Shows AWS EKS Fargate auto scaling.

AWS EKS - Fargate Autoscaler

# eksctl version
eksctl version
0.20.0

# kubectl/Kubernetes version
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.3", GitCommit:"2e7996e3e2712684bc73f0dec0200d64eec7fe40", GitTreeState:"clean", BuildDate:"2020-05-21T14:51:23Z", GoVersion:"go1.14.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"16+", GitVersion:"v1.16.8-eks-e16311", GitCommit:"e163110a04dcb2f39c3325af96d019b4925419eb", GitTreeState:"clean", BuildDate:"2020-03-27T22:37:12Z", GoVersion:"go1.13.8", Compiler:"gc", Platform:"linux/amd64"}

AWS_REGION=us-east-2
CLUSTER_NAME=lukaszbudniktest1

# create new cluster with Fargate profile
eksctl create cluster \
  --name $CLUSTER_NAME \
  --version 1.16 \
  --region $AWS_REGION \
  --fargate

# testing autoscaler
# when using Fargate profile we don't need to install Kubernetes autoscaler - AWS will take care of auto scaling

# there will be 2 nodes available and their names will start with "fargate-"
kubectl get nodes

# deploy a test app
cat <<EOF > test-app.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
  labels:
    app: autoscaler-test
spec:
  replicas: 1
  selector:
    matchLabels:
      app: autoscaler-test
      tier: frontend
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: autoscaler-test
        tier: frontend
    spec:
      containers:
      - image: nginx
        name: nginx
EOF
kubectl apply -f test-app.yaml
kubectl get pods

# scale to 30 replicas
kubectl scale --replicas=30 -f test-app.yaml

# wait a moment and check if all replicas are running
kubectl get pods
# the result of the below command may come as a surprise to you
# there will be 30 additional nodes running - each for every replica
kubectl get nodes

# now scale to 60 replicas
kubectl scale --replicas=60 -f test-app.yaml

# again wait a moment and check if all replicas are running
kubectl get pods
# there will be additional 30 nodes running
kubectl get nodes

# in fact you can check that number of all pods equals number of all nodes
kubectl get pods -A | grep Running | wc -l
kubectl get nodes | grep Ready | wc -l

# delete cluster
eksctl delete cluster --region $AWS_REGION --name $CLUSTER_NAME