Kubernetes in a nutshell - tutorial for beginners

Overview

This repo contains exercises, which together with this blog post, will help you start working with Kubernetes (k8s). You can look at my Kubernetes troubleshooting guide, which covers the most common beginner questions and mistakes.

Prerequisites

• Docker
• Minikube
  • macOs: brew cask install minikube
• VirtualBox (for minikube)
  • macOs: brew cask install virtualbox

Check the tools:

# --- check docker: running containers ---
docker ps

# output:
CONTAINER ID	IMAGE	COMMAND		CREATED		STATUS		PORTS		NAMES

# --- check minikube: version & run minikube ---
minikube -v
minikube start
kubectl get all

# output:
There is a newer version of minikube available (v1.0.0).  Download it here:
https://github.com/kubernetes/minikube/releases/tag/v1.0.0

To disable this notification, run the following:
minikube config set WantUpdateNotification false
😄  minikube v0.35.0 on darwin (amd64)
🔥  Creating virtualbox VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
💿  Downloading Minikube ISO ...
 184.42 MB / 184.42 MB [============================================] 100.00% 0s
📶  "minikube" IP address is 192.168.99.100
🐳  Configuring Docker as the container runtime ...
✨  Preparing Kubernetes environment ...
💾  Downloading kubelet v1.13.4
💾  Downloading kubeadm v1.13.4
🚜  Pulling images required by Kubernetes v1.13.4 ...
🚀  Launching Kubernetes v1.13.4 using kubeadm ...
⌛  Waiting for pods: apiserver proxy etcd scheduler controller addon-manager dns
🔑  Configuring cluster permissions ...
🤔  Verifying component health .....
💗  kubectl is now configured to use "minikube"
🏄  Done! Thank you for using minikube!


NAME				TYPE		CLUSTER-IP		EXTERNAL-IP		PORT(S)		AGE
service/kubernetes  ClusterIP	x.x.x.x			<none>			443/TCP		2m

Prepare your environment

To start working with k8s, run these commands:

# Start minikube:
minikube start

# Use Docker at the command line of your local machine 
# to communicate with the Docker daemon inside the minikube.
# This command exports docker env variables and configures your shell. 
# The docker host url will point to the minikube's one. 
# From now, everytime when we build a new docker image, 
# it will be visible inside the minikube.
# When you create a deployment and provide a docker url to your image,
# it will take the image previously built by you.
eval $(minikube docker-env)

# Enable the NGINX Ingress controller:
minikube addons enable ingress

# Check if the Ingress controller is there:
kubectl get po -n kube-system

# Add this line to your /etc/hosts:
# 192.168.99.XXX - it's IP of the minikube cluster. 
# You can simply check it by running: minikube ip
# (replace your app names with BACKEND_NAME and FRONTEND_NAME)
192.168.99.XXX       backend.domain.com frontend.domain.com

Deploying database

kubectl apply -f database/deployment/database-deployment.yaml
kubectl apply -f database/deployment/database-service.yaml

Deploying backend

# build backend docker image
docker build -t backend:v1 ./backend

# deploy
kubectl apply -f ./backend/deployment/backend-deployment.yaml
kubectl apply -f ./backend/deployment/backend-service.yaml
kubectl apply -f ./backend/deployment/backend-ingress.yaml

Deploying frontend

# build backend docker image
docker build -t frontend:v1 ./frontend

# deploy
kubectl apply -f ./frontend/deployment/frontend-deployment.yaml
kubectl apply -f ./frontend/deployment/frontend-service.yaml
kubectl apply -f ./frontend/deployment/frontend-ingress.yaml

This docker images can take some time since npm install is running inside. If you want to save your time in the future (you will build the image a couple of times), replace the Dockerfile with the following one:

FROM nginx

COPY ./build /etc/nginx/html
COPY ./nginx.conf /etc/nginx/nginx.conf
WORKDIR /etc/nginx

EXPOSE 80

CMD ["nginx", "-g", "daemon off;"]

and then run:

cd frontend

# install dependencies
npm install

# build production code
npm run build

# build backend docker image
docker build -t frontend:v1 .

Health check:

Proof (1)

# display all resources deployed on k8s
kubectl get all

# display deployments/pods/services/ingresses deployed on k8s
kubectl get deployment # or kubectl get deployments or kubectl get deploy
kubectl get pod # or kubectl get pods or kubectl get po
kubectl get service # or kubectl get services or kubectl get svc
kubectl get ingress # or kubectl get ingresses or kubectl get ing

# or 
kubectl get deploy,po,svc,ing

Proof (2)

Go to minikube dashboard and see your deployments there.

Proof (3)

Go to backend.domain.com. Under the main root (/), you should see: "backend works".

Proof (4):

Go to frontend.domain.com . Now, we should be able to open the frontend app in the browser.

Excercise

It's time for an exercise for you. Inside the exercise directory, you will find a small service with Dockerfile. All you need to do is build the image and create yamls to deploy the app on k8s!

Good luck!

Play with MongoDB

# list all pods
kubectl get po

# enter the container 
kubectl exec -it pod-name bash

#--------- inside mongo container

# run mongo shell
mongo

# list all databases
show dbs

# select movies-db database
use movies-db

# add new movie to the collection
db.movies.insert({ title: 'title', genres: 'genres', cast: 'cast', rate: 8, runtime: 120 })

# list all movies
db.movies.find().pretty()