How to Horizontal Autoscaler a Kubernetes Deployment - kubernetes

Question

EDIT:
SOLUTION: I forgot to add target_cpu_utilization_percentage to autoscaler.tf file
I want a web-service in Python (or other language) running on Kubernetes but with auto scaling.
I created a Deployment and a Horizontal Autoscaler but is not working.
I'm using Terraform to configure Kubernetes.
I have this files:
Deployments.tf
resource "kubernetes_deployment" "rui-test" {
metadata {
name = "rui-test"
labels {
app = "rui-test"
}
}
spec {
strategy = {
type = "RollingUpdate"
rolling_update = {
max_unavailable = "26%" # This is not working
}
}
selector = {
match_labels = {
app = "rui-test"
}
}
template = {
metadata = {
labels = {
app = "rui-test"
}
}
spec = {
container {
name = "python-test1"
image = "***************************"
}
}
}
}
}
Autoscaler.tf
resource "kubernetes_horizontal_pod_autoscaler" "test-rui" {
metadata {
name = "test-rui"
}
spec {
max_replicas = 10 # THIS IS NOT WORKING
min_replicas = 3 # THIS IS NOT WORKING
scale_target_ref {
kind = "Deployment"
name = "test-rui" # Name of deployment
}
}
}
Service.tf
resource "kubernetes_service" "rui-test" {
metadata {
name = "rui-test"
labels {
app = "rui-test"
}
}
spec {
selector {
app = "rui-test"
}
type = "LoadBalancer" # Use 'cluster_ip = "None"' or 'type = "LoadBalancer"'
port {
name = "http"
port = 8080
}
}
}
When I run kubectl get hpa I see this:
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
rui-test Deployment/rui-test <unknown>/80% 1 3 1 1h
Instead of:
rui-test Deployment/rui-test <unknown>/79% 3 10 1 1h
That is what I want.
But if I run kubectl autoscale deployment rui-test --min=3 --max=10 --cpu-percent=81 I see this:
Error from server (AlreadyExists): horizontalpodautoscalers.autoscaling "rui-test" already exists
In kubernetes appear this

Answer 1

You are missing the metrics server. Kubernetes needs to determine current CPU/Memory usage so that it can autoscale up and down.
One way to know if you have the metrics server installed is to run:
$ kubectl top node
$ kubectl top pod

Answer 2

The Horizontal Pod AutoScaler is dependent on resource limits being configured for your Deployment.
From the documentation:
Please note that if some of the pod’s containers do not have the relevant resource request set, CPU utilization for the pod will not be defined and the autoscaler will not take any action for that metric.