[CKA] Practice Test - Env Variables

CKA (https://www.credly.com/org/the-linux-foundation/badge/cka-certified-kubernetes-administrator)

문제1

How many PODs exist on the system?

In the current(default) namespace

풀이

controlplane ~ ➜  k get po
NAME           READY   STATUS    RESTARTS   AGE
webapp-color   1/1     Running   0          2m48s

문제2

What is the environment variable name set on the container in the pod?

풀이

controlplane ~ ➜  k get po webapp-color -o jsonpath='{..env}'
[{"name":"APP_COLOR","value":"pink"}]

문제3

What is the value set on the environment variable APP_COLOR on the container in the pod?

풀이

controlplane ~ ➜  k get po webapp-color -o jsonpath='{..env}'
[{"name":"APP_COLOR","value":"pink"}]

문제4

View the web application UI by clicking on the Webapp Color Tab above your terminal.

This is located on the right side.

풀이

• UI만 확인 해주었음

문제5

Update the environment variable on the POD to display a green background.

Note: Delete and recreate the POD. Only make the necessary changes. Do not modify the name of the Pod.

Pod Name: webapp-color

Label Name: webapp-color

Env: APP_COLOR=green

풀이

• 기존에 만들어 놓은 파드를 yaml로 추출해서 지울거 지우고 env만 수정함

apiVersion: v1
kind: Pod
metadata:
  labels:
    name: webapp-color
  name: webapp-color
spec:
  containers:
  - env:
    - name: APP_COLOR
      value: green
    image: kodekloud/webapp-color
    imagePullPolicy: Always
    name: webapp-color

문제6

View the changes to the web application UI by clicking on the Webapp Color Tab above your terminal.

If you already have it open, simply refresh the browser.

풀이

• UI 화면이 초록색으로 변경됨

문제7

How many ConfigMaps exists in the default namespace?

풀이

controlplane ~ ➜  k get cm
NAME               DATA   AGE
kube-root-ca.crt   1      23m
db-config          3      10s

문제8

Identify the database host from the config map db-config.

풀이

controlplane ~ ➜  k get cm db-config -o yaml
apiVersion: v1
data:
  DB_HOST: SQL01.example.com
  DB_NAME: SQL01
  DB_PORT: "3306"
kind: ConfigMap
metadata:
  creationTimestamp: "2024-01-01T06:33:36Z"
  name: db-config
  namespace: default
  resourceVersion: "1062"
  uid: a8f4fa92-a32d-4de2-a808-1cbcb7ed6af1

문제9

Create a new ConfigMap for the webapp-color POD. Use the spec given below.

ConfigMap Name: webapp-config-map

Data: APP_COLOR=darkblue

Data: APP_OTHER=disregard

풀이

controlplane ~ ➜  k create configmap webapp-config-map --from-literal=APP_COLOR=darkblue --from-literal=APP_OTHER=disregard
configmap/webapp-config-map created

문제10

Update the environment variable on the POD to use only the APP_COLOR key from the newly created ConfigMap.

Pod Name: webapp-color

ConfigMap Name: webapp-config-map

풀이

apiVersion: v1
kind: Pod
metadata:
  labels:
    name: webapp-color
  name: webapp-color
spec:
  containers:
  - env:
    - name: APP_COLOR
      valueFrom:
        configMapKeyRef:
          name: webapp-config-map
          key: APP_COLOR
    image: kodekloud/webapp-color
    imagePullPolicy: Always
    name: webapp-color

• 아까 생성했던 pod yaml 파일에서 configMapKeyRef를 이용해 key 기반으로 변수를 가져올수 있도록 해줌
• 대소문자 및 depth에 유의해야 할듯