Ejibode Ibraheem

Posted on Mar 2

Introduction to Docker: Simplifying Containerized Applications

#devops #aws #docker #cloudcomputing

Table Of Content

Introduction
Basic Docker commands
Running an application using Dockerfile
Docker volume
Docker network
Docker compose file
Clean UP
Conclusion

Prerequisite

An AWS account
A Linux system (Ubuntu 20.04 or Amazon Linux 2 recommended )
Basic knowledge of Linux commands

Introduction
Docker has become an essential tool for building, shipping, and running applications seamlessly across different environments in today's fast-paced software development landscape. Whether you're a developer, DevOps engineer, or system administrator, understanding Docker can significantly enhance your ability to manage applications efficiently.

This article will guide you through key Docker concepts, including:
✅ Dockerfile – Automating image creation
✅ Docker Network – Enabling seamless communication between containers
✅ Docker Volume – Managing persistent data in containers
✅ Docker Compose – Defining and running multi-container applications effortlessly

Each section includes hands-on examples to help you grasp these concepts in a practical way. By the end of this article, you'll be well-equipped to leverage Docker for your containerized workflows. Let's dive in! 🚀

Step 1: launch an EC2 instance

click on Launch instance

Choose your instance name and Amazon Machine Image

Select your instance type and your key pair

Allow traffic from SSH, HTTP, HTTPS and click on launch instance

SSH into the server from your terminal

Step 2: Install Docker

Update and upgrade your system sudo apt-get update -y && sudo apt-get upgrade -y

Install Docker: sudo apt-get install -y docker.io

Enable and start docker : sudo systemctl enable docker && sudo systemctl start docker

Allow the current user to run Docker commands without sudo (optional) sudo usermod -aG docker $USER

Log out and log in again for this change to take effect

Step 3: Explore docker commands

check if docker is running sudo sysetmctl status docker

Pull and run NGINX image from the docker hub docker pull nginx

Verify the downloaded image docker images

Run a container using NGINX image docker run -d -p 8080:80 --name my-nginx nginx

Verify the container is running docker ps

Open your browser and navigate to http://localhost:8080. You should see the Nginx welcome page

Stop the container docker stop my-nginx

Remove the container docker rm my-nginx

Step 4 Create a Custom Docker Image

create a directory
mkdir nginx-image && cd nginx-image
Create a Dockerfile:
vim Dockerfile

Add the following content:

Use the official nginx image as the base image

FROM nginx:latest

Copy a custom HTML file to the nginx document root

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

Create a custom index.html
vim index.html
Add the following content:
<!DOCTYPE html>

My Custom Nginx

Welcome to My Custom Nginx Container!
Build the docker image

docker build -t ejibode .

Run the container using the custom image docker run -d -p 8081:80 --name ejibode ejibode

Open your browser and navigate to http://localhost:8081. You should see your custom HTML content.

Step 5 Manage Volumes

Create a volume: docker volume create my-volume

Run a container and mount the volume docker run -d -p 8082:80 --name my-new-nginx -v my-volume:/usr/share/nginx/html nginx

Access the container shell
docker exec -it my-new-nginx
Add a custom HTML
echo "<h1>Persistent Volume Content</h1>" > /usr/share/nginx/html/index.html

Open your browser and navigate to http://localhost:8082. You should see the updated content.

Stop and remove the container: docker stop my-new-nginx && docker rm my-new-nginx

Step 6: Use docker networks

create a docker network: docker network create my-network

Run a container in the network: docker run -d --name network-nginx --network my-network nginx

Inspect the network docker network inspect my-network

Remove the network docker network rm my-network

Step 7 :Multicontainer Application Using Docker compose

Install Docker compose
sudo apt-get install -y docker-compose
Create a docker-compose.yml file
vim docker-compose.yml
paste the following code

version: '3'
services:
web:
image: nginx
ports:
- "8080:80"
app:
image: custom-nginx
build:
context: .

Run the container
docker-compose up -d
Access the application at http://localhost:8080

Stop and remove the application docker-compose down

Step 8 Clean up

Remove all the stopped containers docker container prune

Remove unused images docker image prune -a

Remove unused volumes docker volume prune

Conclusion
Mastering these concepts enables efficient containerization of applications, improves scalability and streamline deployment processes.
Thank you for reading my article!