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Docker Introduction

Docker is an open-source platform for developing, deploying, and running applications. Through container technology, developers can create consistent, portable, and scalable application environments, improving development efficiency and application reliability.

note

In some regions, pulling Docker images from public registries may be restricted due to network limitations. In such cases, the examples in this tutorial are intended for demonstration and learning purposes.

1. Containers​

A Docker container is a lightweight, independent, executable software package that contains everything needed to run an application, including:

  • Application code
  • Runtime
  • System tools
  • System libraries
  • Configuration settings

Container Features​

Feature Description

Lightweight Containers share the kernel of the host operating system

Independence Containers are isolated with their own filesystem, processes, and networking

Portability Containers can run on any platform that supports Docker​

warning

Docker containers are built on top of the host operating system and CPU architecture. Containers built for one architecture may not run on another.

2. Images​

A Docker image is a read-only template used to create containers.

Image Features​

Feature Description

Immutability Images are read-only once created

Layered Images are composed of multiple layers representing Structure build steps​

note

If you modify data inside a running container, those changes are not saved back to the image unless you explicitly create a new image from the container.

3. Docker Engine​

The Docker Engine is a client--server application consisting of:

  • Docker Daemon\
  • REST API\
  • Command Line Interface (CLI)

3.1 Docker Daemon​

The Docker Daemon is responsible for:

  • Building images\
  • Running containers\
  • Managing container lifecycle

3.2 Docker CLI​

The Docker CLI provides command-line tools to:

  • Build images\
  • Run containers\
  • Manage Docker resources

4. Docker Hub​

Docker Hub is a public cloud registry used to store and distribute Docker images.

5. Main Advantages of Docker​

Advantage Description

Consistency Same environment across development and production

Isolation Improved security and stability

Portability Easy migration across platforms

Efficiency Lighter than virtual machines​

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