Automating Stateful Applications with Kubernetes Operators Josh Wood Developer Advocate Red Hat 

2 Why should you care about Operators? 

3 Any application in any system must be installed, configured, managed and upgraded over time Patching is critical to security 

“Anything that isn’t automated is slowing you down” 4 

5 What is Kubernetes? An open source orchestration system for managing containerized workloads across a cluster of nodes. 

6 Kubernetes Object Definitions kind: Pod apiVersion: v1 metadata: name: example-app spec: containers: - name: example image: quay.io/my/app:v1.2.0 [...] 

Kubernetes is a declarative platform 7 

8 Scaling stateless apps: easy 

9 $ kubectl scale deploy/staticweb --replicas=3 

10 scale up count=1 desired=3 ReplicaSet 

11 start count=3 desired=3 ReplicaSet 

12 What about apps that store data? 

13 Deploying a database is easy 

14 $ kubectl create deployment db --image=quay.io/my/db 

15 Running a database over time is harder 

16 ⏣ Resize/Upgrade ⏣ Reconfigure ⏣ Backup ⏣ Healing 

17 If only Kubernetes knew... 

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20 Operators are automated software managers that manage the entire lifecycle of Kubernetes applications 

21 1. Application-specific custom controllers 2. Custom resource definitions (CRD) Extending the Kubernetes API 

22 Custom Resource Developer / Kubernetes User Deployments StatefulSets Autoscalers Secrets Config maps PersistentVolume How Does an Operator Work? K8s API kind: ProductionReadyDatabase apiVersion: database .example.com/v1alpha1 metadata: name: my-important -database spec: connectionPoolSize: 300 readReplicas: 2 version: v4.0.1 Custom Kubernetes Controller Watch Events Reconciliation + Custom Resource Definition Kubernetes Operator Native Kubernetes Resources 

23 Custom Resource (CR) kind: ProductionReadyDatabase apiVersion: database.example.com/v1alpha1 metadata: name: my-production-ready-database spec: clusterSize: 3 readReplicas: 2 version: v4.0.1 [...] 

24 What is etcd? Example: etcd Operator ● distributed key-value store ● At the heart of Kubernetes ● Vault, many other apps ● Your apps... 

25 Example: etcd Operator kind: EtcdCluster apiVersion: etcd.database.coreos.com/v1beta2 metadata: name: example-etcd-cluster spec: size: 3 version: "3.2.13" 

26 Use Operators Today OperatorHub.io is a home for the Kubernetes community to share Operators. Find an existing Operator or list your own today. 

27 Operator Highlights MATURITY LEVEL 4 OPERATORS MATURITY LEVEL 5 OPERATORS 

28 https://github.com/operator-framework 

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OPERATOR SDK KUBERNETES OPERATOR + = AUTHOR “create new operator” scaffolding custom logic 

31 Operator Maturity Model Phase I Phase II Phase III Phase IV Phase V Basic Install Automated application provisioning and configuration management Seamless Upgrades Patch and minor version upgrades supported Full Lifecycle App lifecycle, storage lifecycle (backup, failure recovery) Deep Insights Metrics, alerts, log processing and workload analysis Auto Pilot Horizontal/vertical scaling, auto config tuning, abnormal detection, scheduling tuning 

32 https://learn.openshift.com/operatorframework/ Try It! Hands-On Operator Tutorials 

33 https://github.com/operator-framework https://operatorhub.io https://learn.openshift.com/operatorframework/ http://bit.ly/kubernetes-operators Resources 

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