docker-basics

# 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 ```bash # 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。