🐳 Docker Diaries: Your First Container — Step by Step

Docker Diaries: Your First Container — Let's familiar with docker

Hello again, friends! 👋

In the last blog, we explored the magical world of containers. 🧳

Now it's time to get our hands a little dirty and actually build our very first container using Docker! 🚢

Whether you're a student, a developer, or just curious, this blog is your simple, no-jargon guide to Docker and container creation.

First Things First: What is Docker?

Let’s quickly recap:

Docker is a platform that helps you build, run, and manage containers.

Imagine Docker as a kitchen where you prepare your app (like a meal), pack it (in a box = container), and deliver it anywhere — whether it’s your laptop, server, or the cloud. 🍱

🛠️ Step 1: Install Docker

Before you start, you need Docker installed on your system.

👉 For Windows or Mac:

• Visit: https://www.docker.com/products/docker-desktop

• Download Docker Desktop and follow the installation steps.

👉 For Linux (Ubuntu):

bash
sudo apt update
sudo apt install docker.io
sudo systemctl start docker
sudo systemctl enable docker

To confirm Docker is installed, run:

bash
docker --version

You should see something like:

Docker version 28.0.4, build b8034c0

✅ You’re ready to go now!

✍️ Step 2: Write Your First Dockerfile

Let’s containerize a simple app.
We’ll start with a basic Python app that prints “Hello from Docker!”.

🗂 Create a project folder:

mkdir docker-demo

cd docker-demo

📝 Inside that folder, create a file called app.py:

print("Namaste! from Docker!")

📦 Now, create a file named Dockerfile (no file extension):

Dockerfile
# Use an official Python base image
FROM python:3.10

# Set the working directory inside the container
WORKDIR /app

# Copy current files to the container
COPY . .

# Command to run when the container starts
CMD ["python", "app.py"]

Step 3: Build Your Docker Image

A Docker image is like a blueprint of your application.

Run this in your terminal (inside the docker-demo folder):

bash
docker build -t my-first-container .

What’s happening?

• -t gives it a tag (name).

• . tells Docker to use the current directory.

After a few seconds, your image will be ready! Congrats🎉

Step 4: Run Your Container

Let’s see the magic!

bash
docker run my-first-container

You should see this output:

csharp
Hello from Docker!

🥳 Congrats! You just created and ran your first Docker container!

🧽 Step 5: Clean Up (Best Practice!)

As you work with Docker, your system can fill up with unused containers and images.

Here are a few handy clean-up commands:

• List all containers:

  bash
  docker ps -a
  

• Remove a container:

  bash
  docker rm <container_id>
  

• Remove an image:

  bash
  docker rmi <image_id>
  

• Remove all stopped containers and unused images:

  bash
  docker system prune
  

💡 Tip: Always clean up regularly to save space and avoid confusion.

---

✅ Best Practices for Docker Beginners

1. Keep Dockerfiles simple – Avoid unnecessary layers.

2. Use .dockerignore – Like .gitignore, to avoid copying unwanted files.

3. Pin your base image versions – Example: python:3.10, not just python.

4. Don’t run as root inside containers – It’s safer to create a user.

5. Keep your images small – Clean up unnecessary files during build.

What’s Next?

Now that you’ve built your first container, you’re ready to explore:

• Docker Compose (to manage multi-container apps)

• Docker Hub (to share your containers)

• And eventually, Kubernetes (to manage lots of containers!)

 So,

Learning Docker is like learning to pack smart — it makes your apps organized, portable, and ready to travel. ✈️

Try this out and let me know how your first Docker experience goes!
If you’re stuck or curious, just drop a comment. I’ve got your back. 💪