CKA 정리 및 북마크

- context 매번 변경 확인

kubectl config use-context k8s

 

- etcd 위치 및 host Path 수정하여 적용 

/etc/kubernetes/manifests/etcd.yaml

...
 - hostPath:
      path: /var/lib/etcd-new
      type: DirectoryOrCreate
   name: etcd-data
...

 

- static POD 폴더의 위치 확인 yaml 파일 및 /etc/kubernetes/manifests 에 존재

/var/lib/kubelet/config.yaml

 

- dry-run=client 및 -o yaml

$ kubectl get pods eshop-cart-app -o yaml > eshop.yaml
$ kubectl run lab004 --image=nginx --dry-run=client -o yaml > multi.yaml

 

- scale 명령

 

- rolling update 명령

kubectl set image deployment nginx-app nginx=nginx:1.11.13-alpine --record
kubectl rollout history deployment nginx-app  # 내역 확인
kubectl rollout undo deployment nginx-app  # Rollback 하기

 

- 라벨 확인 

$ kubectl get nodes -L disktype

apiVersion: v1
kind: Pod
metadata:
  name: eshop-store
spec:
  containers:
  - image: nginx
    name: eshop-store
  nodeSelector:    # 노드 실렉터
    disktype: ssd

 

- cordon, drain 등

$ kubectl cordon [노드 명]
$ kubectl uncordon [노드 명]
$ kubectl drain [노드 명]
$ kubectl drain [노드 명] --ignore-daemonsets  # 데몬셋 무시

# 예시
$ kubectl drain node1.example.com --ignore-daemonsets --force --delete-emptydir-data

 

 

- node 개수 확인

$ kubectl get nodes | grep -i -w ready | wc -l > ./NODE-count
$ kubectl describe  nodes | grep -i taints   # taints가 있는 노드는 못 쓰니깐 제외

 

- expose my app

apiVersion: apps/v1 kind: Deployment metadata:   labels:     app: front-end   name: front-end spec:   replicas: 2   revisionHistoryLimit: 10   selector:     matchLabels:       app: front-end   template:     metadata:       labels:         app: front-end     spec:       containers:       - image: ghcr.io/shclub/nginx         name: http         ports:         - name: http           containerPort: 80 --- apiVersion: v1 kind: Service metadata:   labels:     app: front-end   name: front-end-svc spec:   ports:   - port: 80     protocol: TCP     targetPort: http     name: http   selector:     app: front-end   type: NodePort

 

- pod log  &  cpu 사용냥

# pod log
$ kubectl logs custom-app | grep 'file not found' >  ./podlog

# cpu 사용량
$ kubectl top po -l name=overloaded-cpu --sort-by=cpu

 

-  init 컨테이너

$ sudo vi /data/workdir/webpod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: web-pod
spec:
  containers:
  - image: busybox:1.28
    name: main
    command: ['sh','-c','if [ !-f /workdir/data.txt ];then exit 1;else sleep 300;fi']
    volumeMounts:
    - name: workdir
      mountPath: "/workdir"
  initContainers:
  - name: init
    image: busybox:1.28
    command: ['sh', '-c', "touch /workdir/data.txt"]
    volumeMounts:
    - name: workdir
      mountPath: "/workdir"
  volumes:
  - name: workdir
    emptyDir: {}

 

- config map 운영

$ kubectl create configmap web-config --from-literal=connection_string=localhost:80 --from-literal=external_url=cncf.io

apiVersion: v1 kind: Pod metadata:   labels:     run: web-pod   name: web-pod spec:   containers:   - image: nginx:1.19.8-alpine     name: web-pod     envFrom:     - configMapRef:         name: web-config     ports:     - containerPort: 80

---

쿠버네티스 홈 - https://kubernetes.io/ko/docs/home/

쿠버네티스 kubectl 명령 가이드라인 - https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands 

etcd - https://kubernetes.io/docs/tasks/administer-cluster/configure-upgrade-etcd/

sidr car or logging - https://kubernetes.io/docs/concepts/cluster-administration/logging/#sidecar-container-with-logging-agent

scale - https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#scale

rolling update - https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment

init container - https://kubernetes.io/docs/concepts/workloads/pods/init-containers/

node port - https://kubernetes.io/docs/concepts/services-networking/service/#nodeport

 

config map - https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#create-a-configmap

config map pod - https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#define-container-environment-variables-using-configmap-data

secret - https://kubernetes.io/docs/concepts/configuration/secret/#use-cases

secret file - https://kubernetes.io/docs/concepts/configuration/secret/#using-secrets-as-files-from-a-pod

secret env - https://kubernetes.io/docs/concepts/configuration/secret/#using-secrets-as-environment-variables

hostpath - https://kubernetes.io/docs/concepts/storage/volumes/#hostpath

persistant volume - https://kubernetes.io/docs/concepts/storage/persistent-volumes/#persistent-volumes

persistant volume claim - https://kubernetes.io/ko/docs/concepts/storage/persistent-volumes/#%ED%8D%BC%EC%8B%9C%EC%8A%A4%ED%84%B4%ED%8A%B8%EB%B3%BC%EB%A5%A8%ED%81%B4%EB%A0%88%EC%9E%84

persistant volume claim woth pod -  https://kubernetes.io/ko/docs/concepts/storage/persistent-volumes/#%EB%B3%BC%EB%A5%A8%EC%9C%BC%EB%A1%9C-%ED%81%B4%EB%A0%88%EC%9E%84%ED%95%98%EA%B8%B0

쿠버 업그레이드 - https://v1-21.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/