Installation

This section guides you through installing Docker on various operating systems. We’ll focus on Ubuntu Linux, but here are links for Windows and macOS installations.

Linux (Ubuntu)

These instructions are specifically for Ubuntu. For other Linux distributions, refer to the official Docker documentation: Install Docker Engine.

Steps:

  1. Set up Docker’s apt repository: This allows your system to download and install official Docker packages.

    # Update the apt package index and install packages to allow apt to use a repository over HTTPS:
sudo apt-get update
sudo apt-get install -y ca-certificates curl gnupg

# Create a directory for the keyring (if it doesn't exist)
sudo install -m 0755 -d /etc/apt/keyrings

# Download Docker's official GPG key and add it to the keyring:
curl -fsSL [https://download.docker.com/linux/ubuntu/gpg](https://download.docker.com/linux/ubuntu/gpg) | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Set permissions on the key file
sudo chmod a+r /etc/apt/keyrings/docker.gpg

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

# Update the apt package index again:
sudo apt-get update

    Explanation:

    • apt-get update: Updates the local package index.
    • apt-get install -y ca-certificates curl gnupg: Installs required packages (-y automatically answers “yes” to prompts).
    • install -m 0755 -d /etc/apt/keyrings: Creates the /etc/apt/keyrings directory with correct permissions.
    • curl ... | sudo gpg --dearmor ...: Downloads Docker’s GPG key, dearmors it (converts it to a binary format), and saves it.
    • chmod a+r ...: Sets read permissions on the key file.
    • echo ... | sudo tee ...: Adds the Docker repository to your system’s list of software sources.
    • $(lsb_release -cs): gets your ubuntu version’s codename.

  2. Install Docker Engine:

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

    Explanation: *Installs packages for docker.

  3. Verify Installation:

    docker --version

# This is the first program people run to ensure that docker is properly installed
sudo docker run hello-world

    Sample Output (truncated):

    Docker version ##.#.#, build ######
    
...

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
...
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.
...

    This command downloads a test image (“hello-world”) and runs it in a container. If you see the “Hello from Docker!” message, your installation is working.

  4. (Optional, but Recommended) Manage Docker as a Non-Root User:

    By default, you need to use sudo to run Docker commands. To avoid this, add your user to the docker group:

    sudo usermod -aG docker $USER

    Important: You’ll need to log out and log back in (or run newgrp docker) for this change to take effect. After logging back in, you should be able to run docker commands without sudo.

    Refer to the official Docker documentation for more details on post-installation steps for Linux: Linux Post-Installation