Docker - Cloud: A Beginner's Guide to Cloud Computing with Docker

Hello there, future cloud computing wizards! I'm thrilled to be your guide on this exciting journey into the world of Docker and cloud computing. As someone who's been teaching computer science for over a decade, I've seen countless students light up with excitement when they grasp these concepts. So, let's dive in and demystify Docker and cloud computing together!

Docker - Cloud

Getting Started

Before we sail into the cloud, let's start with the basics. Docker is like a magical shipping container for your software. It packages up your application and all its dependencies into a standardized unit called a container. This makes it super easy to move your application from one environment to another, just like how shipping containers can be easily transferred between ships, trucks, and trains.

What is Docker?

Docker is an open-source platform that automates the deployment, scaling, and management of applications. It uses containerization technology to wrap up an application in a complete filesystem that contains everything it needs to run: code, runtime, system tools, system libraries – anything you can install on a server.

Let's look at a simple example of a Dockerfile, which is like a recipe for creating a Docker container:

FROM python:3.9-slim
WORKDIR /app
COPY . /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

This Dockerfile does the following:

Starts with a base image of Python 3.9
Sets the working directory to /app
Copies our application files into the container
Installs our Python dependencies
Specifies the command to run our application

What is Cloud Computing?

Now, imagine you could rent a super-powerful computer that's always on and accessible from anywhere in the world. That's essentially what cloud computing offers! It's like having a virtual computer in the sky that you can access whenever you need it.

Connecting to the Cloud Provider

To start our cloud adventure, we need to choose a cloud provider. The big three in the industry are Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). For this tutorial, let's use AWS as our example.

Setting Up an AWS Account

Go to the AWS website and sign up for an account.
Once you're in, you'll see the AWS Management Console. It might look overwhelming at first, but don't worry – we'll focus on what we need.

Installing the AWS CLI

The AWS Command Line Interface (CLI) is like a magic wand that lets you control AWS services from your terminal. Let's install it:

pip install awscli
aws configure

When you run aws configure, you'll be asked for your AWS Access Key ID and Secret Access Key. These are like your username and password for AWS services.

Setting Up Nodes

In the world of Docker and cloud computing, a "node" is essentially a machine (virtual or physical) that can run Docker containers. Let's set up a node on AWS using a service called EC2 (Elastic Compute Cloud).

Creating an EC2 Instance

In the AWS Management Console, navigate to EC2.
Click "Launch Instance".
Choose an Amazon Machine Image (AMI) - let's pick Amazon Linux 2.
Select an instance type (t2.micro is free tier eligible).
Configure instance details, add storage, and tags as needed.
Configure a security group to allow SSH access.
Review and launch the instance.

Now you have a virtual machine in the cloud! Let's connect to it:

ssh -i your-key-pair.pem ec2-user@your-instance-public-dns

Installing Docker on the Node

Once you're connected to your EC2 instance, let's install Docker:

sudo yum update -y
sudo amazon-linux-extras install docker
sudo service docker start
sudo usermod -a -G docker ec2-user

Congratulations! You now have a Docker-ready node in the cloud.

Deploying a Service

Now for the exciting part - let's deploy a simple web application to our cloud node using Docker!

Creating a Simple Web App

First, let's create a simple Python web app. Create a file called app.py:

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, Docker Cloud World!'

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=80)

Dockerizing the App

Now, let's create a Dockerfile to containerize our app:

FROM python:3.9-slim
WORKDIR /app
COPY . /app
RUN pip install flask
EXPOSE 80
CMD ["python", "app.py"]

Deploying to the Cloud Node

Build the Docker image:
```
docker build -t my-cloud-app .
```
Run the container:
```
docker run -d -p 80:80 my-cloud-app
```
Your app is now running! You can access it by visiting your EC2 instance's public IP address in a web browser.

Conclusion

Wow, what a journey! We've gone from zero to hero, deploying a containerized application in the cloud. Remember, this is just the tip of the iceberg. The world of Docker and cloud computing is vast and exciting, with endless possibilities to explore.

Here's a quick reference table of the main Docker commands we've used:

Command	Description
`docker build`	Builds a Docker image from a Dockerfile
`docker run`	Runs a Docker container
`docker ps`	Lists running containers
`docker stop`	Stops a running container
`docker rm`	Removes a container

Keep practicing, keep exploring, and before you know it, you'll be orchestrating complex cloud infrastructures like a seasoned pro. Remember, every expert was once a beginner. Happy clouding!

Credits: Image by storyset