K3s Kubernetes-Installation: Leichte Container-Orchestrierung

# Mindestanforderungen
# CPU: 1 Kern
# RAM: 512MB (empfohlen: 1GB+)
# Disk: 5GB
# OS: Ubuntu 20.04+, Debian 11+, CentOS 8+

# System aktualisieren
apt update && apt upgrade -y

# Benötigte Tools installieren
apt install -y curl wget

# K3s installieren (Server-Modus)
curl -sfL https://get.k3s.io | sh -

# Service-Status nach Installation prüfen
systemctl status k3s

# Cluster-Status prüfen
kubectl get nodes

# Alle Pods auflisten
kubectl get pods -A

# Kubeconfig für kubectl kopieren
mkdir -p ~/.kube
cp /etc/rancher/k3s/k3s.yaml ~/.kube/config
chmod 600 ~/.kube/config

# KUBECONFIG-Umgebungsvariable setzen
export KUBECONFIG=~/.kube/config
echo 'export KUBECONFIG=~/.kube/config' >> ~/.bashrc

# Cluster-Informationen anzeigen
kubectl cluster-info

# Master-Node installieren und Token speichern
curl -sfL https://get.k3s.io | sh -

# Node-Token abrufen (für Worker-Nodes benötigt)
cat /var/lib/rancher/k3s/server/node-token

# Worker-Node mit Master verbinden
curl -sfL https://get.k3s.io | K3S_URL=https://MASTER_IP:6443 K3S_TOKEN=NODE_TOKEN sh -

# Auf Master prüfen, ob Worker beigetreten ist
kubectl get nodes

# Nodes auflisten
kubectl get nodes
kubectl get nodes -o wide

# Pods auflisten
kubectl get pods
kubectl get pods -n kube-system
kubectl get pods -A

# Deployments auflisten
kubectl get deployments

# Services auflisten
kubectl get services

# Ressourcendetails anzeigen
kubectl describe pod POD_NAME
kubectl describe node NODE_NAME

# Pod-Logs anzeigen
kubectl logs POD_NAME
kubectl logs -f POD_NAME

# Befehl in Pod ausführen
kubectl exec -it POD_NAME -- /bin/bash

# nginx-deployment.yaml
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:1.25
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

# Deployment anwenden
kubectl apply -f nginx-deployment.yaml

# Deployment-Status prüfen
kubectl get deployments
kubectl rollout status deployment/nginx-deployment

# nginx-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 30080
  type: NodePort

kubectl apply -f nginx-service.yaml
kubectl get services
# Zugriff: http://SERVER_IP:30080

# Helm installieren
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Bitnami-Repository hinzufügen
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

# WordPress installieren
helm install my-wordpress bitnami/wordpress \
  --set wordpressUsername=admin \
  --set wordpressPassword=StarkesPasswort123! \
  --set service.type=NodePort

# Installierte Charts auflisten
helm list

# Chart entfernen
helm uninstall my-wordpress

# K3s aktualisieren
curl -sfL https://get.k3s.io | INSTALL_K3S_VERSION=v1.28.0+k3s1 sh -

# K3s-Service verwalten
systemctl stop k3s
systemctl start k3s
systemctl restart k3s

# K3s-Logs anzeigen
journalctl -u k3s -f

# K3s deinstallieren
/usr/local/bin/k3s-uninstall.sh