robindeclerck/shippingchallenge repository overview

⁠Linux Shipping Challenge

⁠Assignment

• Create your own kubernetes stack with 1 worker
• Containerized application on worker
  • When surname changes in DB, webpage changes automatically
  • When layout of webpage changes, the worker will display the new layout automatically
  • Use the webstack which is assigned to you

⁠My assigned webstack

⁠Points

10/20 - stack in Docker
14/20 - mk8s cluster with 1 worker

• Vagrant
• Extra worker
• Management webplatform for containers:

• Something else than MK8s with the same purpose
• (A practical linux joke for docents / a linux koan to enlighten your docents = extra point)

⁠Installation

⁠Create the Python project

I used the Python package web.py⁠ to create my Python application. I tried to use Flask but Lighttpd's support for Python is old and caused a lot of problems when trying to host the application.

In the Python application I created a return with "Hi {firstname}' with 'firstname' coming from the database.

Database connection function:

def setup_database_connection():
    # CONNECTION TO SQL SERVER #
    import mysql.connector

    mydb = mysql.connector.connect(
        user=DATABASE_USER,
        passwd=DATABASE_PASSWORD,

        host=DATABASE_HOST,
        port=DATABASE_PORT,

        database=DATABASE_DB,
    )
    return mydb

To get the data out of the database:

# DB Connection
database = setup_database_connection()
cursor = database.cursor()

db_query = 'SELECT surname FROM User WHERE userId = 1'
cursor.execute(db_query)

surname = cursor.fetchone()[0]

⁠Dockerfile

The dockerfile is needed to build and run the application inside a container.

In the dockerfile I write all needed dependencies that need to be installed.

FROM ubuntu:18.04

RUN apt-get update
RUN apt-get -y install lighttpd
RUN apt-get install -y python3-pip python3-dev

ENV LIGHTTPD_VERSION=1.4.55-r1

RUN apt-get install lighttpd -y

COPY ./etc/lighttpd/* /etc/lighttpd/


EXPOSE 80

WORKDIR /var/www/shippingchallenge

COPY ./requirements.txt ./

RUN pip3 install --no-cache-dir -r requirements.txt

COPY ./ .

CMD ["lighttpd","-D","-f","/etc/lighttpd/lighttpd.conf"]

Main steps:

• Start Ubuntu and update
• Install Lighttpd
• Expose port 80 (this is the port inside the docker container that will be exposed)
• Install my application
• Install the dependencies in requirements.txt
• State the start command

⁠Docker Hub

I put the project online so I (and Kubernetes) can download the project on any machine via: robindeclerck/shippingchallenge

When I push a new version to GitHub, Docker Hub wil automatically create a new version via automated builds.

⁠Kubernetes

Deployment
This will download the image from Docker Hub robindeclerck/shippingchallenge and create 3 pods.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: shippingchallenge-deployment
  namespace: default
spec:
  replicas: 3
  selector:
    matchLabels:
      app: lighttpd
  template:
    metadata:
      labels:
        app: lighttpd
    spec:
      containers:
        - name: lighttpd
          image: robindeclerck/shippingchallenge
          ports:
            - containerPort: 80
              name: http

Service
The service needs to attach the deployment via selector, app.

apiVersion: v1
kind: Service
metadata:
  name: shippingchallenge-service
  namespace: default
spec:
  type: ClusterIP
  ports:
    - port: 80
  selector:
    app: lighttpd

Ingress
The Ingress needs to specify the service that needs to be used for the port via 'serviceName'

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: shippingchallenge-ingress
  namespace: default
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
  rules:
    - host: shippingchallenge.local
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              serviceName: shippingchallenge-service
              servicePort: 80

You also need to specify 'shippingchallenge.local' in your hosts file:
sudo nano /etc/hosts and add the ip of the ingress and the host (shippingchallenge.local).

If you just go to the IP of the application you will get a "NGINX ERROR NOT FOUND".

⁠Ubuntu

I installed the latest Ubuntu 20.10⁠ on my VirtualBox.
Note: Using default 10GB space is not enough for this project

Install Curl: sudo apt-get install curl

Install Docker:
https://docs.docker.com/engine/install/ubuntu/⁠

I had a problem where docker did not have permissions to execute containers I found the fix on stackoverflow (using docker with sudo != ok):
https://stackoverflow.com/questions/48957195/how-to-fix-docker-got-permission-denied-issue⁠

Install Kubernetes:
https://kubernetes.io/docs/tasks/tools/install-kubectl/⁠

Install Minikube (needed for ingress-controller):
https://v1-18.docs.kubernetes.io/docs/tasks/tools/install-minikube/⁠

Start Minikube to install itself:
minikube start

For the Ingress we need an Ingress controller, otherwise there will no IP be added to the Ingress:
minikube addons enable ingress

So the Ingress will get an 'ADDRESS'

After the installation I started the application (the Deployment, Service, Ingress are all in the same file seperated with ---):
kubectl apply -f deploy.yaml

The project will install and run after this command. This command is also used when changing the deploy.yaml file

⁠Kubernetes dashboard

Install Kubernetes dashboard: https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/⁠

You will need a user and token for the dashboard: https://github.com/kubernetes/dashboard/blob/master/docs/user/access-control/creating-sample-user.md⁠

You can access Dashboard using the kubectl command-line tool by running the following command:
kubectl proxy

To go to the dashboard:
http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/#/discovery?namespace=default⁠

⁠Debugging

It's possible to debug a kubernetes deployment:
kubectl get pods

kubectl exec -it shippingchallenge-deployment-79998c989c-6jvvq sh

I used this to check if my service/deployment worked by installing curl and using curl shippingchallenge-service to check if my application was running correctly inside Kubernetes

This is also really handy to check your database deployment:

⁠Change database row

Login:
$ mysql -u user -p'password'
Show databases:
mysql> SHOW DATABASES;
Insert new row:
mysql> USE ShippingChallenge;
mysql> SELECT * FROM User;
mysql> UPDATE User SET surname = "Bob" WHERE userId = 1;

⁠To restart a deployment (will also update the image):

kubectl get deployment
kubectl rollout restart deployment [deployment_name]