Why Should You Use Docker?

Docker brings many benefits to developers and teams:

• Consistency → No more environment mismatch issues

• Efficiency → Save system resources compared to VMs

• Portability → Deploy the same app across multiple platforms

• Scalability → Easily run multiple containers for microservices

• Integration → Works seamlessly with modern CI/CD pipelines

Here is a diagram showing the difference between Docker and virtual machines.

Installing Docker

Docker provides installation packages for Windows, Linux, and macOS. Let’s go through them:

1. Windows

• Download Docker Desktop for Windows from Docker’s official site.

• Install it like a regular application.

• Ensure WSL 2 is enabled (Windows Subsystem for Linux 2).

• After installation, open PowerShell or Command Prompt and test with:

docker --version

2. macOS

• Download Docker Desktop for Mac from the same official page.

• Install and launch the app.

• Verify installation:

docker --version

3. Linux

(a) Ubuntu/Debian

sudo apt-get update
sudo apt-get install ca-certificates curl gnupg lsb-release

# Add Docker’s official GPG key
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Setup repo and install
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Check version:

docker --version

(b) RHEL / CentOS

# Remove old versions
sudo yum remove docker \
                docker-client \
                docker-client-latest \
                docker-common \
                docker-latest \
                docker-latest-logrotate \
                docker-logrotate \
                docker-engine

# Setup repository
sudo yum install -y yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

# Install Docker
sudo yum install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Start and enable service
sudo systemctl start docker
sudo systemctl enable docker

Check version:

docker --version

Post-Installation Setup (Linux Only)

By default, you’ll need sudo to run Docker commands. To avoid typing sudo every time, add your user to the docker group:

sudo usermod -aG docker $USER

Then log out and log back in (or restart your system). Verify by running:

docker run hello-world

If it works without sudo, the setup is complete.

Running Your First Container

Now that Docker is installed, let’s test it by running a simple container:

docker run hello-world

What happens here?

1. Docker checks if the hello-world image exists locally.

2. If not, it pulls it from Docker Hub (a public registry of images).

3. A new container runs and prints a welcome message.

Congratulations 🎉 — you’ve successfully set up Docker and launched your first container!

Key Terms to Remember

• Image → The blueprint for your container.

• Container → A running instance of an image.

• Docker Hub → A registry of pre-built images.

• Dockerfile → Instructions for building custom images.

What’s Next?

In the next article, we’ll dive deeper into Docker basics: exploring images, containers, and registries in detail.

Stay tuned for Part 2: Understanding Images, Containers, and Registries in Docker.