[K8S] CKA - mock exam #1

0. setup env.

k8s 공식 문서 > kubectl cheat sheet에서 autocomplete 설정

# 시험 시작 전 초기 설정.
source <(kubectl completion bash) # bash-completion 패키지를 먼저 설치한 후, bash의 자동 완성을 현재 셸에 설정한다
echo "source <(kubectl completion bash)" >> ~/.bashrc # 자동 완성을 bash 셸에 영구적으로 추가한다

alias k=kubectl
complete -o default -F __start_kubectl k

1. deploy pod

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

k run nginx-pod --image=nginx:alpine
# 명령어 수행 후, 항상 검증하기!
k get pod
k describe pod nginx-pod

2. deploy pod with labels

eploy a messaging pod using the redis:alpine image with the labels set to tier=msg.
Pod Name: messaging
Image: redis:alpine
Labels: tier=msg

# labels 설정에 대해서 확인하려면,
k run --help

k run messaging --image=redis:alpine --labels="tier=msg"
k describe pod messaging | grep -i labels

3. create Namespace

Create a namespace named apx-x9984574.

k create ns apx-x9984574
k get ns

4. get list of nodes in JSON format

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

k get nodes -o json > /opt/outputs/nodes-z3444kd9.json
cat /opt/outputs/nodes-z3444kd9.json

5. create a service to expose app

message-service라는 서비스를 만들어서 messging app을 expose
Create a service messaging-service to expose the messaging application within the cluster on port 6379.
Use imperative commands.
Service: messaging-service
Port: 6379
Type: ClusterIp
Use the right labels

k expose --help

k expose pod messaging --port=6379 --name=messaging-service
k get svc
k describe svc messaging-service

# endpoint를 확인하자.
k get pods -o wide

# messaging pod의 IP와 동일한지 확인.

6. create a deployment

Create a deployment named hr-web-app using the image kodekloud/webapp-color with 2 replicas.
Name: hr-web-app
Image: kodekloud/webapp-color
Replicas: 2

k create deployment hr-web-app --image kodekloud/webapp-color --replicas 2
k get deployment
k describe deployment hr-web-app

7. create a static pod

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

# 1. yaml 파일을 직접 작성
# static pod를 실행할 노드를 선택한다.
ssh [노드 명]

# /etc/kubernetes/manifests 로 이동하여 해당 경로에 static pod의 yaml 파일 작성.
cd /etc/kubernetes/manifests
vi static-pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: static-busybox
spec:
  containers:
    - name: static-busybox
      image: busybox
      command: ["sleep","1000"]
      
 k apply -f static-pod.yaml
 
 # 2. dry-run을 통한 방법
 k run static-busybox --image busybox --dry-run=client -o yaml --command -- sleep 1000 > static-pod.yaml
 
 mv static-pod.yaml /etc/kubernetes/manifest
 
 # static pod 생성 확인
 k get pod
      

8. create pod in specific namespace

create a POD in the finance namespace named temp-bus with the image redis:alpine

k run temp-bus -n finance --image redis:alpine
k get pod -n finance

9. troubleshooting for POD

a new app orange is deployed. there is something wrong with it. Identify and fix the issue

k get pods

# Init:CrashLoopBackoff 상태 -> pod에 문제가 있다 / init 컨테이너에 문제가 있다
k describe pod orange

# init 컨테이너의 command에 문제가 있음
k edit pod orange
k replace --force -f /tmp~~~~.yaml
k get pod --watch

10. expose deployment

expose the hr-web-app as svc hr-web-app-service app on port 30082 on the nodes on the cluster
the web app listens on port 8080

# 현재 deployment 확인
k get deploy
k expose deploy hr-web-app --name hr-web-app-service --type NodePort --port 8080 

# 생성 후 확인
k get svc
k describe svc hr-web-app-service

# 두 개의 endpoints 있는 지 확인

# edit으로 nodePort 추가 spec.ports.nodePort: 30082

11. JSON path 파일 이용해 모든 노드의 os 이미지 저장

# kubectl cheet sheet에 jsonpath 참고
k get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}' > {파일경로}

12. create PV

create a persistent volume with the given specification
name: pv-analystics
storage: 100Mi
access mode: RWM
Host Path: /pv/data-analystics

# search persistent volume
# copy template

vi pv.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-analystics
spec:
  capacity:
    storage: 100Mi
  accessModes:
    - ReadWriteMany
  hostPath:
  	path: /pv/data-analystics
    
k create -f pv.yaml
k get pv
k describe pv pv-analytics