透過K8S的API來設計工具或應用程式 (Java) 使用官方版本的Kubernetes客戶端框架創建一個構建簡單但功能強大的工具範例: PVCWatch 本文件將聚焦在介紹如何使用Java程式語言的客戶端。 為了說明這些客戶端框架的用法，我們將創建一個簡單的CLI工具 這個工具PVCWatch會監視與計算K8S群集中PVC (Persistent Volume Claim)的使用總量, 並檢查它是否達到指定閥值 當總量達到閥值時，它會採取一個動作（在這個例子中，會在console上打印出一個簡單的通知） Youtube: https://youtu.be/EJr_NWzZdKc Github: https://github.com/erhwenkuo/k8s-client-java-examples

1. Cloud Native: Building stuff with the Kubernetes API
K8S API
(Java)
1

2. Agenda
1. Introduction The Kubernetes Clients
2. A simple client tool for Kubernetes
3. The Kubernetes Java Client
• Connecting to the API server
• Listing cluster PVCs
• Watching the cluster PVCs
4. Run the program
5. Summary
2

3. • 5 /
• 3 MES/SFC
• 3 ERP (SAP-MM )/EAI Leader
• 2 End-To-End Business Integration Analyst
• 1 OEM Sales Team Leader
• 4 /
• 6 /
• IT –
• 4.0 / -
erhwenkuo@gmail.com
3

4. K8S API
4

5. • Kubernetes
: PVCWatch
• JavaI

6. • Kubernetes
• Go client
• OpenAPI clients

7. • Go client C K
• K8S
• Kubernetes

8. • Kubernetes
• Swagger (OpenAPI) C
• https://github.com/kubernetes-client/gen

9. • C Kubernetes Java Python
JavaScript typescript
• Java

10. K8S
10

11. • l K c A e CLI
• l PVCWatch i K8S PVC (Persistent Volume
Claim) fo, n p
• fon p l
console e mb

12. • AKubernetes :
• (connectivity)
• (resource list retrieval and walk through)
• K (object watch)
• A

13. • f Kubernetes b
eAPI
• K c A Kubernetes

14. Kubernetes
Java
14

15. • Kubernetes Java Java Swagger
• https://github.com/kubernetes-client/java

16. API
(connectivity)
16

17. • Java I C A API
• Config.defaultClient ApiClient

18. • Config ApiClient utility
I K8S APIP A
• Within a cluster
• From a config file
• Auto-detect
• I C

19. • P Kubernetes C
A ApiClientI

20. • A kubeconfig I
C ApiClient

21. • defaultClient n c h
eP I g :
1. C o $KUBECONFIG kubeconfig ,
$HOME/.kube/config
2. (1) c s ( r
i )
3. (1) (2)v c n c http://
localhost:8080 t K8S API A

22. • ApiClientC eK8S API j b i
• P l A c e
b I API
• Java aOpenAPI b
API b

23. • CoreV1Api Kubernetes V1
APIA C:

24. PVCs
(resource list retrieval and
walk through)
24

25. • API VL API
• C listNamespacedPersistentVolumeClaim()
P PVC
• P V1PersistentVolumeClaimList

27. • printPVCs PersistentVolumeClaims

28. PVC
(object watch)
28

29. • Javat h K8S WAPI P
c i C na ADDED MODIFIED DELETED
• CLI K8S PVC
(Persistent Volume Claim) , usV eW
• WP l r 2Gi n
• console
• r g

30. • Watch Watch.createWatch
API V1PersistentVolumeClaim

31. • SsetReadTimeout() ”0”( HTTP
K8S API c a )
•

32. • createWatch
API
• Quantity L

33. Watch K8S
,
channel ,
, Watch

34. • v V sn switcht K8S API e
• ADDED o PVC
• MODIFIED o PVC
• DELETED o PVC C
• i g PVC r c
totalClaims
• P c maxClaims console

37. • PVC C
P PVC

38. 38

39. • PVC
PersistentVolumeClaim

40. • ( Helm) K8S
100Gi (persistent storage claim)

41. • R pvcwatch PVC
PVC

42. • K8S PVC
redis 100Gi PVC
PVCWatch

43. 43

44. • Kubernetes
API
• https://www.slideshare.net/erhwenkuo/cncf-explore-k8sapi
• a Kubernetes Java
CLI S (namespace) PVC
• Kubernetes Java K8S API
a

45. - 7 A: 99 I 8 0 58 A8 8 2. 2 K A: /
• 87 B B: A: 58 A8 8 5 7 A:
99 I 8 58 A8 8 A:
85) 99(
199 / 8A 5 J 9B 58 A8 8
• : 5 B 58 A8 8 8A

46. 46