Kubernetess

Source tutorial

https://www.youtube.com/watch?v=X48VuDVv0do&list=PPSV

Terminology

Pod - the smallest unit of kubernetess cluster.

Replicaset - is managing replicas of the pod. In practice you don't have to create them, update, delete or manage in any way.

Installation on mac

brew install minikube
brew install docker

Starting

minikube start --vm-driver=docker

Debugging

Getting status of running nodes

kubectl get nodes
minikube status
kubectl get services

kubectl get pod
kubectl get pod -o wide //more concrete pod info

kubectl get replicaset

kubectl get deployment [deployment] -o yaml
kubectl get deployment [deployment] -o yaml > [savefilename.yaml]


kubectl logs [podname]
kubectl describe pod [podname]
kubectl descripe service [service name]

kubectl get all

Creating kubernetess components

kubectl create -h.  // -h help,

Demo deployment - Ngingx

Create deployment has all the information or blueprints to create the pod. The most basic (minimalistic) configuration for deployment - name and image to use

kubectl create deployment nginx-depl --image=nginx
kubeclt get deployment //to see list of deploymnets
kubectl logs nginx-depl-[podname]

Edit deployment

kubectl edit deployment nginx-depl

Demo deployment - Mongo

kubectl create deployment mongo-depl --image=mongo
kubectl logs mongo-depl-[podname]

Exec

-it - means interactive terminal

kubectl exec -it [podname] -- bin/bash
exit //for leaving container

Deleting

kubectl get deployment
kubectl delete deployment [deployment]
kubectl get pod // you should see Pod in status [Terminating]

Apply config file

kubectl apply -f nginx-deployment.yaml

Demo kubernetess file:

http://kubernetes.io/docs/tasks/run-application/run-stateless-application-deployment

Kubernetess file has following structure:

1. metadata
2. specification
3. status - automatically generated and added by Kubernetess

Types of file:

• component
• service - opens component to the outer world

Namespaces

kubectrl api-resources --namespaced=false //shows resources without namespace
kubectrl api-resources --namespaced=true 

Utilities and plugins

kubectx

brew install kubectx
kubens // list kubernetess namespaces

Ingress

Component which should be used in produciton. Instead of direct expose to the service.

--watch - to not refresh table, this one waits, and refresh console for you...

kubectl get ingress -n kubernetes-dashboard --watch

Helm

Package manager for kuberneters.

Tiller

Keeps histroy of helm charts executions. Removed in Helm 3.