cdk8s, a cure for YAML

Presentation given at the CNCF & Kubernetes meetup Belgium on 08/02/2023

Transcript

1. cdk8s, a YAML alternative cure Vincent Van der Kussen Thursday, February 8, 2023 Belgium Kubernetes & CNCF Meetup
2. #whoami ▪ Retired Linux engineer ▪ Freelance “cloud native” engineer ▪ @vincentvdk (Twitter/Mastodon/Github) ▪ Co-owner of Autops
3. Let’s take a step back
4. Plain YAML Ok for small things Gets harder as you grow • copy/paste • Manual updates are complex
6. Source: https://kubernetespodcast.com/episode/012-kubernetes-origins/ Also intersting Kubernetes: The Documentary (YouTube) “And so there was always this thinking that there would be higher-level abstractions that would help to sort of take the intent and translate that into those API objects. I'm kind of horrified that we're still authoring those API objects directly by hand because we never intended those things to be human consumable.” - Joe Beda
7. What are our options?
10. And many more (Terraform, Ansible, Pulumi,...)
11. What is “wrong” with these tools?
12. • Still manipulate YAML in some way • Testing? • No IDE/Editor integration − Linting, code completion, navigation, .. • Re-usability • Simplicity
15. Use code Define Kubernetes resourced using familiar programming languages.
16. Share as libraries Share reusable components through code libraries Code libraries are easier to share and maintain than templates. CDK8s allows you to standardize how to do things in Kubernetes and share this across your organization
17. High level overview
18. Demo
19. Reusable components (Constructs)
20. Construct levels • L0 – ApiObject − 1-to-1 mapping with Kubernetes objects − You will probably never use these • L1 – Higher level (ex: Deployment) − cdk8s+ • custom – ex: MyCompanyService − Collection of L1
21. cdk8s+ 1 apiVersion: networking.k8s.io/v1beta1 1 apiVersion: networking.k8s.io/v1
22. 1 import { Construct } from 'constructs'; 2 import { App, Chart, ChartProps } from 'cdk8s'; 3 import {CompanyService} from './lib/company-service' 4 5 export class MyChart extends Chart { 6 constructor(scope: Construct, id: string, props: ChartProps = { }) { 7 super(scope, id, props); 8 9 10 new CompanyService(this, 'NewService', { 11 name: 'foo', 12 image: 'nginx' 13 }) 14 15 } 16 } 17 18 const app = new App(); 19 new MyChart(app, 'example2'); 20 app.synth(); 21
23. Testing
24. 1 import {MyApp} from './main'; 2 import {Testing} from 'cdk8s'; 3 4 describe('Placeholder', () => { 5 test('Label shoud match', () => { 6 const app = Testing.app(); 7 const chart = new MyApp(app, 'test-chart', {env: 'production'}); 8 const results = Testing.synth(chart) 9 expect(results[0]).toHaveProperty('metadata.labels.env', 'production') 10 }) 11 12 test('Production needs 2 replicas', () => { 13 const app = Testing.app(); 14 const chart = new MyApp(app, 'test-chart', {env: 'production'}); 15 const results = Testing.synth(chart) 16 //expect(results[0]).toHaveProperty('spec.replicas', 2) 17 const deploy = results.filter(v => { return v.kind == 'Deployment'}) 18 expect(deploy[0]).toHaveProperty('spec.replicas', 2); 19 }) 20 }); 21
25. Helm support 1 class MyChart extends cdk8s.Chart { 2 constructor(scope: Construct, id: string) { 3 super(scope, id); 4 5 const redis = new Helm(this, 'redis', { 6 chart: 'bitnami/redis', 7 values: { 8 sentinel: { 9 enabled: true 10 } 11 } 12 }); 13 } 14 } 1 const master = redis.apiObjects.find(o => o.name === 'foo-redis-master'); 2 master.metadata.addAnnotation('my.annotation', 'hey-there');
26. 1 export class Redis extends cdk8s.Chart { 2 3 public readonly password: SecretValue; 4 5 constructor(scope: Construct, id: string) { 6 super(scope, id); 7 8 const redis = new Helm(this, 'redis', { 9 chart: 'bitnami/redis', 10 values: { 11 sentinel: { 12 enabled: true 13 } 14 } 15 }); 16 } 17 18 // Exporting the secret created by Helm chart 19 this.password = { 20 secret: secret.fromSecretName(redis.releaseName), 21 key: 'redis-password' 22 }; 23 } 1 const redis = new Redis(this, 'redis') 2 // 3 env: { 4 REDIS_PASWORD: EnvValue.fromSecretvalue(redis.password) 5 }
27. Escape Hatches 1 import { JsonPatch } from 'cdk8s'; 2 apiObject.addJsonPatch(JsonPatch.replace('/foo', 'bar')); 3 apiObject.addJsonPatch(JsonPatch.add('/foo/bar/0', { bar: 123 }));
28. Import CRD’s
29. Thank you! Contact vincent@autops.eu https://www.autops.eu https://mastodon.social/@vincentvdk Web : cdk8s.io Slack : cdk.dev GitHub : https://github.com/awslabs/cdk8s