[CKA] Udemy 실습문제풀이 - Mock Test 1

 

[kubernetes] 쿠버네티스 관련 글 목차

 

ㅁ 들어가며

 Udemy, certified-kubernetes-administrator-with-practice-tests > Mock test 과정을 정리하였습니다.

실습 풀이가 git에 있음 - Solution

 

1. Deploy a pod named nginx-pod using the nginx:alpine image

# 샘플 yaml 생성
$ kubectl run nginx-pod --image=nginx:alpine --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx-pod
  name: nginx-pod
spec:
  containers:
  - image: nginx:alpine
    name: nginx-pod
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

# yaml 파일 저장
$ kubectl run nginx-pod --image=nginx:alpine --dry-run=client -o yaml > pod.yaml

# apply
$ kubectl apply -f pod.yaml 
pod/nginx-pod created

 

2. Deploy a messaging pod using the redis:alpine image with the labels set to tier=msg.

# help를 통한 lable 구문 참조
$ kubectl run --help
~~
  # Start a hazelcast pod and set labels "app=hazelcast" and "env=prod" in the container
  kubectl run hazelcast --image=hazelcast/hazelcast --labels="app=hazelcast,env=prod"
~~

$ lable 구문 작성
$ kubectl run messaging --image=redis:alpine --labels="tier=msg"
pod/messaging created

 

3. Create a namespace named apx-x9984574.

# create 구문 생성
$ k create namespace apx-x9984574
namespace/apx-x9984574 created

 

4. Get the list of nodes in JSON format and store it in a file at /opt/outputs/nodes-z3444kd9.json.

$ k get no -o json > /opt/outputs/nodes-z3444kd9.json

 

 

5. Create a service messaging-service to expose the messaging application within the cluster on port 6379

# pod 확인
$ k get pods

# service 확인
$ k get svc

# expose help 참조
$ kubectl expose --help
# Create a service for a replicated nginx, which serves on port 80 and connects to the containers on port 8000
kubectl expose rc nginx --port=80 --target-port=8000

 # expose 구문작성
 $ kubectl expose messaging --port 6379 --name messaging-service
 
 #적용확인
  - 서비스 확인
$ kubectl get svc
 
  - pod 연결확인
$ kubectl descride svc messaging-service
~~
Endpoints: 10.x.x.x:6379
~~

# 10.x.x.x:6379 IP 동일 체크
$ kubectl get pods -o wide

 

6. Create a deployment named hr-web-app using the image kodekloud/webapp-color with 2 replicas.

# kube docs 검색: pod replias > deployment 참조
# replicas 구문 획득(Declarative, 선언적 방식)
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:1.14.2
        ports:
        - containerPort: 80
        
# 구문 작성(Imperative, 명령적 방식)
$ kubectl create deployment hr-web-app --image=kudekloud/webapp-color --replicas=2

 

 

7. Create a static pod named static-busybox on the controlplane node that uses the busybox image and the command sleep 1000.

# kube doc 검색: command > Define a Command and Arguments for a Container

apiVersion: v1
kind: Pod
metadata:
  name: command-demo
  labels:
    purpose: demonstrate-command
spec:
  containers:
  - name: command-demo-container
    image: debian
    command: ["printenv"]
    args: ["HOSTNAME", "KUBERNETES_PORT"]
  restartPolicy: OnFailure

# doc > Run a command in a shell
command: ["/bin/sh"]
args: ["-c", "while true; do echo hello; sleep 10;done"]

# coomand.yaml 완성
apiVersion: v1
kind: Pod
metadata:
  name: static-busybox
spec:
  containers:
  - name: static-busybox
    image: busybox
    command: ["/bin/sh"]
    args: ["-c", "sleep 1000;"]
  restartPolicy: OnFailure
  
# apply
$ k apply -f command.yaml
pod/static-busybox created


########################
# dry-run으로 yaml 획득 방법
$ k run static-busybox --image=busybox --dry-run=client -o yaml --command -- sleep 1000 > static-busybox.yaml
$ cat static-busybox.yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: static-busybox
  name: static-busybox
spec:
  containers:
  - command:
    - sleep
    - "1000"
    image: busybox
    name: static-busybox
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

$ mv static-busybox.yaml /etc/kubernetes/manifests/
$ kubectl get pods

 

8. Create a POD in the finance namespace named temp-bus with the image redis:alpine.

# -n fi 탭키를 눌러 namespace 존재 확인가능
$ k get ns
NAME              STATUS   AGE
apx-x9984574      Active   30m
default           Active   89m
finance           Active   95s
kube-flannel      Active   89m
kube-node-lease   Active   89m
kube-public       Active   89m
kube-system       Active   89m

# run 구문작성
$ k run temp-bus --image=redis:alpine -n finance 
pod/temp-bus created

 

 

9. A new application orange is deployed. There is something wrong with it. Identify and fix the issue.

# pod log 확인
$ k logs orange 
Defaulted container "orange-container" out of: orange-container, init-myservice (init)
Error from server (BadRequest): container "orange-container" in pod "orange" is waiting to start: PodInitializing

# container log 확인
$ k logs orange init-myservice
sh: sleeeep: not found

# PodInitializing에 문제 파악
$ k get po -o yaml
~~
initContainers:
    - command:
      - sh
      - -c
      - sleeeep 2;
~~ 

# command 수정
$ k edit po orange 
error: pods "orange" is invalid
A copy of your changes has been stored to "/tmp/kubectl-edit-3112330393.yaml"
error: Edit cancelled, no valid changes were saved.

# 수정사항 강제 적용
$ k replace -f /tmp/kubectl-edit-3112330393.yaml --force
pod "orange" deleted
pod/orange replaced

 

 

10. Expose the hr-web-app as service hr-web-app-service application 
on port 30082 on the nodes on the cluster.

# expose 명령문 작성
$ k expose deploy hr-web-app --name=hr-web-app-service --type NodePort --port 8080
service/hr-web-app-service exposed

# svc 확인
$ k get svc


# NodePort port 변경 30082
$ k edit svc

 

 

11. Use JSON PATH query to retrieve the osImages of all the nodes 
and store it in a file /opt/outputs/nodes_os_x43kj56.txt.

# 명령문 참조 참기
# kube doc cheat
# Get ExternalIPs of all nodes
kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'


# 명령문 작성 및 실행 결과
$ kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}'
Ubuntu 20.04.2 LTS Ubuntu 20.04.2 LTS


# 결과파일 생성
$ kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}' > /opt/outputs/nodes_os_x43kj56.txt.

 

 

12. Create a Persistent Volume with the given specification.

# kube doc 검색: Persistent Volumes > 오른쪽 index에서 Persistent Volumes 클릭
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv0003
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: slow
  
# vi 편집
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-analytics
spec:
  capacity:
    storage: 100Mi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
  hostPath:
    path: /pv/data-analytics

 ㅇ 참조 doc

 - PersistentVolume

 - Create a PersistentVolume