Volumes, PV, PVC, StorageClass і межі single-node storage

kubectl create namespace k8s-m09
cat > /tmp/k8s-m09-emptydir.yaml <<'EOF'
apiVersion: v1
kind: Pod
metadata: {name: shared, namespace: k8s-m09}
spec:
  containers:
  - name: writer
    image: busybox:1.37
    command: ["sh", "-c", "while true; do date -Iseconds >> /shared/events; sleep 5; done"]
    volumeMounts: [{name: shared, mountPath: /shared}]
  - name: reader
    image: busybox:1.37
    command: ["sh", "-c", "tail -F /shared/events"]
    volumeMounts: [{name: shared, mountPath: /shared}]
  volumes:
  - name: shared
    emptyDir: {}
EOF
kubectl apply --dry-run=server -f /tmp/k8s-m09-emptydir.yaml
kubectl apply -f /tmp/k8s-m09-emptydir.yaml
kubectl -n k8s-m09 wait --for=condition=Ready pod/shared --timeout=120s
kubectl -n k8s-m09 logs shared -c reader --tail=5
kubectl -n k8s-m09 exec shared -c writer -- kill 1
kubectl -n k8s-m09 wait --for=jsonpath='{.status.containerStatuses[0].restartCount}'=1 pod/shared --timeout=120s
kubectl -n k8s-m09 exec shared -c reader -- tail -3 /shared/events

sudo install -d -m 0777 /var/lib/k8s-course/m09
cat > /tmp/k8s-m09-storage.yaml <<'EOF'
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata: {name: manual-local}
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: v1
kind: PersistentVolume
metadata: {name: k8s-m09-data}
spec:
  capacity: {storage: 1Gi}
  volumeMode: Filesystem
  accessModes: [ReadWriteOnce]
  persistentVolumeReclaimPolicy: Retain
  storageClassName: manual-local
  local: {path: /var/lib/k8s-course/m09}
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - {key: kubernetes.io/hostname, operator: In, values: [k8s-fundamentals-1]}
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata: {name: data, namespace: k8s-m09}
spec:
  accessModes: [ReadWriteOnce]
  storageClassName: manual-local
  resources: {requests: {storage: 512Mi}}
EOF
kubectl apply --dry-run=server -f /tmp/k8s-m09-storage.yaml
kubectl apply -f /tmp/k8s-m09-storage.yaml
kubectl get storageclass,pv
kubectl -n k8s-m09 get pvc data
kubectl -n k8s-m09 describe pvc data

cat > /tmp/k8s-m09-web.yaml <<'EOF'
apiVersion: apps/v1
kind: Deployment
metadata: {name: web, namespace: k8s-m09}
spec:
  replicas: 1
  selector: {matchLabels: {app: storage-web}}
  template:
    metadata: {labels: {app: storage-web}}
    spec:
      initContainers:
      - name: seed
        image: busybox:1.37
        command: ["sh", "-c", "test -f /data/index.html || printf 'created-by=%s\n' "$HOSTNAME" > /data/index.html"]
        volumeMounts: [{name: data, mountPath: /data}]
      containers:
      - name: nginx
        image: nginx:1.29-alpine
        ports: [{name: http, containerPort: 80}]
        volumeMounts: [{name: data, mountPath: /usr/share/nginx/html}]
      volumes:
      - name: data
        persistentVolumeClaim: {claimName: data}
EOF
kubectl apply --dry-run=server -f /tmp/k8s-m09-web.yaml
kubectl apply -f /tmp/k8s-m09-web.yaml
kubectl -n k8s-m09 rollout status deployment/web --timeout=180s
kubectl get pv k8s-m09-data
kubectl -n k8s-m09 get pvc data
pod=$(kubectl -n k8s-m09 get pod -l app=storage-web -o jsonpath='{.items[0].metadata.name}')
kubectl -n k8s-m09 exec "$pod" -- cat /usr/share/nginx/html/index.html
kubectl -n k8s-m09 delete pod "$pod" --wait=true
kubectl -n k8s-m09 rollout status deployment/web --timeout=180s
new_pod=$(kubectl -n k8s-m09 get pod -l app=storage-web -o jsonpath='{.items[0].metadata.name}')
kubectl -n k8s-m09 exec "$new_pod" -- cat /usr/share/nginx/html/index.html

cat > /tmp/k8s-m09-broken.yaml <<'EOF'
apiVersion: v1
kind: PersistentVolumeClaim
metadata: {name: impossible, namespace: k8s-m09}
spec:
  accessModes: [ReadWriteOnce]
  storageClassName: absent-provisioner
  resources: {requests: {storage: 20Gi}}
---
apiVersion: v1
kind: Pod
metadata: {name: broken-consumer, namespace: k8s-m09}
spec:
  containers:
  - {name: busybox, image: busybox:1.37, command: ["sh", "-c", "sleep 3600"]}
  volumes:
  - name: data
    persistentVolumeClaim: {claimName: claim-does-not-exist}
EOF
kubectl apply -f /tmp/k8s-m09-broken.yaml
kubectl -n k8s-m09 get pvc,pod
kubectl -n k8s-m09 describe pvc impossible
kubectl -n k8s-m09 describe pod broken-consumer
kubectl -n k8s-m09 get events --sort-by=.metadata.creationTimestamp
kubectl -n k8s-m09 delete pod broken-consumer
kubectl -n k8s-m09 delete pvc impossible

kubectl delete namespace k8s-m09 --wait=true
kubectl get pv k8s-m09-data
sudo cat /var/lib/k8s-course/m09/index.html
kubectl delete pv k8s-m09-data
kubectl delete storageclass manual-local
sudo rm -rf /var/lib/k8s-course/m09
rm -f /tmp/k8s-m09-*.yaml