMHTD5:tmp iahmad$ kubectl top node --help
Display Resource (CPU/Memory/Storage) usage of nodes.
The top-node command allows you to see the resource consumption of nodes.
Aliases:
node, nodes, no
Examples:
# Show metrics for all nodes
kubectl top node
# Show metrics for a given node
kubectl top node NODE_NAME
Options:
--heapster-namespace='kube-system': Namespace Heapster service is located in
--heapster-port='': Port name in service to use
--heapster-scheme='http': Scheme (http or https) to connect to Heapster as
--heapster-service='heapster': Name of Heapster service
-l, --selector='': Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l
key1=value1,key2=value2)
Usage:
kubectl top node [NAME | -l label] [options]
Use "kubectl options" for a list of global command-line options (applies to all commands).
note: I am using 1.10 , maybe in your version , the options are different