Docker? Container? Image?

✅ What is Docker?

Docker is a powerful tool that enables applications to run and be managed in isolated environments using container technology. Docker's true value becomes apparent only through direct use and experience. Its greatest advantage is the ability to deploy and run applications without complex environment configurations.

✅ What is a Container?

In Docker, the Container is a core concept. Understanding containers makes learning Docker easy.

A container is similar to a 'mini-computer'. Just as multiple users in Windows can have independent environments, a container establishes an independent virtual environment within a host computer's environment. This allows programs to be installed and run separately in each environment. It's a setup where multiple mini-computer environments can be created within a single host computer, and each of these mini-computers is what Docker calls a Container.

Container Independence: Containers manage the following elements independently:

• Disk (Storage Space): Each container possesses its own storage space and generally cannot directly access files within other containers.
• Network (IP, Port): Each container has a unique network environment and is assigned its own IP address.

✅ What is an Image?

An Image is the 'blueprint' or 'template' used to create a container. One can liken it to a 'game cartridge' for a Nintendo console.

For example, imagine a Node.js-based Express.js server project is turned into an image. When this image is run with Docker, the Express.js server project executes instantly in a container environment, bypassing complex installation processes.

As another example, if a MySQL server is turned into an image, running this image with Docker immediately launches a MySQL server in a container environment, allowing you to use a MySQL database without manual installation.

An Image contains everything needed to run a program (installation steps, configurations, version information, etc.). In essence, through images, we can consistently run applications in identical environments.