Docker Tutorial

Docker is an open-source application container engine, based onGo Languageand open-sourced under the Apache 2.0 license.

Docker allows developers to package their applications and dependencies into a lightweight, portable container, which can then be published to any popular Linux machine, and it also enables virtualization.

Containers fully use a sandbox mechanism, with no interfaces between each other (similar to iPhone apps); more importantly, containers have extremely low performance overhead.

After version 17.03, Docker is divided into CE (Community Edition) and EE (Enterprise Edition). We can just use the Community Edition.

Who should read this tutorial?

This tutorial is suitable for operations engineers and backend developers. Through this tutorial, you can learn how to use Docker step by step.

What you need to know before reading this tutorial

Before reading this tutorial, you need to master common Linux commands. You can use this site'sLinux TutorialLearn the related commands.

Docker application scenarios

Microservices architecture:Each service is independently containerized, making it easy to manage and scale.
CI/CD pipeline:Integrates with Jenkins/GitLab CI to achieve automated builds and testing.
Standardization of development environments:New members can start all dependent services (such as databases, message queues) in one click.
Cloud-native fundamentals:Orchestration tools such as Kubernetes manage container clusters based on Docker.

Core Advantages

Cross-platform consistency:Solves the "it works on my machine" problem, ensuring consistency across development, testing, and production environments.
Resource Efficiency:Containers directly share the host kernel, without virtualizing the entire operating system, saving memory and CPU.
Fast Deployment:Containers start in seconds, supporting automated scaling and shrinking.
Isolation:Each container has its own independent file system, network, and process space.

Core Concepts

Container:Lightweight runtime instances, containing application code, runtime environment, and dependency libraries. Created from images, isolated from other containers, sharing the host operating system kernel (more efficient than virtual machines).
Image:Read-only templates that define the container's runtime environment (such as operating system, software configuration, etc.). Optimize space and build speed through layered storage (Layer).
Dockerfile：A text file that describes how to automatically build images (for example, specifying a base image, installing software, copying files, etc.).
Registry:A platform for storing and distributing images, such as Docker Hub (official public repository) or private repositories (e.g., Harbor).

Basic Commands

Example

# Pull the image (e.g., official Nginx image)
docker pull nginx

# Run the container (-d run in background, -p map ports)
docker run -d -p 80:80 nginx

# List running containers
docker ps

# Build the image (based on the Dockerfile in the current directory)
docker build -t my-app .

# Enter the container
docker exec -it <Container ID> /bin/bash