This document summarizes a presentation about applying the 12 factor app methodology to Kubernetes. It discusses each of the 12 factors and how they relate to Kubernetes concepts like pods, services, configmaps, secrets and more. The presentation encourages embracing the Kubernetes paradigm, writing stateless and cloud-ready code, using infrastructure as code practices, and leveraging the Kubernetes community.

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12 Factors Kubernetes
by Etienne Coutaud
Devoxx 2018

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whoami ?
Consultant Devops @OCTO Technology
Certified Kubernetes Administrator (CKA)
https://github.com/etiennecoutaud
@etiennecoutaud

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#1 1 Pod = 1 or n containers

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cache shard n
Pods multi containers Designs Patterns
Sidecar Ambassador Adapter
Extend pod function Represent (proxy) Expose and normalize
App
Log Streaming
App
Cache Proxy
App
Monitoring adapter
Logs
Log aggregator cache shard 1
Monitoring service
cache shard 1

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#2 Labels everywhere

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Labeling for technical and management reasons
LabelSelector
Label
LabelSelector
Label Label
app=php app=java app=php
env=prodtype=dbapp=node
env=dev version=1.1

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#3 Infrastructure as Code &
code versionning

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Infrastructure code is code
docker pipeline
kubernetes pipeline
App code
(Dockerfile)
infrastructure
code
(*.yml)
Image
docker
Ressource
k8s
Ressource
k8s
Ressource
k8s
Registry
cluster k8s
build push
push apply

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#4 Use Service to expose

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Many types of service
10
ClusterIP
NodePort
LoadBalancer
Headless
(ClusterIP=None)
External

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#5 Use ConfigMaps and Secrets
to manage configuration

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Configuration as a Service
Namespace Kubernetes
cluster wide configuration
configmap.yml
secret.yml
App configuration
configmap.yml
secret.yml
Devs
Admins

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#6 Limits & Request for
resources management

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Improve scheduling and protect against fork bomb
250Mo
1
RAM
CPU
Limits
1GO
2
Request 1
RAM
CPU
1,5GO
2

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#7 Pods Lifecycle

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Use deployment to manage pods
deployment.yml
replicaSet description
Pods description
$ kubectl apply -f deployment.yml
Manage rolling update
Manage replicas
deployment description

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#8 LivenessProbe to monitor
your pods status

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Become resilient
LivenessProbe
ReadinessProbe
OK OK KO
KO KO OK
Set up probes
Pod is destroy and restart
Pods go out of load
balancing pool

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#9 Latest is not a version

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Build Once Run Everywhere
Feature Branch DEV RE7 PPROD PROD
myapp myapp myapp myapp myapp
34u67gfx6 dev re7 pprod latest
merge/promote promote promote tag/promote
v1.0

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#10 Pods are stateless
(If they don’t have to)

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What happens if my pod is stateful ?
Etat
horizontal scaling
EtatEtat Etat
round robin

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#11 Volumes are mount on a
distributed storage system

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500Mo
Kubernetes stateful way architecture
Distributed storage
1Go 1Go 5Go 10Go 10Go 50Go
3Go 20Go

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#12 Mind your code 12 factor
app compliant

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12 good practices by Heroku (PaaS)
Main factors :
● Use version control system to manage your code
● Expose an healthcheck URL in your app
● Thinks your app stateless
● Use variables environment to configure your app
● Log on stdout/stderr
● Manage graceful shutdown/start

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Take away !
● Embrace Kubernetes paradigm
● Don’t bring infrastructure complexity into your code
● Think your application “cloud ready” for better management
● Don’t install Kubernetes, Prefer Managed Services if you can
● “Think Big, Start Small”
● Use Kubernetes community

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Thank you !
@etiennecoutaud
#12factorsk8S
https://github.com/etiennecoutaud/12factorsK8s
https://blog.octo.com/the-twelve-factors-kubernetes
https://github.com/octo-technology/kubernetes-icons