This document provides an overview of Kubernetes and OpenShift for developers. It discusses Kubernetes basics like pods, deployments, services and labels. It also covers local development approaches like using Docker Compose, testcontainers and local Kubernetes clusters. Additional topics include Helm, operators, service meshes and tools for real-time changes in Kubernetes.

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Kubernetes (and OpenShift) for Developers
Jeremy Davis
@argntprgrmr

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Try this at home!
Itwon’thurtmuch
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Topics
Kubernetes Basics
Local Development for Distributed Apps
Kubernetes Friendly Stuff
The next 45 minutes of your life will be occupied with this stuff
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Why?
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Aside from the obvious resume advantages

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Why?
Speed, Microservices
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Aside from the obvious resume advantages

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BuildingBlocks
Kubernetes
Basics

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kubectl is really important
kubectl <command> --help
kubectl explain <object>
kubectl create -f <filename>
Kubectl get all -o yaml
https://kubernetes.io/docs/reference/kubectl/kubectl/
kubectl

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Pods, Deployments, Services
Kuberenetes
Objects
Pods
ReplicaSets
Deployments
Ingress
ConfigMaps

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EXISTING
AUTOMATION
TOOLSETS
SCM
(GIT)
CI/CD
INGRESS/SERVICE LAYER
ROUTING LAYER
PERSISTENT
STORAGE
REGISTRY
RHEL
NODE
c
RHEL
NODE
RHEL
NODE
RHEL
NODE
RHEL
NODE
RHEL
NODE
C
C
C C
C
C
C CC C
RED HAT
ENTERPRISE LINUX
MASTER
API/AUTHENTICATION
DATA STORE
SCHEDULER
HEALTH/SCALING
PHYSICAL VIRTUAL PRIVATE PUBLIC HYBRID
Under the hood
Kubernetes (and OpenShift) Architecture
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Pods
Basic execution unit
One or more containers (usually only one)
Unique IP address
Ephemeral, disposable
No naked pods
First things first
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
labels:
app: myapp
spec:
containers:
- name: myapp-container
image: busybox
command: ['sh', '-c', 'echo
Hello Kubernetes! && sleep
3600']
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Replica Sets
Desired number of pods
Multiple Things
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
labels:
app: myapp
spec:
containers:
- name: myapp-container
image: busybox
command: ['sh', '-c', 'echo
Hello Kubernetes! && sleep
3600']
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Deployments
Describes desired state of pods
Creates ReplicaSets
Recreate or RollingUpdate
Rollbacks
Superset of the Previous Two
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
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Services
Exposes a set of pods to the network
Pods Together
apiVersion: v1
kind: Service
metadata:
name: the-service
spec:
selector:
app: quarkus-demo
ports:
- protocol: TCP
port: 80
targetPort: 8080
type: NodePort
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Labels
Everything should uses labels
No Naked Pods!
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Logs, Exec
Execute code in the pod
Like ssh
Bash, curl
These are really useful
kubectl exec -i -t $PODID
/bin/bash
kubectl logs PODNAME
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HowtoWorkwiththisStuff
Local
Development
for Distributed
Applications

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Remember What App Servers Were Like in 2002?
Developing for Kubernetes (and OpenShift)
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It’s different from what you’re used to and often annoying
Essentially the same way you
have always developed
Local Dev/Remote Kubernetes
Dependent services running
in an external cluster
Local Kubernetes
Dependent services running
locally in containers
Local With Containers

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Farm to Laptop
Local Dev
Remote Kubernetes
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JUnit
Wiremock
Mockito
Jenkins
Tekton
Familiar
Fast iteration locally
Testing and integration is cumbersome

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Local with Containers
Probably the Sweet Spot
docker-compose up
Test Containers
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Reasonably familiar
Good inner loop
Not aligned with production (or integration) but a bit closer than local
Integration is more cumbersome

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YouCanRunTheseonYourLaptop
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Docker Compose and
Testcontainers

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Local Kubernetes
Less fun, but probably necessary
minikube start
skaffold dev
odo push
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Minikube
Kind
Code Ready Containers
K3d
MicroK8s

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YouCanRunTheseonYourLaptop
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RealTimeChangesinKubernetes
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Helm
The Package Manager for Kubernetes
Charts
Repositories
Releases
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About Operators
Sort of like Helm Charts
OperatorHub
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Remote Kubernetes
Painful and a Lot Like 2002
Jenkins
Harness
Spinnaker
Tekton
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Slow inner loop
Low productivity
DIfferent development and debugging envirnments

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You’reinthehomestretch!
Kubernetes
Friendly Stuff

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(Relatively) New Stuff
Health checks
Readiness checks
Fault tolerance/Circuit breakers
Web client
MostlyJustMicroservicesStuffHere
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And Service Mesh
CrossCuttingConcerns
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Thank You!
Devnexus2020
Jeremy Davis
@argntprgrmr
github.com/jeremyrdavis

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Stuff You Can Use Later
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References
Kubernetes API reference docs:
https://kubernetes.io/docs/reference/generated/kubernetes-api/
Red Hat Developers (lots of great Kubernetes/OpenShift and other content)
https://developers.redhat.com/
Kubernetes Patterns: http://shop.oreilly.com/product/0636920242598.do
9 Steps to Awesome with Kubernetes (Great tutorial and workshop)
http://bit.ly/9stepsawesome
https://github.com/burrsutter/9stepsawesome
https://www.youtube.com/watch?v=ZpbXSdzp_vo&t=3239s

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Stuff You Can Use Later
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Tools
Local Development
kubectl: https://github.com/kubernetes/kubectl
https://kubernetes.io/docs/reference/kubectl/cheatsheet/
Docker Desktop: https://www.docker.com/products/docker-desktop
Docker Compose: https://docs.docker.com/compose/
Test Containers: https://www.testcontainers.org/

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Stuff You Can Use Later
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Tools
Local Kubernetes
Minikube: https://github.com/kubernetes/minikube
Kind: https://kind.sigs.k8s.io/docs/user/quick-start/
K3S: https://k3s.io/
MicroK8s: https://microk8s.io/
Code Ready Containers: https://github.com/code-ready/crc

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Stuff You Can Use Later
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Service Mesh
Istio:: https://istio.io/
Linkerd:: https://linkerd.io/
Solo.io: https://www.solo.io/
Aspen Mesh: https://aspenmesh.io/