What is docker-helper?

The Docker Helper skill is a comprehensive guide designed to streamline containerization workflows for developers. It provides expert assistance in writing optimized Dockerfiles, configuring multi-service environments with docker-compose, and implementing industry-standard best practices. By focusing on multi-stage builds, image size reduction, and security hardening, this skill helps teams build faster, smaller, and more secure containers for production and development environments.

When should I use docker-helper?

docker-helper is useful in the following scenarios: • Generating optimized, production-ready Dockerfiles using multi-stage builds to significantly reduce image size and attack surface. • Orchestrating complex microservices architectures with docker-compose to ensure consistent development, testing, and staging environments. • Troubleshooting and debugging containerized applications through advanced logging, shell access, and build-process analysis. • Implementing security best practices such as non-root user configurations, .dockerignore optimization, and vulnerability scanning. • Migrating legacy applications to containerized environments by providing structured templates and step-by-step configuration guidance.

name	docker-helper
description	Docker容器化开发指南。当用户需要编写 Dockerfile、配置 docker-compose、优化镜像大小、调试容器问题或实施容器化最佳实践时使用此技能。

Docker Helper

帮助开发者高效地进行容器化开发，编写优化的 Dockerfile 和 docker-compose 配置。

核心能力

Dockerfile 编写与优化
docker-compose 多服务编排
镜像体积优化
多阶段构建
容器调试与问题排查

Dockerfile 最佳实践

基础模板

# 使用官方基础镜像，指定具体版本
FROM node:20-alpine AS base

# 设置工作目录
WORKDIR /app

# 先复制依赖文件（利用缓存）
COPY package*.json ./

# 安装依赖
RUN npm ci --only=production

# 复制源代码
COPY . .

# 非root 用户运行
USER node

# 暴露端口
EXPOSE 3000

# 启动命令
CMD ["node", "server.js"]

多阶段构建（推荐）

# 构建阶段
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

# 生产阶段
FROM node:20-alpine AS production
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
USER node
EXPOSE 3000
CMD ["node", "dist/server.js"]

##镜像优化指南

1. 选择合适的基础镜像

镜像	大小	适用场景
`alpine`	~5MB	生产环境首选
`slim`	~80MB	需要更多系统工具
`bookworm`	~120MB	完整 Debian 环境

2. 减少层数和大小

# ❌ 不推荐：多个RUN 指令
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get clean

# ✅ 推荐：合并 RUN 指令
RUN apt-get update && \
    apt-get install -y --no-install-recommends curl && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

3. 使用 .dockerignore

node_modules
.git
.env
*.log
dist
coverage
.DS_Store

docker-compose 模板

开发环境

version: '3.8'

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile.dev
    ports:
      - "3000:3000"
    volumes:
      - .:/app
      - /app/node_modules
    environment:
      - NODE_ENV=development
    depends_on:
      - db
      - redis

  db:
    image: postgres:15-alpine
    environment:
      POSTGRES_USER: dev
      POSTGRES_PASSWORD: devpass
      POSTGRES_DB: myapp
    volumes:
      - postgres_data:/var/lib/postgresql/data
    ports:
      - "5432:5432"

  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"

volumes:
  postgres_data:

常用命令速查

# 构建镜像
docker build -t myapp:latest .

# 查看镜像大小
docker images myapp

# 分析镜像层
docker history myapp:latest

# 进入运行中的容器
docker exec -it<container_id> sh

# 查看容器日志
docker logs -f <container_id>

# 清理未使用资源
docker system prune -a

# 导出镜像
docker save myapp:latest | gzip > myapp.tar.gz

调试技巧

1. 构建失败调试

# 使用 --progress=plain 查看详细输出
docker build --progress=plain -t myapp .

# 从特定阶段开始构建
docker build --target builder -t myapp:builder .

2. 容器运行调试

# 覆盖入口点进入 shell
docker run -it --entrypoint sh myapp

# 检查容器文件系统
docker run --rm -it myapp ls -la /app

安全建议

不使用 root 用户：始终使用 USER 指令
扫描漏洞：使用 docker scout 或 trivy
固定版本：避免使用 latest 标签
最小权限：只安装必要的包
敏感信息：使用 secrets，不要硬编码

参考资源

Docker 官方文档：https://docs.docker.com
Dockerfile 最佳实践：https://docs.docker.com/develop/develop-images/dockerfile_best-practices/
Docker Compose 规范：https://docs.docker.com/compose/compose-file/

docker-helper

When & Why to Use This Skill

Use Cases