Building kubectl plugins with Quarkus | DevNation Tech Talk

Build your own
kubectl plugin
using Quarkus

Sebastien Blanc
● @sebi2706
● sblanc@redhat.com
● Currently Red Hat’s Director of Developer Experience
● Java Champion
● Passion-Driven-Developer with one goal : share his
passion by giving talks that are pragmatic, fun and
focused on live coding

Kubectl > pronunciation ﬁght
Disclaimer
Pronounce “kubectl” as you want :-)

Kubectl > cool, but can i extend it?

Kubectl: tied to core release cycle
Wants to implement a new feature in Kubectl?
So … Forget about it and think about plugins instead ;-)

KuberneteS, an extensible world

Plugins > Why it’s useful?
Extend kubectl with extra functionality
that still feels like kubectl
● e.g. kubectl service-catalog [...]
Encapsulate repetitive workflow
● e.g checking a secret resource, check logs

1. Create a file named kubectl-myplugin
Kubectl plugin > How it works?
15

2. Make it executable
16

3. Put it in your PATH
17

3. Put it in your PATH
4. Run “kubectl myplugin”
18
https://kubernetes.io/docs/tasks/extend-kubectl/kubectl-plugins/

1. How to manage the CLI options and parameters ?
2. How to make it interact with a cluster ?
3. How to quickly bootstrap a project ?
4. How to make it executable ?
5. How to make it fast ?
Kubectl plugin > Using Java ?
19

PLUGIN
PARAMETER
OPTION
Kubectl plugin > Handle parameters and options
20

22

24

//DEPS info.picocli:picocli:4.5.0
import picocli.CommandLine;
import picocli.CommandLine.
Command;
import picocli.CommandLine.
Parameters;
import java.util.concurrent.Callable;
@Command(name = "intro")
class intro implements Callable<Integer> {

What is krew?
● A package manager for kubectl plugins
○ Like “brew” but for kubectl :)
○ Developed summer of 2018 by Google intern
Luk Burchard (@lbb)
● Krew is open sourced, try it:
https://github.com/kubernetes-sigs/krew
33

Krew > useful for users
● Discover kubectl plugins
● Easy way to install plugins
● Update easily plugins
34

Krew > useful for developers
● Make their plugins discoverable
● Easy way to package their plugins for
multiplatforms (Win, Linux, MacOS)
35

Krew > install not published plugins
40
Your plugin is not already published/available on krew
index?
Not problem, you can also install it through Krew!

Krew > install not published plugins
41
Your plugin is not already published/available on krew
index?
Not problem, you can also install it through Krew!

Index:
apiVersion: krew.googlecontainertools.github.com/v1alpha2
kind: Plugin
metadata:
name: season
spec:
homepage: https://github.com/scraly/kubectl-season
shortDescription: Display seasonal emoji randomly before resources name
version: v0.0.3
description: |
This plugin allows you to add randomly a seasonal (halloween, christmas, easter...) emoji
just before the resources name. It's a special seasonal mode.
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
uri: https://github.com/scraly/kubectl-season/archive/v0.0.3.tar.gz
sha256: ee194028b38fd102becc552ebfc7a7f38253acfb949835aa80bb1eb46eed3de8
bin: kubectl-season-0.0.3/kubectl-season
kubectl-season/.krew.yaml
44
Publishing on Krew > manifest ﬁle

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
K8s Object
45

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
Plugin
Info
46

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
Platforms[]
47

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
Match
Platform
48

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
Download
49

kind: Plugin
metadata:
name: season
spec:
version: v0.0.3
description: |
platforms:
- selector:
matchExpressions:
- key: os
operator: In
values:
- darwin
- linux
Plugin
Binary
50

Publishing on Krew > Pull Request
51
https://github.com/kubernetes-sigs/krew-index

Krew > Create your private index & publish into it
New feature: you can create your private index

Krew > our fav plugins
55
> view-secret

56
> view-secret
> view-cert

57
> view-secret
> view-cert
> view-utilization

58
> view-secret
> view-cert
> view-utilization
> neat

Plugin creation > best practices
60
Naming is important
● DON’T: kubectl-version
Not possible to create plugins that
overwrite existing kubectl commands

61
Naming is important
● DON’T: kubectl service
Unclear what the plugin is doing
with service
● DON’T: kubectl open
Unclear what it is opening
● DO: kubectl open-svc
The plugin will open a service :-)

62
Golang
https://github.com/kubernetes/sample-cli-plugin

63
krew-release-bot
https://github.com/rajatjindal/krew-release-bot
Golang

64
krew-release-bot Go releaser
https://goreleaser.com/
Golang

understanding in a visual way
http://gumroad.com/aurelievache & http://dev.to/aurelievache

$ kubectl thank-you
http://bit.ly/kubernetes-plugin-krew-asynconf

$ kubectl apply -f questions.yaml

Qui parle quand ?
● why this talk? (G)
● kubectl (A)
● kubectl plugin (G)
● create a plugin (A)
● krew (G)
● best practices (A)
● sketchnotes (G)
● conclusion (G)
● thank you+feedbacks+questions (A)
👍

Building kubectl plugins with Quarkus | DevNation Tech Talk

Building kubectl plugins with Quarkus | DevNation Tech Talk

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