Let’s dive into Kubernetes operator creation

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Let’s dive into Kubernetes operator creation Horacio Gonzalez 2023-11-09

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Who are we? Introducing myself and introducing OVHcloud

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Horacio Gonzalez @LostInBrittany Spaniard Lost in Brittany

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OVHcloud PRIVATE CLOUD 33 Data Centers in 13 locations 1 Million+ Servers produced since 1999 PUBLIC CLOUD 44 Points of Presence on a 36 TBPS Bandwidth Network 1.6 Million Customers across 140 countries 2800+ Employees worldwide 308 Million euros adjusted EBITDA (2022) WEB CLOUD 117K+ Private Cloud VM running P.U.E. 1,10 – 1,30 Energy efficiency indicator PAAS 340K Public Cloud Instances running Over 20 Years in Business Disrupting since 1999 BARE METAL 400K Physical Servers in our data centers

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Warning Gophers, gophers everywhere!

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Last year in DevOps Barcelona

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We proposed a sequel for this year Let’s dive into Kubernetes operator creation

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But at the end Aurélie couldn’t come So I must do it alone… Wish me luck!

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And why Gophers? Because we love Gophers, of course! And because Golang and Kubernetes are so linked…

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Credit where it is due All the gophers you will see are drawn by Aurélie and Horacio, and are based on the Go mascot designed by Renee French which is licensed under CC BY 3.0.

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Kubernetes operators Helping to tame the complexity of K8s Ops

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Taming microservices with Kubernetes

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What about complex deployments

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Tools like Helm helps with complexity

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Helm Charts are configuration Operating is more than installs & upgrades

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Kubernetes is about automation How about automating human operators?

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Kubernetes Operators A Kubernetes version of the human operator

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Building operators Basic K8s elements: Controllers and Custom Resources

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Kubernetes Controllers Keeping an eye on the resources

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A reconcile loop Controllers watch the state of the cluster, and make or request changes where needed

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Custom Resource Definitions Extending Kubernetes API

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Extending Kubernetes API By defining new types of resources, internal or external to the cluster

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With a CRD you can create CR in the cluster They are the blueprints of the Custom Resources

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Custom Resources are simply data All the logic must be in the Controller

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Kubernetes Operator Automating operations

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What’s a Kubernetes Operator?

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Example: databases Things like adding an instance to a pool, doing a backup, sharding…

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Knowledge encoded in CRDs and Controllers

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Custom Controllers for Custom Resources Operators implement and manage Custom Resources using custom reconciliation logic

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Operator Capability Model Gauging the operator maturity

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How can we write Operators? Which language? Any framework?

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They are simply pods and manifests You can simply call Kubernetes APIs or use a compatible client

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How to write an Operator

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The Operator Framework Open source framework to accelerate the development of an Operator

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Operator SDK

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Our objective Why? Because we can!

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What do we want? ● In a simple and easy Kubernetes operator ● Handle cute Gophers ● In Javascript, because it’s very expressive and easy to understand… and I like it 😁

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All the code is available https://github.com/LostInBrittany/lets-dive-into-kubernetes-operator-creation

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Aurélie’s Gopher repository https://github.com/scraly/gophers

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random-gopher container https://hub.docker.com/r/lostinbrittany/random-gopher

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random-gopher container import express from ‘express’; import { readdir } from ‘node:fs/promises’; import path from ‘node:path’; let app = express(); let chosenGopher; async function initFiles() { try { const files = await readdir(‘gophers’); const gophers = files.filter( (item) => item.endsWith(‘png’) || item.endsWith(‘jpg’) ); const randomIndex = Math.floor((Math.random()*gophers.length)); chosenGopher = gophers[randomIndex]; console.log(chosenGopher); } catch (err) { console.error(err); } } At startup it chooses and exposes a random gopher

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random-gopher-deployment apiVersion: apps/v1 kind: Deployment metadata: name: random-gopher spec: selector: matchLabels: run: random-gopher replicas: 10 template: metadata: labels: run: random-gopher spec: containers: - name: random-gopher image: lostinbrittany/random-gopher:0.0.4 ports: - containerPort: 8080 Deploying lots of random-gophers in the cluster

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Applying it to the cluster Deploying random-gopher-deployment Deploying the manifest kubectl apply -f manifests random-gopher-deployment.yaml Getting pods’ address kubectl get pods -o wide Create a busybox kubectl run -i —tty —rm debug —image=busybox —restart=Never — sh Asking for a Gopher name wget -qO - [pod_ip]:8080/gopher/name Let’s switch to the terminal…