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Kubernetes

Kubernetes (K8s) adalah platform orkestrasi container open-source untuk mengotomatisasi deployment, scaling, dan manajemen aplikasi berbasis container.

Arsitektur Kubernetes​

Control Plane

  • API Server
  • Etcd
  • Scheduler
  • Controller Manager

Worker Node

  • Kubelet
  • Kube-proxy
  • Container Runtime (Docker, containerd)

Requirements​

Hardware Control Plane:

  • 2–4 CPU
  • 4–8GB RAM
  • 40GB Storage

Worker Node:

  • 2 CPU
  • 4GB RAM
  • 20GB Storage

Software

  • OS: Ubuntu 20.04/22.04 atau setara
  • Swap: Disabled
  • Internet untuk pull image

Network

  • Port control-plane: 6443, 2379–2380, 10250, 10251, 10252
  • Port worker: 10250, 30000–32767

Instalasi Kubernetes (kubeadm)​

Step 1 – Update Server

sudo apt update && sudo apt upgrade -y

Step 2 – Disable Swap

sudo swapoff -a
sed -i '/ swap / s/^/#/' /etc/fstab

Step 3 – Install containerd

sudo apt install -y containerd
sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml
sudo systemctl restart containerd
sudo systemctl enable containerd

Step 4 – Install kubeadm, kubelet, kubectl

sudo apt install -y apt-transport-https ca-certificates curl
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo systemctl enable kubelet

5 - Inisialisasi Master Node

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Copy config:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Install CNI (Flannel)

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Join Worker Node

kubeadm join <IP-MASTER>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

erifikasi Cluster*

kubectl get nodes
kubectl get pods -A

Best Practice

  • Minimal 3 control-plane untuk HA
  • Gunakan load balancer
  • Gunakan monitoring: Prometheus + Grafana
  • Gunakan private registry

Alternatif Kubernetes On-Prem​

  • RKE / RKE2
  • K3s
  • MicroK8s
  • OpenShift

Diagram Arsitektur Kubernetes (Sederhana)​

                 +-----------------------+
                 |     Control Plane     |
                 |------------------------|
                 | API Server            |
                 | Scheduler             |
                 | Controller Manager    |
                 | Etcd (storage)        |
                 +-----------+-----------+
                             |
         --------------------------------------------
         |                    |                     |
+--------+-------+   +--------+-------+    +--------+-------+
|   Worker 1     |   |   Worker 2     |    |   Worker 3     |
|----------------|   |----------------|    |----------------|
| Kubelet        |   | Kubelet        |    | Kubelet        |
| Kube-proxy     |   | Kube-proxy     |    | Kube-proxy     |
| Containerd     |   | Containerd     |    | Containerd     |
+----------------+   +----------------+    +----------------+

Contoh Topologi High Availability (HA)​

                 +-------------------------------+
                 |      External Load Balancer   |
                 |   IP: 10.10.10.100:6443       |
                 +-------------------------------+
                         |        |        |
                ---------|--------|--------|------
                |                 |               |
        +-------+------+  +-------+------+  +-------+------+
        | ControlPlane1 |  | ControlPlane2 |  | ControlPlane3 |
        +--------------+  +--------------+  +--------------+
                |                 |               |
        ------------------------------------------------------
                         Cluster Network
        ------------------------------------------------------
                |                 |               |
        +-------+------+  +-------+------+  +-------+------+
        | WorkerNode1  |  | WorkerNode2  |  | WorkerNode3  |
        +--------------+  +--------------+  +--------------+

Contoh Deployment YAML (Nginx)​

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

Contoh Service YAML (LoadBalancer)​

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: LoadBalancer
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

Contoh Ingress YAML​

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
spec:
  rules:
  - host: nginx.local
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port:
              number: 80

Menambah Node Baru ke Cluster​

** 1. Buat token baru

kubeadm token create --print-join-command

** 2. Jalankan perintah di worker node

kubeadm join <IP-LB>:6443 --token <token> --discovery-token-ca-cert-hash <hash>

Monitoring Kubernetes (Contoh: Prometheus + Grafana)​

** Deploy Prometheus + Grafana via Helm

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm repo add grafana https://grafana.github.io/helm-charts
helm repo update

helm install prometheus prometheus-community/kube-prometheus-stack
helm install grafana grafana/grafana

Addons Rekomendasi​

  • Metrics Server: untuk HPA
  • Ingress Controller (Nginx/Traefik)
  • Longhorn / Ceph untuk storage
  • Loki untuk logging
  • Cert-Manager untuk TLS otomatis