1. Introduction

1.1 Brief Explanation of the Tutorial's Goal

In this tutorial, we aim to provide a comprehensive understanding of Docker and its purpose in modern web development. Docker is a powerful tool that allows developers to create, deploy, and run applications using containers, thus enhancing the efficiency and effectiveness of the software development process.

1.2 What Will the User Learn

After completing this tutorial, the user will be able to:
- Understand what Docker is and why it is important
- Set up Docker on their local system
- Create and manage Docker containers
- Understand the role of Docker in the software development lifecycle

1.3 Prerequisites

The user should have a basic understanding of Linux commands and software development principles. Familiarity with the concept of virtualization would be beneficial but is not mandatory.

2. Step-by-Step Guide

2.1 What is Docker?

Docker is a platform that uses OS-level virtualization to deliver software in packages called containers. Containers are isolated from each other and bundle their own software, libraries, and configuration files; they can communicate with each other through well-defined channels.

2.2 Docker Installation

Docker can be installed on various platforms such as Windows, MacOS, and Linux. For instance, on a Ubuntu system, you can install Docker with the following commands:

sudo apt-get update
sudo apt-get install docker-ce

Remember to check the Docker documentation for platform-specific installation guidelines.

2.3 Docker Containers

Docker containers are the running instances of Docker images. You can create, start, stop, move, or delete a container using the Docker API or CLI. They are lightweight, standalone, and executable packages that include everything needed to run a piece of software.

3. Code Examples

3.1 Running a Docker Container

Here we'll fetch and run the hello-world Docker image.

docker run hello-world

This command will download the hello-world image if it's not already present, and run it in a new container. You'll see a welcome message explaining that your installation appears to be working correctly.

3.2 Creating a Dockerfile

A Dockerfile is a script containing various commands that will be executed in order to build a Docker image.

# Use an official Python runtime as a parent image
FROM python:3.7-slim

# Set the working directory in the container to /app
WORKDIR /app

# Copy the current directory contents into the container at /app
ADD . /app

# Install any needed packages specified in requirements.txt
RUN pip install --trusted-host pypi.python.org -r requirements.txt

# Make port 80 available to the world outside this container
EXPOSE 80

# Run app.py when the container launches
CMD ["python", "app.py"]

This Dockerfile describes an image that contains a Python application which listens on port 80.

4. Summary

In this tutorial, we have learned about Docker, its installation process, and its role in creating and managing containers. We also looked at some basic Docker commands and Dockerfile creation.

5. Practice Exercises

5.1 Exercise 1: Install Docker on Your Machine

Follow the Docker installation guide for your specific OS and install Docker.

5.2 Exercise 2: Run a Docker Container

Fetch and run the hello-world Docker image, as shown in the example code.

5.3 Exercise 3: Create Your Own Dockerfile

Following the example given, create your own Dockerfile for a simple Python or Node.js application. Build and run the Docker image.

Remember, the best way to learn is through practice. So, keep experimenting with different Docker commands and functionalities. Good luck!