A presentation at Config Management Camp in in Ghent, Belgium by Horacio Gonzalez
Let’s dive into Kubernetes operator creation Horacio Gonzalez 2024-04-06
Who are we? Introducing myself and introducing Clever Cloud
Horacio Gonzalez @LostInBrittany Spaniard Lost in Brittany
Clever Cloud Our mission: give more speed to your teams and better quality to your projects
Warning Gophers, gophers everywhere!
Last year in Config Management Camp
I proposed a sequel for this year Let’s dive into Kubernetes operator creation This time Aurélie can’t do the talk with me 😢 So I must do it alone… Wish me luck!
And why Gophers? Because we love Gophers, of course! And because Golang and Kubernetes are so linked…
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.
Kubernetes operators Helping to tame the complexity of K8s Ops
Taming microservices with Kubernetes
What about complex deployments
Tools like Helm helps with complexity
Helm Charts are configuration Operating is more than installs & upgrades
Kubernetes is about automation How about automating human operators?
Kubernetes Operators A Kubernetes version of the human operator
Building operators Basic K8s elements: Custom Resources & Controllers
Custom Resource Definitions Extending Kubernetes API
Extending Kubernetes API By defining new types of resources, internal or external to the cluster
With a CRD you can create CR in the cluster They are the blueprints of the Custom Resources
Custom Resources are simply data All the logic must be in the Controller
Kubernetes Controllers Keeping an eye on the resources
A reconcile loop Controllers watch the state of the cluster, and make or request changes where needed
Kubernetes Operator Automating operations
What’s a Kubernetes Operator?
Example: databases Things like adding an instance to a pool, doing a backup, sharding…
Knowledge encoded in CRDs and Controllers
Custom Controllers for Custom Resources Operators implement and manage Custom Resources using custom reconciliation logic
Operator Capability Model Gauging the operator maturity
A real, open-source example The Clever Operator
Available on Operator Hub & GitHub https://operatorhub.io/operator/clever-operator https://github.com/CleverCloud/clever-operator
Exposing Clever Cloud resources as CRD Allowing your apps to use our DBs as if they were in K8s
How can we write Operators? Which language? Any framework?
They are simply pods and manifests You can simply call Kubernetes APIs or use a compatible client
How to write an Operator
The Operator Framework Open source framework to accelerate the development of an Operator
Operator SDK Three different ways to build an Operator
Our objective Why? Because we can!
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 😁
All the code is available https://github.com/LostInBrittany/lets-dive-into-kubernetes-operator-creation
Aurélie’s Gopher repository https://github.com/scraly/gophers
random-gopher container https://hub.docker.com/r/lostinbrittany/random-gopher
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
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
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…
We also have an API for Gophers https://github.com/LostInBrittany/lets-dive-into-kubernetes-operator-creation /tree/main/gopher-api-and-ui
We also have an API for Gophers
And an UI to see the Gophers in the API https://github.com/LostInBrittany/gophers-api-watcher
To make it easy we deploy on Clever Cloud
In the logs we get the API key
What we want An operator to feed the API with the deployed pods info
And we are doing it in the simplest way In JavaScript, yeah!
Taking as base k8s-operator-node https://github.com/dot-i/k8s-operator-node
Building the gopher operator Let’s switch to VS Code…
That’s all, folks! Thank you all!
Operators are extensions to Kubernetes that simplify application install and management by leveraging on Kubernetes Custom Resources and Controllers. The Kubernetes Operator pattern tries to emulate the role of a human operator, who uses their deep knowledge of the application to install, operate and debug it. The Kubernetes Operators search to automate these tasks and facilitate the whole application life cycle.
Last year at DevOps Barcelona, Aurélie and Horacio showed how to build a Terraform provider, using as example an external API and lots of Gophers. This year they would like to take a similar approach to show you, step by step, how to create a Kubernetes Operator. By taking again as base the Gopher REST API, they will explain the basics of an operator creation, give some pointers on how to do a simple yet efficient operator architecture that manages not only Kubernetes objects but also resources outside Kubernetes, and show you the code and the provider in action.
Will they succeed in this new mission?
Here’s what was said about this presentation on social media.
