Docker Basics — 概念与基础

Docker 生态的第一入口。从零理解 Docker 概念、架构和基础操作。

When to Use

✅ Use When	❌ Skip When
New to Docker, learning from scratch	Already proficient with Docker
Need to understand container vs VM	Need specific Dockerfile/CLI commands → docker-build / docker-run
Setting up Docker for the first time	Need multi-container orchestration → docker-compose
Evaluating whether to adopt Docker	Need security scanning → docker-security

Core Concepts

Concept	Definition	Analogy
Image	Read-only template with app + dependencies	Class definition
Container	Runnable instance of an image	Object instance
Registry	Repository for storing/sharing images	App Store
Docker Engine	Runtime that builds and runs containers	JVM / Python interpreter

Container vs VM

Aspect	Container	VM
Isolation	Process-level (share host kernel)	Hardware-level (full OS)
Startup	Seconds	Minutes
Size	MB	GB
Density	Dozens per host	Few per host
Use Case	Microservices, CI/CD, dev environments	Legacy apps, multi-OS, strong isolation

Docker Architecture

┌─────────────────────────────┐
│         Docker CLI           │  ← docker build/run/push...
├─────────────────────────────┤
│       Docker Daemon          │  ← dockerd: manages images, containers, networks, volumes
├─────────────────────────────┤
│       containerd             │  ← container runtime supervisor
├─────────────────────────────┤
│        runc                  │  ← OCI runtime (actually runs containers)
└─────────────────────────────┘
         │
    ┌────┴────┐
    ▼         ▼
 Registry   Host OS
 (Docker    (Linux kernel:
  Hub)       namespaces, cgroups)

Quick Start

# Verify installation
docker --version
docker run hello-world

# Pull and run your first container
docker pull nginx:alpine
docker run -d -p 8080:80 --name my-nginx nginx:alpine

# Check it's running
curl localhost:8080
docker ps
docker stop my-nginx

Docker Object Model

docker run → Container (running instance of an image)
docker build → Image (built from Dockerfile)
docker pull → Image (downloaded from Registry)
docker push → Image (uploaded to Registry)
docker volume → Volume (persistent data)
docker network → Network (container communication)

Installation Path

OS	Method	Notes
macOS	Docker Desktop	Includes GUI, CLI, Compose, K8s
Windows	Docker Desktop + WSL2	WSL2 backend recommended
Linux	apt/yum install docker-ce	No GUI; add user to docker group
CI/Server	Docker Engine only	Minimal footprint

Key CLI Groups

docker container   → create, run, start, stop, rm, ls, inspect, logs, exec
docker image       → build, pull, push, tag, ls, rm, prune, inspect
docker volume      → create, ls, rm, prune, inspect
docker network     → create, ls, rm, inspect, connect, disconnect
docker system      → df, prune, info, events

Workflow — 推荐学习路径

Step 1: 理解概念: 阅读 Core Concepts（Image/Container/Registry/Engine） Step 2: 安装验证: docker run hello-world 确认安装成功 Step 3: 第一个容器: docker run -d -p 8080:80 nginx:alpine 体验 Step 4: 进阶学习: 掌握 docker build（写 Dockerfile）→ docker run（管理容器） Step 5: 进入生态: 按需探索 docker-dockerfile/docker-build/docker-compose

Gotchas — Common Pitfalls

• Image vs Container confusion: docker run creates a NEW container each time. → Recovery: Use docker start <name> to restart an existing container; docker ps -a to see stopped containers.
• Root permission: Linux requires sudo unless user is added to docker group (security risk: docker group = root access). → Recovery: sudo usermod -aG docker $USER && newgrp docker or use rootless Docker.
• Disk bloat: Old images/volumes/cache accumulate fast. → Recovery: docker system prune -a monthly; check with docker system df first.
• Port conflict: -p 8080:80 means host:8080 → container:80. If host port is taken, change host side. → Recovery: lsof -i :8080 to find process occupying the port, then use a different port.
• Data loss: Without volumes, container data is ephemeral. → Recovery: Always use -v volume_name:/data for stateful data; never rely on container filesystem.

Boundary — 能力边界（适用与不适用场景）

分类	场景	说明
✅ 能做	Docker 概念教学（Image/Container/Registry/Engine）	从零解释核心概念
✅ 能做	安装指导（macOS/Linux/Windows）	提供各平台安装步骤
✅ 能做	第一个容器实操	docker run hello-world + nginx 示例
⚠️ 需条件	深入理解容器原理	建议结合 Linux namespace/cgroups 文档
⚠️ 需条件	Docker Compose 多容器	基础概念后进入 docker-compose 技能
❌ 超范围	编写 Dockerfile	使用 docker-dockerfile
❌ 超范围	构建/推送镜像	使用 docker-build
❌ 超范围	生产部署/Swarm/K8s	使用 docker-production

When NOT to Use This Skill

❌ Skip	✅ Use Instead
Need to write Dockerfile	docker-build
Need container management	docker-run
Need multi-container apps	docker-compose
Already know Docker basics	Jump to specific skill

Security & Stability

• All examples are educational. Use official images and verified publishers in production.
• Docker group membership on Linux is equivalent to root access.
• No executable scripts bundled. This skill teaches concepts and basic operations.

📚 官方文档参考

文档	地址
Docker 概述	https://docs.docker.com/get-started/docker-overview/
Docker 概念	https://docs.docker.com/get-started/docker-concepts/the-basics/what-is-a-container/
安装 Docker	https://docs.docker.com/get-started/get-docker/
Docker 引擎	https://docs.docker.com/engine/
Docker 入门 workshop	https://docs.docker.com/get-started/workshop/
Docker CLI 参考	https://docs.docker.com/reference/cli/docker/

🧭 Docker Skills Journey

📍 You are here: docker-basics — Step 1: Docker 概念与基础

basics → build → run → networking/storage → compose → security/cicd → production/troubleshooting → ai-ml

→ Next: docker-build — Write Dockerfiles and build optimized images

FAQ

Q1: 如何快速上手此技能？ A: 参考上方的快速开始章节，按步骤操作即可。

Q2: 遇到版本不兼容问题怎么办？ A: 检查依赖版本，使用 lock 文件锁定，参考常见陷阱章节。

Q3: 如何在生产环境使用？ A: 参考最佳实践章节，确保配置正确，做好监控和日志。

Q4: 性能如何优化？ A: 参考性能优化相关文档，使用缓存、索引等手段。

Q5: 如何贡献或反馈问题？ A: 在 GitHub 仓库提交 Issue 或 Pull Request。

Q6: 是否支持中文？ A: 支持中文文档和中文注释，详见国内适配章节。