How to manage stateful applications in Kubernetes

Managing stateless applications with Kubernetes is easy, but it becomes complex when information needs to persist in time, like for example for databases.
During this talk, I will go through the state of the Kubernetes storage ecosystem and make a demo to demonstrate how to manage persistent volume in Kubernetes.

Transcript

1. How to manage stateful applications in Kubernetes Devoxx France - 2018 1
2. Florian Woerner DevOps Engineer / Cloud Architect Onmyown @woernfl florian.woerner@onmyown.io 2
3. Agenda • Context • Volume provider • Volumes lifecycle management • Demo • Conclusion 3 @woernfl
4. Why should I choose Kubernetes over VMs? 4 @woernfl
5. Because Kubernetes is a distributed system management framework 5
6. Why would we need to manage data persistence? 6 @woernfl
7. Because, stateless architecture… it does not exist 7
8. Types of volumes 8
9. Types of Volumes - Kubernetes Internals • configMap • downwardAPI • emptyDir • gitRepo • hostPath • local • persistentVolumeClaim • projected • Secret • csi 9 @woernfl
10. Types of Volumes - Public Cloud 10 @woernfl • awsElasticBlockStore • azureDisk • azureFile • gcePersistentDisk
11. Types of Volumes - Non Cloud Dependant • cephfs • fc (fibre channel) • flocker • glusterfs • nfs • iscsi • portworxVolume • quobyte • rbd (Rados Block Device) • scaleIO • storageos • vsphereVolume 11 @woernfl
12. Any issues? 12 @woernfl
13. CSI to the rescue 13
14. What is CSI? • Container Storage Interface • Adopted by Kubernetes, Mesos and Cloud Foundry (for the moment) • Supported as beta in Kubernetes 1.10 (planed to fall in stable for 1.12) • Is a standardized way of exposing storage to a container 14 @woernfl
15. Why is it so important? • Common interface to multiple platforms (standardisation) • Allow storage provider to release out of tree 15 @woernfl
16. Real world scenario with Bob the dev and John the Sysadmin 16
17. Scenario: Persistent Volumes and Claims 17
18. Scenario: Persistent Volumes and Claims 18 @woernfl Kubernetes Node Storage (NFS, EBS, ...)
19. Scenario: Persistent Volumes and Claims 19 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume
20. Scenario: Persistent Volumes and Claims 20 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim
21. Scenario: Persistent Volumes and Claims 21 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim Pod
22. Scenario: Persistent Volumes and Claims 22 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim Pod
23. Scenario: Dynamic Provisioning 23
24. Scenario: Dynamic Provisioning 24 @woernfl Kubernetes Node Storage (NFS, EBS, ...)
25. Scenario: Dynamic Provisioning 25 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Storage Class - SDD Storage Class - HDD
26. Scenario: Dynamic Provisioning 26 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Claim Storage Class - SDD Storage Class - HDD
27. Scenario: Dynamic Provisioning 27 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim Storage Class - SDD Storage Class - HDD
28. Scenario: Dynamic Provisioning 28 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim Pod Storage Class - SDD Storage Class - HDD
29. Scenario: Dynamic Provisioning 29 @woernfl Kubernetes Node Storage (NFS, EBS, ...) Persistent Volume Persistent Volume Claim Pod Storage Class - SDD Storage Class - HDD
30. Demo 30
31. Conclusion 31
32. References 32 • Volumes Kubernetes Doc: https://kubernetes.io/docs/concepts/storage/volumes/ • Kubernetes Tasks: https://kubernetes.io/docs/tasks/ • Configure a Pod to Use a PersistentVolume for Storage: https://kubernetes.io/docs/tasks/configure-pod-container/configure-persistent-volume-storage/ • Run a Single-Instance Stateful Application: https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/ • Run a Replicated Stateful Application: https://kubernetes.io/docs/tasks/run-application/run-replicated-stateful-application/ • StatefulSets Kubernetes Doc: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/ @woernfl
33. Thank you! 33 Link to the repos: https://github.com/woernfl/k8s-stateful-demo