Kubernetes In Action

Mastering Deployments In A Flash

Learning Outcome

5

Prepare the application for Kubernetes deployment

4

Push the image to Docker Hub

3

Build a Docker image

2

Containerize an application using Docker

Explain what a Dockerfile is

1

Create a simple web application

 Analogy

Imagine you have built a food recipe

Before selling it in restaurants you must

 Prepare the recipe

 Pack it properly

Send it to different restaurants

 Similarly in software

Create Application → Package with Docker → Upload to Docker Hub → Deploy on Kubernetes

Creating a Simple Web Application

First, we create a basic web application

For learning purposes, we create a simple HTML page

Example file:

index.html

<!DOCTYPE html>
<html>
<head>
<title>My Web App</title>
</head>
<body>
<h1>Hello from Kubernetes </h1>
<p>This is my first containerized application.</p>
</body>
</html>

Steps:

Create a project folder

mkdir my-web-app
cd my-web-app

Create the HTML file

touch index.html

 Add your web page content

<!DOCTYPE html>
<html>
<head>
<title>My Web App</title>
</head>
<body>
<h1>Hello from Kubernetes </h1>
<p>This is my first containerized application.</p>
</body>
</html>

This simple page will be served using a web server container

Containerizing the Application with Docker

we package the application using Docker

To do this we create a Dockerfile

A Dockerfile tells Docker how to build the container image

Create a file named

Dockerfile

Example Dockerfile:

FROM nginx:latest
COPY index.html /usr/share/nginx/html

Explanation:

FROM nginx:latest

Uses the Nginx web server image

COPY index.html /usr/share/nginx/html

Copies our web page into the Nginx server folder

Building the Docker Image

Now we build the Docker image from the Dockerfile

Command:

docker build -t my-web-app

Explanation:

docker build → builds the image

-t → assigns a tag/name to the image

. → tells Docker to use the current folder

After building, check the image:

docker images

You should see:

my-web-app

This image contains:

Application + Web Server + Dependencies

Testing the Docker Container

Before pushing the image, we test it locally

Run the container:

docker run -d -p 8080:80 my-web-app

Explanation:

-d → runs container in background

-p 8080:80 → maps port 8080 to container port 80

Open browser:

http://localhost:8080

You should see your web application running

Creating a Docker Hub Account

Before pushing images, we need a Docker Hub account

Steps:

Go to Docker Hub website

Create an account

Login from terminal docker login

Enter:

Docker Hub username

Password

Now your system is connected to Docker Hub registry

Tagging the Docker Image

Before pushing, we must tag the image with Docker Hub username

Command:

docker tag my-web-app username/my-web-app

Example:

docker tag my-web-app john/my-web-app

Explanation:

username → your Docker Hub username

my-web-app → repository name

This prepares the image for uploading

Pushing the Image to Docker Hub

Now we upload the image to Docker Hub

Command:

docker push username/my-web-app

Example:

docker push john/my-web-app

Docker will:

 Upload image layers

Store them in Docker Hub

Make the image accessible from anywhere

Now the image is available online

Why We Push Images to Docker Hub

Docker Hub acts as a central image repository

Benefits:

Store container images

Share images with teams

Deploy images on servers

Use images in Kubernetes

Kubernetes will later pull this image from Docker Hub to run containers

Workflow:

Deployment Preparation for Kubernetes

Now our application is ready for deployment

We have:

Created a web application

Containerized it with Docker

Built a Docker image

Tested the container

Pushed the image to Docker Hub

Next step in Kubernetes:

Create a Deployment YAML file

This file will tell Kubernetes

Which image to run

How many replicas to create

How to manage the application

Summary

4

Tagging Docker images , Pushing images to Docker Hub

3

Writing a Dockerfile , Building Docker images ,Testing containers locally

2

Containerizing applications using Docker

1

Creating a simple web application

Quiz

Which command is used to upload a Docker image to Docker Hub?

A. docker build

B. docker run

C. docker push

D. docker create

Quiz-Answer

Which command is used to upload a Docker image to Docker Hub?

A. docker build

B. docker run

C. docker push

D. docker create