Introduction to Docker for Beginners
Prerequisites
Before you begin, ensure that you have Docker installed on your machine. Follow the official Docker installation guide for your operating system.
Understanding Containers and Images
What are Containers?
A container is a lightweight, standalone, and executable software package that includes everything needed to run a piece of software, including the code, runtime, libraries, and system tools.
What are Images?
An image is a lightweight, standalone, and executable software package that includes everything needed to run a container. It serves as the blueprint for containers.
Basic Docker Commands
1. Verify Docker Installation
To ensure Docker is installed, run:
docker --version
2. Run Your First Container
Run a simple container:
docker run hello-world
3. List Running Containers
View the containers that are currently running:
docker ps
4. Explore Docker Images
List the Docker images on your machine:
docker images
Building and Running Custom Containers
1. Create a Dockerfile
Create a file named Dockerfile in your project directory:
# Use an official Ubuntu runtime as a parent image
FROM ubuntu:20.04
# Set the working directory
WORKDIR /app
# Copy the current directory contents into the container at /app
COPY . /app
# Install any needed packages specified in requirements.txt
RUN apt-get update && apt-get install -y python3
# Make port 80 available to the world outside this container
EXPOSE 80
# Define environment variable
ENV NAME World
# Run app.py when the container launches
CMD ["python3", "app.py"]
2. Build the Docker Image
Build the Docker image using the Dockerfile:
docker build -t my-python-app .
3. Run the Custom Container
Run the container from the built image:
docker run -p 4000:80 my-python-app
Visit http://localhost:4000 to see your Python application running in a Docker container.
Conclusion
Congratulations! You’ve taken your first steps into the world of Docker. This tutorial covered the basics of containers, images, and running custom applications in Docker containers. Dive deeper into Docker’s features and explore its vast ecosystem for more advanced use cases.