Room9

CKAD - Application Deployment (RollingUpdate, Recreate) 본문

Kubernetes

CKAD - Application Deployment (RollingUpdate, Recreate)

Room9_ 2022. 1. 24. 17:02

배포전략

  • Blue/Green
  • Canary
  • RollingUpdate
  • Recreate

Recreate

기존의 버전을 모두 삭제하고 새로운 버전으로 배포

해당 배포 방법은 기존 버전을 모두 삭제하고 새로운 버전으로 업데이트 될때 사용자가 어플리케이션 서비스에 접근할 수 없어, 서비스 유지를 하지 못한다는 단점이 있다.

테스트 환경에서 사용가능 할 것이며, 또는 일정 시간에만 서비스하는 경우에 서비스 중단이 가능하다면 사용 할 수 있는 배포 방식이다.

Rolling Update

위의 Recreate 방식과 다르게 기존버전을 모두 삭제하는 것이 아닌, 이전 버전의 어플리케이션의 서비스를 내리고 새로운 버전의 어플리케이션을 올리는 방식이다. 이전버전을 내리고, 새로운 버전을 하나씩 올리는 방법이다. 쿠버네티스에서는 Rolling Update가 기본 배포 전략으로 동작 하게 된다.

KodeKloud

Q1.We have deployed a simple web application. Inspect the PODs and the Services

Wait for the application to fully deploy and view the application using the link called Webapp Portal above your terminal.

Q2. What is the current color of the web application? Access the Webapp Portal.

 > Blue

Q3.Run the script named curl-test.sh to send multiple requests to test the web application. Take a note of the output. Execute the script at /root/curl-test.sh.

Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK
Hello, Application Version: v1 ; Color: blue OK

Q4. Inspect the deployment and identify the number of PODs deployed by it

controlplane ~ ✦ ➜  k get deployments.apps 
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
frontend   4/4     4            4           6m14s

 > 4

Q5. What container image is used to deploy the applications?

controlplane ~ ✦ ➜  k describe deployments.apps frontend 
Name:                   frontend
Namespace:              default
CreationTimestamp:      Mon, 24 Jan 2022 07:38:09 +0000
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               name=webapp
Replicas:               4 desired | 4 updated | 4 total | 4 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        20
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  name=webapp
  Containers:
   simple-webapp:
    Image:        kodekloud/webapp-color:v1
    Port:         8080/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   frontend-7776cb7d57 (4/4 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  7m51s  deployment-controller  Scaled up replica set frontend-7776cb7d57 to 4

 > kodekloud/webapp-color:v1

Q6. Inspect the deployment and identify the current strategy

 > RollingUpdate

Q7. If you were to upgrade the application now what would happen?

 > PODs are upgraded few at a time

Q8. Let us try that. Upgrade the application by setting the image on the deployment to kodekloud/webapp-color:v2

Do not delete and re-create the deployment. Only set the new image name for the existing deployment.

controlplane ~ ✦ ➜  k set image deployment/frontend simple-webapp=kodekloud/webapp-color:v2
deployment.apps/frontend image updated
controlplane ~ ✦ ➜  k describe deployments.apps frontend 
Name:                   frontend
Namespace:              default
CreationTimestamp:      Mon, 24 Jan 2022 07:38:09 +0000
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 2
Selector:               name=webapp
Replicas:               4 desired | 2 updated | 5 total | 3 available | 2 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        20
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  name=webapp
  Containers:
   simple-webapp:
    Image:        kodekloud/webapp-color:v2
    Port:         8080/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  frontend-7776cb7d57 (3/3 replicas created)
NewReplicaSet:   frontend-7c7fcfc8cb (2/2 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  12m   deployment-controller  Scaled up replica set frontend-7776cb7d57 to 4
  Normal  ScalingReplicaSet  22s   deployment-controller  Scaled up replica set frontend-7c7fcfc8cb to 1
  Normal  ScalingReplicaSet  22s   deployment-controller  Scaled down replica set frontend-7776cb7d57 to 3
  Normal  ScalingReplicaSet  22s   deployment-controller  Scaled up replica set frontend-7c7fcfc8cb to 2

Q9. Run the script curl-test.sh again. Notice the requests now hit both the old and newer versions. However none of them fail. Execute the script at /root/curl-test.sh.

 > OK

Q10. Up to how many PODs can be down for upgrade at a time. Consider the current strategy settings and number of PODs - 4

 > 1 , rollingUpdateStrategy:  25% max unavailable, 25% max surge 이므로 4개의 25% 1개씩 롤링업데이트 된다.

Q11. Change the deployment strategy to Recreate.

Do not delete and re-create the deployment. Only update the strategy type for the existing deployment.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: frontend
  namespace: default
spec:
  replicas: 4
  selector:
    matchLabels:
      name: webapp
  strategy:
    Recreate:
    type: Recreate
  template:
    metadata:
      labels:
        name: webapp
    spec:
      containers:
      - image: kodekloud/webapp-color:v2
        name: simple-webapp
        ports:
        - containerPort: 8080
          protocol: TCP

Q12. Upgrade the application by setting the image on the deployment to kodekloud/webapp-color:v3

Do not delete and re-create the deployment. Only set the new image name for the existing deployment.

controlplane ~ ✦ ➜  k set image deployment/frontend simple-webapp=kodekloud/webapp-color:v3
deployment.apps/frontend image updated
controlplane ~ ✦ ➜  k get pods
NAME                        READY   STATUS        RESTARTS   AGE
frontend-7c7fcfc8cb-ggpbz   1/1     Terminating   0          2m18s
frontend-7c7fcfc8cb-4hl9d   1/1     Terminating   0          2m18s
frontend-7c7fcfc8cb-pp8ks   1/1     Terminating   0          2m19s
frontend-7c7fcfc8cb-fzrt9   1/1     Terminating   0          2m18s

controlplane ~ ✦ ➜  k get replicasets.apps -w
NAME                  DESIRED   CURRENT   READY   AGE
frontend-7c7fcfc8cb   0         0         0       2m40s
frontend-c68667579    4         4         0       5s
frontend-c68667579    4         4         1       7s
frontend-c68667579    4         4         2       8s
frontend-c68667579    4         4         3       8s
frontend-c68667579    4         4         4       8s

controlplane ~ ✦2 ✖ k get pods
NAME                       READY   STATUS    RESTARTS   AGE
frontend-c68667579-k4qr9   1/1     Running   0          20s
frontend-c68667579-2frmk   1/1     Running   0          20s
frontend-c68667579-rhvr8   1/1     Running   0          20s
frontend-c68667579-qnhmn   1/1     Running   0          20s

 

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