Kubernetes Crash Course

Kubernetes Crash Course Blog Post(KR) - no link yet

Prerequisite

Requirement: Mac model 2010+, OS 10.12+

Docker

Install docker for mac.
Follow docker guide to increase resource limit(need to set memory to 8GB+).

Go

Install Go download from [golang.org]
You can manage Go verions with [gvm]

Kubectl

### Install with Homebrew on macOS
brew install kubernetes-cli
### download kubectl 1.16.0
curl -LO https://storage.googleapis.com/kubernetes-release/release/v1.16.0/bin/darwin/amd64/kubectl
chmod -x ./kubectl
mv ./kubectl /usr/local/bin/kubectl
### if kubectl isn't executable
chmod 755 /usr/local/bin/kubectl

KIND

Refer to KIND for more details

GO111MODULE="on" go get sigs.k8s.io/kind@v0.5.1
export PATH="$PATH:$(go env GOPATH)/bin"

Aliases

alias k='kubectl'
alias chrome="/Applications/Google\\ \\Chrome.app/Contents/MacOS/Google\\ \\Chrome"

Useful Tools

kubectl command shell [auto-completion]

### for oh-my-zsh
plugins=(... kubectl)

k8s context/namespace changer [kubectx/kubens]
Awesome k8s shell prompt kube ps1
Very cool k8s CLI manage tool [k9s]
Multiple pods log tool for k8s [stern]

Practice

Create k8s multi-node cluster with KIND

Will create 1 master and 2 worker nodes.

kind create cluster --name kind-m --config kind-test-config.yaml

Change k8s config

Add configs from ‘.kube/kind-config-kind-m’ to ‘.kube/config’ file
or:

export KUBECONFIG="$(kind get kubeconfig-path --name="kind-m")"

Note: k8s config file may contain multiple configs.

Verify k8s cluster

kubectl cluster-info
kubectl get nodes
kubectl get pods --all-namespaces

Install metrics-server

Refer to metrics-server for more information

kubectl apply -f ./metrics-server

Install Ingress-nginx

Installation Guide

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
### create service with nodeport 32080, 32433
kubectl apply -f ./ingress-nginx/

Deploy MariaDB(MySQL) for Wordpress - Stateful Sets

Deploy MariaDB:

kubectl create namespace wordpress
kubectl apply -f ./mysql
### Check Stateful Sets
kubectl get sts -n wordpress
kubectl describe sts mysql -n wordpress

Deploy Wordpress - Deployment

Deploy Wordpress:

### get you local ip
IP=$(ifconfig | grep "inet " | grep -Fv 127.0.0.1 | awk '{print $2}')
### replace ingress host with your IP
sed -i.bak "s/host.*/host: blog."$IP".nip.io/g" ./wordpress/ingress.yaml
kubectl apply -f ./wordpress
### edit deployment
kubectl edit deploy wordpress
### port forward to check if wordpress is running correctly
WPOD=$(kubectl get -n wordpress pod -l app=wordpress -o jsonpath="{.items[0].metadata.name}")
kubectl port-forward pod/$WPOD 8090:80 -n wordpress

Scale in/out Deployments:

kubectl scale deploy wordpress --replicas=3 -n wordpress
kubectl scale deploy wordpress --replicas=1 -n wordpress
### check services for wordpress
kubectl get svc -n wordpress
### check ingress
kubectl get ingress -n wordpress
### other commands
k explain deployment --recursive
k explain svc --recursive
k get pods -o wide --sort-by="{.spec.nodeName}"

Expose Ingress

Intall socat to expose nodeport on local 80 port:

docker run -d --name kind-proxy-80 \
--publish 80:80 \
--link kind-m-control-plane:target \
alpine/socat \
tcp-listen:80,fork,reuseaddr tcp-connect:target:32080

Test

Test with your own DNS:

chrome http://blog.$IP.nip.io

Delete resources and cluster

kubectl --namespace=wordpress delete --all
kubectl delete --namespace wordpress
kind delete cluster --name kind-m
### remove socat
docker rm -f kind-proxy-80

Extra

Web UI(Dashboard)

Install [dashboard]:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.0.0-beta4/aio/deploy/recommended.yaml
### Run below to fix auth
k apply -f ./dashboard
### Run below and copy hash code from token:  
./dashboard/getsecret.sh
### Run below from another terminal:
k proxy

Click this /proxy/">link to open dashboard in your web browser.

To disable session time-out:

kubectl edit deployment kubernetes-dashboard -n kube-system
### add following after arg:
- args:
  - --token-ttl=0

Autoscaler

### metrics-server must be running
kubectl apply -f ./extra

Demo - ASCIINEMA

Debug

Refer to K8S Debug Services for details

# Run alpine image to troubleshoot
kubectl run -it --rm --restart=Never alpine --image=alpine sh
# lookup service
nslookup wordpress
# check svc name/IP
wget -SO- wordpress:8081
wget -SO- <SVC_IP>:8081
# check pod endpoint
wget -SO- <POD ID:80>

Blogs and Documentations

subicura님의 쿠버네티스 시작하기 블로그

Kubernetes Documentation(KR)

K8S Deep Dive: API Server Part1, Part2, Part3

Google Container(KR)

이어형님 딥다이브

Dockerfile Best Practices

[kubectx/kubens]:
https://github.com/ahmetb/kubectx

[auto-completion]:
https://kubernetes.io/docs/tasks/tools/install-kubectl/?source=#enabling-shell-autocompletion

[dashboard]:
https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/

[KIND]:
https://kind.sigs.k8s.io/docs/user/quick-start

[golang.org]:
https://golang.org/dl/

[gvm]:
https://github.com/moovweb/gvm

[Homebrew]:
https://brew.sh/

[k9s]:
https://k9ss.io/?fbclid=IwAR0MQO9yBF5iKpJlDkuSNtrWGy72zK81I-j071lrKQsV1DLhloOMknOLd64

[stern]:
https://github.com/wercker/stern