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CKAD) Blue-Green Update

Last updated at 2023-08-29Posted at 2023-08-29

概要

旧バージョン、新バージョンが両方動作し、トラフィックだけ新バージョンで転換

長所短所

長所

アップデートするのに、時間がかからない
リソースがすでに公開している途中で、トラフィックだけ修正するとアップデートが終わるので
ロールバックする時間が短い
旧バージョンもすでに動いている途中でトラフィックだけ修正するので

短所

パソコンのリソースをが普段よりかかる
旧バージョン、新バージョン両方動くので
ダウンタイム発生
短い時間かもしれないが、トラフィックを変わる時間でダウンタイムが発生

例

次のようなDeployments、Serviceを動作しなさい

Blueという名前でsmlinux/nginx:blueイメージを持つPodを2個デプロイしなさい
- Labelはversion=blueを利用し、ポート番号は8080
app-svcサービスをversion=blueラベルで集め、 NodePortタイプのサービス、ポート番号は80で運用しなさい
Greenという名前でsmlinux/nginx:greenイメージを持つPodを2個デプロイしなさい
- Labelはversion=blueを利用し、ポート番号は8080
app-svcサービスのラベルをversion=greenで変更しなさい

kubectl create deployment blue --image=smlinux/nginx:blue --port=8080 --replicas=2 --dry-run=client -o yaml > deployments.yaml

(修正前)deployments.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: blue
  name: blue
spec:
  replicas: 2
  selector:
    matchLabels:
      app: blue
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: blue
    spec:
      containers:
      - image: smlinux/nginx:blue
        name: nginx
        ports:
        - containerPort: 8080
        resources: {}
status: {}

(修正後)deployments.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    version: blue
  name: blue
spec:
  replicas: 2
  selector:
    matchLabels:
      version: blue
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        version: blue
    spec:
      containers:
      - image: smlinux/nginx:blue
        name: nginx
        ports:
        - containerPort: 8080
        resources: {}
---
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    version: green
  name: green
spec:
  replicas: 2
  selector:
    matchLabels:
      version: green
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        version: green
    spec:
      containers:
      - image: smlinux/nginx:green
        name: nginx
        ports:
        - containerPort: 8080
        resources: {}
---
apiVersion: v1
kind: Service
metadata:
  name: app-svc
spec:
  type: NodePort
  selector:
    version: blue
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080

:wq!

kubectl apply -f ./deployments.yaml

準備結果

controlplane $ kubectl get svc   
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
app-svc      NodePort    10.97.110.208   <none>        80:31380/TCP   2m8s
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        21d
controlplane $ kubectl get deployments
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
blue    2/2     2            2           2m15s
green   2/2     2            2           58s
controlplane $ kubectl get pods 
NAME                     READY   STATUS    RESTARTS   AGE
blue-5f6556c4d-p6l69     1/1     Running   0          2m12s
blue-5f6556c4d-zcr22     1/1     Running   0          2m11s
green-56c68bfddb-85kth   1/1     Running   0          60s
green-56c68bfddb-bpwwp   1/1     Running   0          60s
controlplane $ kubectl get nodes
NAME           STATUS   ROLES           AGE   VERSION
controlplane   Ready    control-plane   21d   v1.27.1
node01         Ready    <none>          21d   v1.27.1
controlplane $ curl node01:32684
BLUE app service: nginx_1.14

解決

edit コマンドを叩く

kubectl edit svc app-svc

(修正前)edit svc app-svc.yaml

  # Please edit the object below. Lines beginning with a '#' will be ignored,
 # and an empty file will abort the edit. If an error occurs while saving this file will be
 # reopened with the relevant failures.
 #
 apiVersion: v1
 kind: Service
 metadata:
   annotations:
     kubectl.kubernetes.io/last-applied-configuration: |
       {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"app-svc","namespace":"default"},"spec":{"ports":[{"port":80,"protocol":"TCP","targetPort":8080}],"selector":{"version":"blue"},"type":"NodePort"}}
   creationTimestamp: "2023-08-29T15:36:39Z"
   name: app-svc
   namespace: default
   resourceVersion: "3557"
   uid: cfa13548-483f-4c8d-bca4-756d2108c66d
 spec:
   clusterIP: 10.104.250.28
   clusterIPs:
   - 10.104.250.28
   externalTrafficPolicy: Cluster
   internalTrafficPolicy: Cluster
   ipFamilies:
   - IPv4
   ipFamilyPolicy: SingleStack
   ports:
   - nodePort: 32684
     port: 80
     protocol: TCP
     targetPort: 8080
   selector:
     version: blue
   sessionAffinity: None
   type: NodePort
 status:
   loadBalancer: {}

修正を行う

(修正後)edit svc app-svc.yaml

  # Please edit the object below. Lines beginning with a '#' will be ignored,
 # and an empty file will abort the edit. If an error occurs while saving this file will be
 # reopened with the relevant failures.
 #
 apiVersion: v1
 kind: Service
 metadata:
   annotations:
     kubectl.kubernetes.io/last-applied-configuration: |
       {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"app-svc","namespace":"default"},"spec":{"ports":[{"port":80,"protocol":"TCP","targetPort":8080}],"selector":{"version":"blue"},"type":"NodePort"}}
   creationTimestamp: "2023-08-29T15:36:39Z"
   name: app-svc
   namespace: default
   resourceVersion: "3557"
   uid: cfa13548-483f-4c8d-bca4-756d2108c66d
 spec:
   clusterIP: 10.104.250.28
   clusterIPs:
   - 10.104.250.28
   externalTrafficPolicy: Cluster
   internalTrafficPolicy: Cluster
   ipFamilies:
   - IPv4
   ipFamilyPolicy: SingleStack
   ports:
   - nodePort: 32684
     port: 80
     protocol: TCP
     targetPort: 8080
   selector:
     version: green # 修正箇所
   sessionAffinity: None
   type: NodePort
 status:
   loadBalancer: {}

保存する
```
:wq!
```

結果確認

controlplane $ curl node01:32684
BLUE app service: nginx_1.14 
controlplane $ kubectl edit service app-svc
service/app-svc edited
controlplane $ curl node01:32684
GREEN app service: nginx_1.15

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