ℹ️ Introduction

Containerization has become a cornerstone of modern software development, allowing developers to create, deploy, and run applications reliably across different computing environments. Docker, a leading platform in this space, has gained immense popularity for its simplicity and efficiency. In this guide, you'll learn the basics of Docker, how to set it up, and how to use it to build and deploy applications effortlessly.

What is Docker?

Docker is an open-source platform designed to automate the deployment of applications inside lightweight, portable containers. Containers are standalone, executable packages that include everything needed to run an application code, runtime, libraries, and system tools ensuring consistency across various environments.

Comparing Containers and Virtual Machines

Containers and virtual machines have similar resource isolation and allocation benefits but function differently because containers virtualize the operating system instead of hardware. Containers are more portable and efficient.

CONTAINERS Containers are an abstraction at the app layer that packages code and dependencies together. Multiple containers can run on the same machine and share the OS kernel with other containers, each running as isolated processes in user space. Containers take up less space than VMs (container images are typically tens of MBs in size), can handle more applications and require fewer VMs and Operating systems.

VIRTUAL MACHINES Virtual machines (VMs) are an abstraction of physical hardware turning one server into many servers. The hypervisor allows multiple VMs to run on a single machine. Each VM includes a full copy of an operating system, the application, necessary binaries and libraries – taking up tens of GBs. VMs can also be slow to boot.

Benefits of Using Docker

• Standard: Docker created the industry standard for containers, so they could be portable anywhere
• Consistency Across Environments: Docker ensures that the application behaves the same way on all systems, eliminating the "works on my machine" problem.
• Resource Efficiency: Containers share the host system's kernel and resources, making them more efficient than traditional virtual machines.
• Simplified Deployment: Docker packages applications and their dependencies into a single container, simplifying the deployment process.
• Secure: Applications are safer in containers and Docker provides the strongest default isolation capabilities in the industry

🧠 Key Docker Concepts

Before diving into Docker, it's essential to understand some key concepts:

• Docker Host: refers to the physical or virtual machine where Docker is installed and running. It is responsible for providing the environment in which Docker containers are executed. The Docker Host can be a local machine, a server in the cloud, or any system capable of running Docker. It manages resources like CPU, memory, and storage for containers.
• Docker Daemon: is the background process that runs on the Docker Host and manages Docker objects like containers, images, volumes, and networks. It listens for API requests (through the Docker CLI or other tools) and interacts with the operating system to create and manage Docker containers.
• Docker Images: These are the blueprints for containers. An image contains the application code and all the dependencies it needs to run.
• Docker Containers: A container is a runtime instance of a Docker image. It includes everything required to run the application, isolated from other containers and the host system.
• Docker Registry: A service where Docker images are stored and distributed. Docker Hub is the default public registry where you can find and share images.
• Docker Volumes: These persist data generated and used by Docker containers. Volumes are stored on the host filesystem and are independent of the container's lifecycle, meaning they are not removed when the container is deleted.