k8s by example talk at oSC 23 How to development apps for Kubernetes

1. k8s by example
Dr. Christoph Zimmermann
27.5.2023 @ oSC23

2. 2
cat /etc/motd
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Foundation
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Prerequisites
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The code base
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Packaging
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Deployment
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H/A & resilience (cluster access, Ingress, etc)
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Q & A

3. 3
whoami
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PhD in reflective operating system architectures
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First crush on Linux: kernel 0.95
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Tech support + more @ FraLUG
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Podcaster
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Hobbies include:
– SDLC
– IT security and other forms of black art
– Other peoples’ computers
– Consulting
linuxinlaws.eu

4. 4
sum recap
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5. 5
pip install -r requirements.txt
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Posix-compliant OS (Linux, *BSD, etc)
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Container run-time
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k8s of choice:
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minikube (/minishift): single node cluster
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Docker Desktop CE: similar
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kind: cluster in containers
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DYI:
1.Create at least 2 VMs (Xen, kvm, etc.)
2.Create network bridge between VMs
3.Install container runtime (containerd, etc.) in VMs
4.Bootstrapping the cluster with kubeadm
(5. Network: Flannel or similar depending on requirements)
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Ingress controller and image registry installed

6. 6
man svc
Source: https://stackoverflow.com/questions/41509439/whats-the-difference-between-clusterip-nodeport-and-loadbalancer-service-types

7. 7
kubectl get ingress
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For Docker k8s:
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Install software:
kubectl apply -f
https://raw.githubusercontent.com/kubernetes/ingress-nginx/co
ntroller-v1.7.1/deploy/static/provider/cloud/deploy.yaml
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Check if ontroller pod up & running:
kubectl get pods –namespace=ingress-nginx
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Fully operational:
kubectl wait --namespace ingress-nginx --for=condition=ready
pod --selector=app.kubernetes.io/component=controller
--timeout=60s
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Ingress details (external port!):
kubectl get service ingress-nginx-controller -n ingress-nginx

8. 8
docker ps -a | fgrep registry
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Install local image registry:
docker run -d -p 6000:5000 --restart=always
--name registry registry:2

9. 9
kubectl top
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Optional: metrics-server (for Docker k8s)
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wget https://github.com/kubernetes-sigs/metrics-
server/releases/latest/download/components.yaml
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Change
--kubelet-use-node-status-port
- --metric-resolution=15s
image: registry.k8s.io/metrics-server/metrics-server:v0.6.3
to
--kubelet-use-node-status-port
- --metric-resolution=15s
- --kubelet-insecure-tls
image: registry.k8s.io/metrics-server/metrics-server:v0.6.3
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kubectl apply -f components.yaml
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Check with: kubectl top

10. 10
kubectl apply -f
https://github.com/monochromec/k8s

11. 11
sum /etc/motd
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k8s:
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Scaleability & H/A: easily incorporated in apps
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Batteries included: application monitoring framework
OOTB
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Local machine -> massive deployments in clouds
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Challenges:
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Hybrid / multi-cloud config tends to be complex
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Security
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Multi-arch issues (amd64 vs. aarch64, etc)

12. 12
cat /usr/local/share/k8s/propaganda
<one_more_thing>
</one_more_thing>
+
2023

13. 13
apropos
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Go app: https://www.coding-bootcamps.com/blog/build-containerized-
applications-with-golang-on-kubernetes.html
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k8s documentation: https://kubernetes.io/docs/home
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k8s locale image registry: https://github.com/SeldonIO/k8s-local-docker-
registry
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Docker Desktop: https://www.docker.com/products/docker-desktop
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minikube: https://minikube.sigs.k8s.io/docs/start
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Kind: https://kind.sigs.k8s.io
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nginx ingress installation:
https://kubernetes.github.io/ingress-nginx/deploy/#quick-start
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DYI k8s: https://www.hostafrica.com/blog/servers/kubernetes-cluster-
debian-11-containerd/

14. 14
irssi
Q & A