Automating Stateful Applications Using Kubernetes Operators

Kubernetes scales and manages stateless applications quite easily. Stateful applications can require more work. They can be harder to dynamically manage with data intact and sometimes come with their own notion of clustering. Operators are Kubernetes agents that know how to deploy, scale, manage, back up, and even upgrade complex stateful applications. The Operator pattern was introduced by CoreOS. It has been adopted by many community projects, including Rook and Prometheus, and is supported by this spring’s release of the Operator Framework by Red Hat.

First, we offer an overview of Operators and lead a demonstration on installing and using an Operator on a OpenShift Kubernetes cluster. With an understanding of Operators in place, we then detail the Operator Framework and its main components, the Operator SDK and the lifecycle management backplane.

Transcript

1. Automating Stateful Applications with Kubernetes Operators Jan Kleinert jan.kleinert@redhat.com February 6, 2019
2. @jankleinert 2 Jan Kleinert Developer Advocate, Red Hat twitter/github: @jankleinert Hello!
3. @jankleinert 3 What is Kubernetes?
4. @jankleinert 4 Why should you care about operators?
5. @jankleinert 5 Scaling stateless apps: easy
6. @jankleinert 6 $ kubectl scale deploy/staticweb --replicas=3
7. @jankleinert 7 scale up count=1 desired=3 ReplicaSet
8. @jankleinert 8 start count=3 desired=3 ReplicaSet
9. @jankleinert 9 What about apps that store data?
10. @jankleinert 10 Creating a database is easy
11. @jankleinert 11 $ kubectl run db --image=quay.io/my/db
12. @jankleinert 12 Running a database over time is harder
13. @jankleinert 13 ⏣ Resize/Upgrade ⏣ Reconfigure ⏣ Backup ⏣ Healing
14. @jankleinert 14 Every application on any platform must be installed, configured, managed, and upgraded over time Patching is critical to security
15. @jankleinert 15 Anything not automated is slowing you down
16. @jankleinert 16 If only Kubernetes knew...
17. @jankleinert 17
18. @jankleinert 18
19. @jankleinert 19 Operators are automated software managers that deal with installation and lifecycle of Kubernetes applications
20. @jankleinert 20 1. Application-specific custom controllers 2. Custom resource definitions (CRD) Extending the Kubernetes API
21. @jankleinert 21 Application-Specific Controllers
22. @jankleinert 22 Custom Resource Definition (CRD) kind: ProductionReadyDatabase apiVersion: database.example.com/v1alpha1 metadata: name: my-production-ready-database spec: clusterSize: 3 readReplicas: 2 version: v4.0.1 [...]
23. @jankleinert 23 { }
24. @jankleinert 24 What is etcd? Example: etcd Operator • distributed key-value store • primary datastore of Kubernetes • stores and replicates all Kubernetes cluster state
25. @jankleinert 25 Example: etcd Operator kind: EtcdCluster apiVersion: etcd.database.coreos.com/v1beta2 metadata: name: example-etcd-cluster spec: size: 3 version: "3.1.0"
26. @jankleinert 26 Example: etcd Operator
27. @jankleinert 27
28. @jankleinert 28 https://learn.openshift.com/operatorframework/ (or come by the OpenShift booth #601) Try It! Hands-On Operator Tutorials
29. @jankleinert 29 https://github.com/operator-framework/awesome-operators • etcd • Prometheus • Elasticsearch • MySQL • “and many more!” Use Operators Today
30. @jankleinert 30 https://github.com/operator-framework
31. @jankleinert 31
32. @jankleinert 32
33. @jankleinert 33
34. @jankleinert 34 Operator SDK
35. @jankleinert 35 https://github.com/operator-framework https://coreos.com/operators/ https://github.com/operator-framework/awesome-operators https://coreos.com/blog/introducing-operator-framework https://learn.openshift.com/operatorframework/ Resources
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