The document provides tips and tricks for using YAML with Kubernetes, including basic syntax, how to define and load YAML, and references to both YAML and Kubernetes API. It emphasizes the advantages of YAML over JSON, such as readability and support for comments, and offers practical tips for structuring YAML files effectively. Additionally, it includes examples of common YAML structures for Kubernetes resources and suggestions for tools to validate YAML syntax.

1. YAML Tips & Tricks for K8s
Neependra Khare, CloudYuga
@neependra

2. About Me - Neependra Khare
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3. Agenda
● YAML Basics
● K8s & YAML
● K8s API Reference
● YAML Tips for K8s

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. 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. Why are we stuck with YAML?
Watch Joe Beda’s talk : I am Sorry about The YAML.

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. K8s API Reference

9. API Group
Core API Group
Other API Groups

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. 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. Tip #1 Combine Multiple YAML files into One
apiVersion: apps/v1
kind: Deployment
metadata:
name: rsvp
spec:
replicas: 1
...

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. 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. 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. 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. 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. Thanks
@neependra

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/