CKA - Section 5: Application Lifecycle Management

Section 5: Application Lifecycle Management

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90. Application Lifecycle Management

91. file download

92. Rolling Upgrade ans Rollback

Rollout and Versioning

 

Rollout Command

> kubectl rollout status deployment [deployment name]

> kubectl rollout history []

 

kubectl apply

> kubectl apply -f deployment-definition.yml

파일 고치고 다시 배포

 

> kubectl set image deployment/myapp-deployment nginx=nginx:1.9.1

deployment "myapp-deployment" image is updated

 

Recreate

RollingUpdate

 

Upgrades

내부에 새로운 복제본 세트를 생성하고 동시에 컨테이너 배포를 시작함

롤링 업데이트 전략에 따라 이전 복제본 세트를 삭제함

> kubectl get replicasets

 

Rollback

배포를 통해 이전 개정으로 롤백하여 변경 사항을 취소하고 롤아웃을 실행하고 이전 버전으로 돌아감

> kubectl rollout undo [deployment/myapp-deployment]

 

Summarize Commands

> kubectl create -f deployment-definition.yml

> kubectl get deployments

> kubectl apply -f deployment-definition.yml

> kubectl set image [deployment/myapp-deployment] nginx=nginx:1.9.1

> kubectl rollout status [deployment/myapp-deployment]

> kubectl rollout history [deployment/myapp-deployment]

> kubectl rollout undo [deployment/myapp-deployment]

 

93. Practice Test - Rolling Updates and Rollbacks

Inspect the deployment and identify the current strategy

> kubectl describe deployment -> 'StrategyType'

> kubectl edit deployment [frontend] -> file edit

 

94. Solution - Rolling Updates and Rollbacks

95. Configure Applications

- Configuring Command and Arguments on applications

- Configuring Environment Variables

- Configuring Secrets

 

96. Commands

 

97. Commandds and Arguments

kubernetes POD에서 명령과 인수

docker run 명령에 추가되는 모든 것은 포드 정의의 "args" 속성으로 이동

> docker run --name ubuntu-sleeper ubuntu-sleeper

> docker run --name ubuntu-sleeper ubuntu-sleeper 10

 

pod-definition.yml

apiVersion: v1

kind: Pod

metadata:

  name: ubuntu-sleeper-pod

spec:

  containers:

    - name: ubuntu-sleeper

       image: ubuntu-sleeper

       command: ["sleep2.0"]

       args: ["10"]

 

> kubectl create -f pod-definition.yml

정의한 커맨드와 인자들은 파드가 생성되고 난 이후에는 변경될 수 없다.

참고: command 필드는 일부 컨테이너 런타임에서 entrypoint에 해당된다.

 

FROM Ubuntu

ENTRYPOINT ["sleep"]

CMD ["5"]

    

설명                                                     | 도커 필드 이름     |     쿠버네티스 필드 이름

컨테이너에서 실행되는 커맨드     | Entrypoint          | command

커맨드에 전달되는 인자들             | Cmd                      | arg

 

98. Practice Test - Commands and Arguments

> kubectl run pod webapp-green --image=[image_name] --dry-run=client -o yaml > webapp-color-green.yml

 

99. Solutions - Commands and Arguments (Optional)

 

100. 

kubernetes 환경 변수 설정 방법

env는 배열이고 key-value1) Plain Key Value2) ConfigMap3) Secrets

 

101. Configuring ConfigMaps in Applications구성 데이터로 작업하는 방법pod 정의 파일에서 환경 변수를 설정하는 방법

 

1) Create ConfigMaps

imperative

> kubectl create configmap app-config --from-literal=APP_COLOR=blue --from-literal=APP_Mod=prod

 

declarative

> kubectl create -f

 

config-map.yaml

apiVersion: v1

kind: ConfigMap

metadata:

    name: app-config

            data:   

                APP_COLOR: blue

               APP_MOD: prod

 

> kubectl get configmaps

 

2) Inject into Pod

(1) ENV

envFrom:

     - configMapRef: 

          name: app-config

 

(2) SINGLE ENV

env: 

  - name: APP_COLOR

       valueFrom: 

          configMapKeyRef:

                  name: app-config

                  key: APP_COLOR

 

(3) VOLUME

volumes:

- name: app-config

-volume

   configMap:

       name: app-config

 

102. Practice Test: Environment Variables

103. Solutions - Environment Variables> kubectl get [pod_name] -o yaml > [sample_pod].yaml

 

104. Configure Secrets in Applications

암호나 키와 같은 민감한 정보를 저장하는데 사용됨

config와 같이 인코딩 되거나 해시된 형식으로 저장된다는 점을 제외하면 configMap과 유사함

 

1) Create Secret

- Imperative

> kubectl create secret generic <secret-name> --from-literal=<key>=<value>

> kubectl crreate secret generic app-secret --from-literal=DB_Host=mysql

 

> kubectl create secret generic <secret-name> --from-file=<path-to-file>

 

- Declarative

> kubectl create -f

secret-data.yaml

apiVersion: v1

kind: Secret

metadata:

    name: app-secret

data:

    DB_Host: mysql

    DB_User: root

    DB_Password: paswrd

> kuebectl create -f secret-data.yaml

 

인코딩된 형식으로 데이터를 저장해야함 base64

 

View Secrets

> kubectl get secrets

> kubectl describe secrets

> kubectl get secret app-secret -o yaml

 

Decode Secrets

> echo -n 'bxlzcw=' | base64 --decode

 

2) Inject into Pod

 

(1) ENV

envFrom:

    - secretRef:

              name: app-secret

 

(2) SINGLE ENV

env:

  - name: DB_Password

    valueFrom:

       secretKeyRef:

          name: app-secret

          key: DB_Password

 

(3) VOLUME

volumes:

- name: app-secret-volume

  secret:

     secretName: app-secret

 

105. A note about Secrets!

106. Practice Test - Secrets

107. Solution - Secrets (Optional)

 

108. Scale Applications

109. Multi Container PODs

LOG Agent / WEB Server

- Create

spec:

    containers:

    - name: ==> array 단일 포드에서 여러 컨테이너를 허용하기 때문에 배열

 

110. Practice Test - Multi Container PODs

> kubectl -n elastic-stack exec -it app cat /log/app.log

 

apiVersion: v1
kind: Pod
metadata:
  name: app
  namespace: elastic-stack
  labels:
    name: app
spec:
  containers:
  - name: app
    image: kodekloud/event-simulator
    volumeMounts:
    - mountPath: /log
      name: log-volume

  - name: sidecar
    image: kodekloud/filebeat-configured
    volumeMounts:
    - mountPath: /var/log/event-simulator/
      name: log-volume

  volumes:
  - name: log-volume
    hostPath:
      # directory location on host
      path: /var/log/webapp
      # this field is optional
      type: DirectoryOrCreate

 

111. Solutioin - Multi Container PODs

한번 더 체크해서 보기

 

112. Multi-container PODs Design Patterns

CKA 에서는 필요없는 부분

 

113. InitContainers

114. Practice Test - InitContainers

115. Solution - InitContainers (Optional)

initContainers:

- name: init-myservice

image: busybox:1.28

command: ['sh', '-c', 'echo The app is running! && sleep 3600']

 

116. Self Healing Applications

CKA 필요없는 부분

 

117. If you like it, Share it!