![Pod
apiVersion: v1
kind: Pod
metadata:
name: pod-example
spec:
containers:
- name: ubuntu
image: ubuntu:trusty
command: ["echo"]
args: ["Hello World"]](https://image.slidesharecdn.com/introductiontokubernetes-180629090214/85/Introduction-to-kubernetes-21-320.jpg)
![Daemonset
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: daemonset-example
spec:
template:
metadata:
labels:
app: daemonset-example
spec:
containers:
- name: daemonset-example
image: ubuntu:trusty
command:
- /bin/sh
args:
- -c
- >-
while [ true ]; do
echo "DaemonSet running on $(hostname)" ; sleep 10 ;
done](https://image.slidesharecdn.com/introductiontokubernetes-180629090214/85/Introduction-to-kubernetes-32-320.jpg)
Introduction to kubernetes
- 1. Introduction to Kubernetes 2018-06-28 - Nardoz Berlin Raffaele Di Fazio - @x0rg
- 2. Agenda ● What is Kubernetes? ● Architecture ● Main concepts with hands on examples
- 3. Pre-check: who doesn’t know what a container is? ● “Containers are an abstraction at the app layer that packages code and dependencies together.” ● They don’t really exist… ○ CGroups ○ Namespaces ● Docker: nice UX on top of running isolated self contained applications ● Immutable artifacts
- 4. Kubernetes ● Open Source container orchestration system ● Inspired by Borg, Omega, Mesos ● Started at Google, donated to CNCF
- 5. The history so far
- 6. The OSS history so far
- 10. Kubernetes architecture API Server Controller manager Scheduler etcd Worker Node (VM) Worker Node (VM) Kubelet Kubelet nginx nginx nginx kube-proxy kube-proxy
- 11. Kubernetes: running an application API Server
- 12. Kubernetes: running an application API Server Deployment yaml
- 13. Kubernetes: running an application API Server Deployment yaml Scheduler
- 14. Kubernetes: running an application API Server Kubelet Deployment yaml Scheduler
- 15. Kubernetes: running an application API Server Kubelet Deployment yaml Scheduler Controller manager
- 16. Kubernetes: running an application https://jvns.ca/blog/2017/07/27/how-does-the-kubernetes-scheduler-work/
- 17. Main Concepts
- 18. Pod ● The “scheduling unit” of Kubernetes ● Doesn’t get restarted when terminates (can be one shot) ● Pods are collection of one or more containers
- 19. Pod in one picture Instance (node 1) Pod 1 Pod 2 Container 1 Container 2 Container 3 Container 4 Instance (node 2) Pod 3 Pod 4 Container 5 Container 6 Container 7 Container 8
- 20. Pod ● Containers in the same pod are guaranteed to be on the same host ● Containers in the same pod can talk via localhost ● Every pod gets a dedicated virtual IP address in the “pod network” ● Analogy: your application instance in AWS
- 21. Pod apiVersion: v1 kind: Pod metadata: name: pod-example spec: containers: - name: ubuntu image: ubuntu:trusty command: ["echo"] args: ["Hello World"]
- 22. Kubernetes patterns: reconciler ● Controllers in Kubernetes are built by implementing the reconciler pattern ○ GetCurrentState() ○ GetDesiredState() ○ Apply() ● Controller manager: enforces deployment replicas
- 23. Deployment ● Defines a single application in Kubernetes handled by the system ● Analogy: Autoscaling Group in AWS ○ You set the desired state, Kubernetes enforces it
- 24. Deployment apiVersion: apps/v1beta1 kind: Deployment metadata: # Unique key of the Deploymentinstance name: deployment-example spec: # 3 Pods should exist at all times. replicas: 3 template: metadata: labels: app: nginx spec: containers: - name: nginx # Run this image image: nginx:1.10
- 25. Demo
- 26. Kubernetes’ overlay networking ● Every pod gets its own IP from a dedicated overlay network ○ Solves the problem of port mapping ○ No NAT needed ● Implemented via software solution (flannel, calico, weave, …) ● Iptables everywhere!
- 27. Service ● Defines how to to reach your app ● Internal Service: cluster valid IP + DNS ● Can use service as Service Discovery (DNS based) ● Label based selection of targets
- 28. Service kind: Service apiVersion: v1 metadata: name: service-example spec: ports: - name: http port: 80 targetPort: 80 selector: app: nginx type: LoadBalancer
- 29. Demo
- 30. ConfigMap & Secrets ● Object containing a K/V storage for configuration purposes ● Can be “mounted”: ○ File ○ Environment variable ● Keep your configuration for the app generic and customize via ConfigMap ● Secret: like a ConfigMap with hidden fields :-)
- 31. DaemonSet ● Run one instance of the pod for each node of the cluster ● Useful mostly for cluster ops ● Ideal for “system agents”
- 32. Daemonset apiVersion: extensions/v1beta1 kind: DaemonSet metadata: name: daemonset-example spec: template: metadata: labels: app: daemonset-example spec: containers: - name: daemonset-example image: ubuntu:trusty command: - /bin/sh args: - -c - >- while [ true ]; do echo "DaemonSet running on $(hostname)" ; sleep 10 ; done
- 33. Demo
- 34. A lot more to cover ● StatefulSets ● ServiceAccounts ● Namespaces ● Quotas ● …. ● Check out: https://kubernetes.io
- 35. If you want to know more https://www.youtube.com/watch?v=WwBdNXt6wO4
- 36. If you want to know more https://www.youtube.com/watch?v=9YYeE-bMWv8&list=PLvmPtYZtoXOENHJiAQc6HmV2jmuexKfrJ
- 37. If you want to know more https://www.youtube.com/watch?v=w34txLmpEuM
- 38. Thank you! Raffaele Di Fazio - @x0rg