Automating Stateful Applications with Kubernetes Operators

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Automating Stateful Applications with Kubernetes Operators Jan Kleinert jan.kleinert@redhat.com September 23, 2019

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@jankleinert 2 Jan Kleinert Developer Advocate, Red Hat twitter/github: @jankleinert Hello!

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@jankleinert 3 What is Kubernetes? An open source orchestration system for managing containerized workloads across a cluster of nodes.

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@jankleinert 4 Pod Deployment DaemonSet ReplicaSet StatefulSet Job Kubernetes objects are persistent entities that represent the state of your cluster that you can manage with the K8s API EndPoints Ingress Service ConﬁgMap Secret StorageClass Namespace NetworkPolicy PersistentVolume Role RoleBinding ServiceAccount Understanding Kubernetes objects

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@jankleinert 5 Kubernetes Object Deﬁnitions kind: Pod apiVersion: v1 metadata: name: example-app spec: containers: - name: example image: quay.io/my/app:v1.2.0 [...]

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@jankleinert 6 Why should you care about operators?

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@jankleinert 7 Scaling stateless apps: easy

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@jankleinert 8 $ kubectl scale deploy/staticweb --replicas=3

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@jankleinert 9 scale up count=1 desired=3 ReplicaSet

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@jankleinert 10 start count=3 desired=3 ReplicaSet

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@jankleinert 11 What about apps that store data?

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@jankleinert 12 Creating a database is easy

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@jankleinert 13 $ kubectl run db --image=quay.io/my/db

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@jankleinert 14 Running a database over time is harder

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@jankleinert 15 ⏣ Resize/Upgrade ⏣ Reconﬁgure ⏣ Backup ⏣ Healing

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@jankleinert 16 Every application on any platform must be installed, conﬁgured, managed, and upgraded over time Patching is critical to security

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@jankleinert 17 Anything not automated is slowing you down

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@jankleinert 18 If only Kubernetes knew...

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@jankleinert 19

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@jankleinert 20

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@jankleinert 21 Operators are automated software managers that deal with installation and lifecycle of Kubernetes applications

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@jankleinert 22 1. Application-speciﬁc custom controllers 2. Custom resource deﬁnitions (CRD) Extending the Kubernetes API

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@jankleinert 23 The Operator Pattern K8S API CUSTOM RESOURCE & MY APP STATE WATCH EVENTS RECONCILE MY K8S APPLICATION Controller

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@jankleinert 24 Application-Speciﬁc Controllers

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@jankleinert 25 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 [...]

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@jankleinert 26 { }

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@jankleinert 27 What is etcd? Example: etcd Operator ● distributed key-value store ● primary datastore of Kubernetes ● stores and replicates all Kubernetes cluster state

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@jankleinert 28 Example: etcd Operator kind: EtcdCluster apiVersion: etcd.database.coreos.com/v1beta2 metadata: name: example-etcd-cluster spec: size: 3 version: "3.1.0"

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@jankleinert 29 Example: etcd Operator

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@jankleinert 31 https://learn.openshift.com/operatorframework/ Try It! Hands-On Operator Tutorials

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@jankleinert 32 Use Operators Today OperatorHub.io is a home for the Kubernetes community to share Operators. Find an existing Operator or list your own today.

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@jankleinert 33 https://github.com/operator-framework

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@jankleinert 37 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

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@jankleinert 38 https://github.com/operator-framework https://coreos.com/operators/ https://operatorhub.io https://coreos.com/blog/introducing-operator-framework https://learn.openshift.com/operatorframework/ Resources

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