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YAML Tips For Kubernetes by Neependra Khare

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Learn the basics of YAML like spacing, maps, lists and some tips and tricks that will help you to write and verify YAMLs for Kubernetes.

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YAML Tips For Kubernetes by Neependra Khare

  1. 1. YAML Tips & Tricks for K8s Neependra Khare, CloudYuga @neependra
  2. 2. About Me - Neependra Khare ● ● ● ● ● ●
  3. 3. Agenda ● YAML Basics ● K8s & YAML ● K8s API Reference ● YAML Tips for K8s
  4. 4. Yet Another Markup Language ● YAML Spec ○ https://yaml.org/spec/1.2/spec.html#id2 777534 ● YAML Maps --- apiVersion: v1 kind: Pod ● YAML List spec: containers: - name: myc1 image: nginx:alpine - name: myc2 image: redis ● Indentation is done with one or more spaces, as long it is maintained ● Should not use Tabs --- !<tag:clarkevans.com,2002:invoice> invoice: 34843 date : 2001-01-23 bill-to: &id001 given : Chris family : Dumars address: lines: | 458 Walkman Dr. Suite #292 city : Royal Oak state : MI postal : 48046 ship-to: *id001 product: - sku : BL394D quantity : 4 description : Basketball price : 450.00 - sku : BL4438H quantity : 1 description : Super Hoop price : 2392.00 tax : 251.42 total: 4443.52 comments: Late afternoon is best.
  5. 5. Some Issues With YAML ● Define the YAML country_codes: united_states: us ireland: ie norway: no ● Load the YAML in Ruby require 'yaml' doc = <<-ENDYAML country_codes: united_states: us ireland: ie norway: no ENDYAML puts YAML.load(doc) ● Output {"country_codes"=>{"united_states"=>"us", "ireland"=>"ie", "norway"=>false}} YAML Reference ● Define name: &speaker Neependra presentation: name: AKD speaker: *speaker ● Reference Later name: "Neependra" presentation: name: "AKD" speaker: "Neependra" ● What would happen with this? a: &a ["a", "a", "a"] b: &b [*a,*a,*a] c: &c [*b, *b, *b]
  6. 6. Why are we stuck with YAML? Watch Joe Beda’s talk : I am Sorry about The YAML.
  7. 7. Why YAML over JSON ? ● YAML is superset of JSON ● More readable ● Takes less space ● Allows comments apiVersion: v1 kind: Pod metadata: name: mypod #name of the Pod labels: app: nginx spec: containers: - name: nginx-demo image: nginx:alpine ports: - containerPort: 80 { "apiVersion": "v1", "kind": "Pod", "metadata": { "name": "mypod", "labels": { "app": "nginx" } }, "spec": { "containers": [ { "name": "nginx-demo", "image": "nginx:alpine", "ports": [ { "containerPort": 80 } ] } ] } } Configuration in YAML Configuration in JSON
  8. 8. K8s API Reference
  9. 9. API Group Core API Group Other API Groups
  10. 10. Object Model ● Use YAML or JSON file to define object ● We define the desired using spec field apiVersion: v1 kind: Pod metadata: name: mypod namespace: default spec: containers: - name: myc image: nginx:alpine
  11. 11. Object Model ● Use YAML or JSON file to define object ● We define the desired using spec field ● status field is managed my Kubernetes, which describes the current state of the object apiVersion: v1 kind: Pod metadata: name: mypod namespace: default spec: containers: - name: myc image: nginx:alpine status: …… ……
  12. 12. Tip #1 Combine Multiple YAML files into One apiVersion: apps/v1 kind: Deployment metadata: name: rsvp spec: replicas: 1 ...
  13. 13. Tip #1 Combine Multiple YAML files into One apiVersion: apps/v1 kind: Deployment metadata: name: rsvp spec: replicas: 1 ... --- apiVersion: v1 kind: Service metadata: name: rsvp … --- apiVersion: networking.k8s.io/v1 kind: Ingress metadata: …..
  14. 14. Tip#2 Use Quotes apiVersion: v1 kind: Pod metadata: name: mypod labels: app: nginx spec: containers: - name: nginx-demo image: nginx:alpine env: - name: INDIA value: IN - name: NORWAY value: NO ports: - containerPort: 80 root@master:~# k apply -f pod.yaml Error from server (BadRequest): error when creating "pod.yaml": Pod in version "v1" cannot be handled as a Pod: v1.Pod.Spec: v1.PodSpec.Containers: []v1.Container: v1.Container.Env: []v1.EnvVar: v1.EnvVar.Value: ReadString: expects " or n, but found f, error found in #10 byte of ...|,"value":false}],"im|..., bigger context ...|":"INDIA","value":"IN"},{"name":"NORWAY","value":fa lse}],"image":"nginx:alpine","name": "nginx-demo",|...
  15. 15. Tip#2 Use Quotes apiVersion: v1 kind: Pod metadata: name: mypod labels: app: nginx spec: containers: - name: nginx-demo image: nginx:alpine env: - name: INDIA value: IN - name: NORWAY value: “NO” ports: - containerPort: 80 apiVersion: v1 kind: Pod metadata: name: mypod labels: app: nginx spec: containers: - name: nginx-demo image: nginx:alpine env: - name: VERSION value: “10.3” - name: NORWAY value: “NO” ports: - containerPort: 80
  16. 16. Tip#3 - Use YAML Reference apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deploy spec: replicas: 3 selector: matchLabels: &labelsToMatch app: nginx env: dev template: metadata: labels: *labelsToMatch spec: containers: - name: nginx image: nginx:1.9.1 ports: - containerPort: 80 apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deploy spec: replicas: 3 selector: matchLabels: app: nginx env: dev template: metadata: labels: app: nginx env: dev spec: containers: - name: nginx image: nginx:1.9.1 ports: - containerPort: 80
  17. 17. Tip#4 - Use YAML Linters, IDE Plugins ● Online ○ http://www.yamllint.com ● Offline ○ Yamllint CLI ■ https://github.com/adrienverge/yamllint ○ yq ■ https://github.com/mikefarah/yq ● IDE Plugins ○ VSCode ■ https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml ○ IntelliJ ■ https://www.jetbrains.com/help/idea/code-style-yaml.html
  18. 18. Thanks @neependra
  19. 19. References ● https://tanzu.vmware.com/developer/blog/the-hate-for-yaml-the-hammer -or-the-nail/ ● https://www.mirantis.com/blog/introduction-to-yaml-creating-a-kubernete s-deployment/

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