Kubernetes

This guide provides step-by-step instructions for setting up a Kubernetes cluster using kind, configuring multiple nodes, and installing the Metrics Server.

Prerequisites

Ensure you have the following installed:

Docker (required for running kind clusters).
Kind (Kubernetes in Docker).
Kubectl (Kubernetes command-line tool).

Additionally, ensure that Kubernetes tools are enabled in your environment by setting the following variable in your .env file:

# Enable Kubernetes tool
ENABLE_KUBERNETES=true

1. Creating a Kubernetes Cluster with Multiple Nodes

We will create a Kubernetes cluster using kind with one control plane node and two worker nodes.

Define the Cluster Configuration

Create a configuration file named kind-config.yaml with the following content:

cat > kind-config.yaml <<EOF
# three node (two workers) cluster config
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
  kubeadmConfigPatches:
    - |
      kind: KubeletConfiguration
      apiVersion: kubelet.config.k8s.io/v1beta1
      kubeReserved:
        cpu: "250m"
        memory: "256Mi"
      systemReserved:
        cpu: "500m"
        memory: "512Mi"
      evictionHard:
        memory.available: "200Mi"
- role: worker
- role: worker
EOF

Create the Cluster

Run the following command to create the Kubernetes cluster:

kind create cluster --name k8s-playground --config kind-config.yaml

This will provision a cluster named k8s-playground with the specified node configuration.

2. Installing the Metrics Server

The Metrics Server is required for gathering resource utilization metrics like CPU and memory usage. It is essential for features such as Horizontal Pod Autoscaling.

Deploy the Metrics Server

Run the following command to install the Metrics Server:

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.7.2/components.yaml

Disable TLS Verification (For Local Development)

In local environments, Kubernetes nodes might not have valid certificates. To disable TLS verification, patch the deployment:

kubectl patch -n kube-system deployment metrics-server --type=json \
  -p '[{"op":"add","path":"/spec/template/spec/containers/0/args/-","value":"--kubelet-insecure-tls"}]'

This allows the Metrics Server to communicate with kubelets that use self-signed certificates.

3. Verifying the Setup

After completing the setup, verify that the cluster is running correctly:

Check the Cluster Nodes

kubectl get nodes

Expected output:

NAME                           STATUS   ROLES           AGE     VERSION
k8s-playground-control-plane   Ready    control-plane   Xs      vX.Y.Z
k8s-playground-worker          Ready    worker          Xs      vX.Y.Z
k8s-playground-worker2         Ready    worker          Xs      vX.Y.Z

Check Metrics Server Status

kubectl get deployment -n kube-system metrics-server