[따배씨] 14. Init container를 포함한 pod 운영 / CKA 시험 문제 학습

이 포스팅은 아래의 유튜브 채널 "따배"를 따라서 학습한 내용입니다.  

 

 

[관련 이론]

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[Precondition]

(1) 테스트 환경

(1.1) Rocky Linux Cluster 

: 직접 구성

[root@k8s-master ~]# k get nodes -o wide
NAME         STATUS   ROLES           AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                            KERNEL-VERSION                  CONTAINER-RUNTIME
k8s-master   Ready    control-plane   30d   v1.27.2   192.168.56.30   <none>        Rocky Linux 8.10 (Green Obsidian)   4.18.0-553.33.1.el8_10.x86_64   containerd://1.6.32
k8s-node1    Ready    <none>          30d   v1.27.2   192.168.56.31   <none>        Rocky Linux 8.8 (Green Obsidian)    4.18.0-477.10.1.el8_8.x86_64    containerd://1.6.21
k8s-node2    Ready    <none>          30d   v1.27.2   192.168.56.32   <none>        Rocky Linux 8.8 (Green Obsidian)    4.18.0-477.10.1.el8_8.x86_64    containerd://1.6.21
[root@k8s-master ~]#

 

(1.2) Ubuntu Cluster 

: kodekloud 테스트 환경 활용

controlplane ~ ➜  kubectl get nodes -o wide
NAME           STATUS   ROLES           AGE     VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION   CONTAINER-RUNTIME
controlplane   Ready    control-plane   9m6s    v1.31.0   192.6.94.6    <none>        Ubuntu 22.04.4 LTS   5.4.0-1106-gcp   containerd://1.6.26
node01         Ready    <none>          8m31s   v1.31.0   192.6.94.9    <none>        Ubuntu 22.04.4 LTS   5.4.0-1106-gcp   containerd://1.6.26

https://learn.kodekloud.com/user/courses/udemy-labs-certified-kubernetes-administrator-with-practice-tests

 

 

(2) 사전 필요 설정 

- 문제에서 제시하는 web-pod 생성해두기

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"
  volumes:
  - name: workdir
    emptyDir: {}

---

 

 

[Question]

Perform the following

Tasks:
Add an init container to web-pod(which has been defined in spec file /data/cka/webpod.yaml).
The init container should create an empty file named /workdir/data.txt.
If /workdir/data.txt is not detected the Pod should exit.
Once the spec file has been updated with the init container definition, the Pod should be created.

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[Solve]

(1) webpod.yaml 수정 

[root@k8s-master ~]# cat data/cka/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"
  volumes:
  - name: workdir
    emptyDir: {}
[root@k8s-master ~]# 
[root@k8s-master ~]# vi data/cka/webpod.yaml

 

 

(2) 수정한 pod 확인 

[root@k8s-master ~]# k get pods 
NAME                       READY   STATUS    RESTARTS   AGE
cpuload-669c759d97-2f269   1/1     Running   0          38m
cpuload-669c759d97-5qdkw   1/1     Running   0          38m
cpuload-669c759d97-7dq4w   1/1     Running   0          38m
cpuload-669c759d97-kxrhj   1/1     Running   0          38m
cpuload-669c759d97-qhgl2   1/1     Running   0          38m
web-pod                    1/1     Running   0          48s
[root@k8s-master ~]# 
[root@k8s-master ~]# k exec -it web-pod -c main -- ls -al /workdir/data.txt
-rw-r--r--    1 root     root             0 Jan 31 07:35 /workdir/data.txt

 

 

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[사용 커맨드 정리]

- 생략