Lightning Lab - CKA

Persistent Volume Claims and MySQL Deployment

The following output shows the PVC bound to a PersistentVolume and the MySQL deployment starting up. This is a common CKA task that tests your ability to create storage resources and wire them into a deployment.

kubectl  get pvc
NAME          STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
alpha-claim   Bound    alpha-pv   1Gi        RWO            slow           4s
controlplane $ kubectl  get pods
NAME                           READY   STATUS              RESTARTS   AGE
alpha-mysql-74ffffd5df-k55wj   0/1     ContainerCreating   0          9s
controlplane $ watch kubectl  get pods
controlplane $
controlplane $
controlplane $
controlplane $
controlplane $
controlplane $ watch kubectl  get pods^C
controlplane $ cat 5.yaml
#apiVersion: v1
#kind: PersistentVolume
#metadata:
#  name: alpha-pv
#spec:
#  accessModes:
#  - ReadWriteOnce
#  capacity:
#    storage: 1Gi
#  hostPath:
#    path: /opt/pv-1
#    type: ""
#  persistentVolumeReclaimPolicy: Retain
#  storageClassName: slow
#  volumeMode: Filesystem

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: alpha-claim
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: slow
  volumeMode: Filesystem

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: alpha-mysql
  namespace: alpha
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: alpha-mysql
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: alpha-mysql
    spec:
      containers:
      - env:
        - name: MYSQL_ALLOW_EMPTY_PASSWORD
          value: "1"
        image: mysql:5.6
        imagePullPolicy: Always
        name: mysql
        ports:
        - containerPort: 3306
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /var/lib/mysql
          name: mysql-data
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
      volumes:
      - name: mysql-data
        persistentVolumeClaim:
          claimName: alpha-claim

Kubernetes Controlplane and Node Upgrade

These commands walk through upgrading a Kubernetes cluster from one version to another. You first upgrade kubeadm, then apply the upgrade on the controlplane, drain the node, upgrade kubelet and kubectl, and finally uncordon the node. The same process is repeated on worker nodes.

# Update K8s controlplane
apt update
apt-cache madison kubeadm
apt-get update && apt-get install -y kubeadm=1.19.0-00
kubeadm version
kubectl  get nodes
kubeadm upgrade apply v1.19.0
kubectl drain controlplane --ignore-daemonsets
kubectl  get pods -A -owide
apt-get update && apt-get install -y kubelet=1.19.0-00 kubectl=1.19.0-00
systemctl daemon-reload
systemctl restart kubelet
kubectl  get nodes
kubectl  uncordon  controlplane
kubectl  get nodes
kubectl  drain node01 --ignore-daemonsets

ssh node01
apt-get update && apt-get install -y kubeadm=1.19.0-00
kubeadm version
kubeadm upgrade node
apt-get update && apt-get install -y kubelet=1.19.0-00 kubectl=1.19.0-00
...

kubectl  create  deployment  nginx-deploy --image=nginx:1.16
kubectl  rollout history deployment nginx-deploy
kubectl  set image deployment  nginx-deploy *=nginx:1.17 --record
kubectl  rollout history deployment nginx-deploy
kubectl  config set-context --current --namespace alpha

export ETCDCTL_API=3
etcdctl snapshot save /opt/etcd-backup.db    --cacert /etc/kubernetes/pki/etcd/ca.crt --key /etc/kubernetes/pki/etcd/server.key  --cert /etc/kubernetes/pki/etcd/server.crt
ls /opt/etcd-backup.db
kubectl   run secret-1401 -n admin1401 --image=busybox  -o yaml --dry-run=client > 7.yaml
vim 7.yaml
kubectl  exec -it -n admin1401  secret-1401 -- sh

kubectl  get deploy -n admin2406 -o custom-columns=DEPLOYMENT:.metadata.name,CONTAINER_IMAGE:.spec.template.spec.containers[*].image,READY_REPLICAS:.spec.replicas,NAMESPACE:.metadata.namespace --sort-by=.metadata.name > /opt/admin2406_data

YAML Manifests Used in the Lab

Below are the YAML manifests referenced in the lab tasks, including a secret-mounting pod and PVC/PV definitions.

for i in $(ls *.yaml); do echo -e "$i\n\n"; cat $i; done
7.yaml


apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: secret-1401
  name: secret-1401
  namespace: admin1401
spec:
  containers:
  - command:
    - sleep
    - "4800"
    image: busybox
    name: secret-admin
    resources: {}
    volumeMounts:
    - name: secret-volume
      mountPath: /etc/secret-volume
      readOnly: true
  volumes:
  - name: secret-volume
    secret:
      secretName: dotfile-secret
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
pvc.yaml


apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: alpha-claim
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 1Gi
  volumeMode: Filesystem
pv.yaml


apiVersion: v1
kind: PersistentVolume
metadata:
  name: alpha-pv
spec:
  accessModes:
  - ReadWriteMany
  capacity:
    storage: 1Gi
  hostPath:
    path: /opt/pv-1
  persistentVolumeReclaimPolicy: Retain
  volumeMode: Filesystem