Docker实现将镜像从1.2GB压缩到200MB的优化指南

# 原始Dockerfile - 存在多个问题
FROM node:16
WORKDIR /app
COPY . .
RUN npm install
RUN npm run build
EXPOSE 3000
CMD ["npm", "start"]

# 分析镜像层级和大小
docker history my-app:original --format "table {{.CreatedBy}}\t{{.Size}}"

# 优化后的基础镜像选择
FROM node:16-alpine AS base

# 安装必要的系统依赖
RUN apk add --no-cache \
    python3 \
    make \
    g++ \
    && rm -rf /var/cache/apk/*

# 多阶段构建Dockerfile
FROM node:16-alpine AS builder

# 设置工作目录
WORKDIR /app

# 复制package文件
COPY package*.json ./

# 安装所有依赖（包括开发依赖）
RUN npm ci --only=production --silent

# 复制源代码
COPY src/ ./src/
COPY public/ ./public/
COPY *.config.js ./

# 构建应用
RUN npm run build

# 生产阶段
FROM node:16-alpine AS production

# 创建非root用户
RUN addgroup -g 1001 -S nodejs && \
    adduser -S nextjs -u 1001

WORKDIR /app

# 从构建阶段复制必要文件
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package*.json ./

# 设置用户权限
USER nextjs

EXPOSE 3000

CMD ["node", "dist/index.js"]

# 分析依赖大小
npm ls --depth=0 --prod --parseable | xargs du -sh

# 使用npm-check-unused检查未使用依赖
npx npm-check-unused

// package.json优化策略
{
  "dependencies": {
    // 仅保留运行时必需依赖
    "express": "^4.18.0",
    "compression": "^1.7.4"
  },
  "devDependencies": {
    // 开发依赖不会进入生产镜像
    "webpack": "^5.70.0",
    "babel-loader": "^8.2.0",
    "@types/node": "^17.0.0"
  },
  "scripts": {
    "build": "webpack --mode=production",
    "start": "node dist/index.js"
  }
}

# 优化的依赖安装策略
FROM node:16-alpine AS deps

WORKDIR /app
COPY package*.json ./

# 使用npm ci进行确定性安装
RUN npm ci --only=production --silent --no-audit --no-fund

# 清理npm缓存
RUN npm cache clean --force && \
    rm -rf /tmp/* /var/tmp/* /root/.npm

# .dockerignore - 排除不必要文件
node_modules
npm-debug.log*
.git
.gitignore
README.md
.env
.nyc_output
coverage
.coverage
.cache
.parcel-cache
dist
.DS_Store
*.log
.vscode
.idea

# 合并RUN指令减少层级
RUN apk add --no-cache python3 make g++ && \
    npm ci --only=production --silent && \
    npm cache clean --force && \
    apk del python3 make g++ && \
    rm -rf /var/cache/apk/* /tmp/* /var/tmp/*

# 利用Docker构建缓存
FROM node:16-alpine AS base

# 先复制package文件，利用缓存
COPY package*.json ./
RUN npm ci --only=production

# 后复制源代码，避免依赖重新安装
COPY . .
RUN npm run build

# 构建时压缩优化
docker build --compress --squash -t my-app:optimized .

# 使用dive工具分析镜像
dive my-app:optimized

# 测试镜像拉取时间
time docker pull my-app:original  # 原始镜像
time docker pull my-app:optimized # 优化后镜像

# 测试容器启动时间
time docker run --rm my-app:optimized

# CI/CD中的镜像大小检查
name: Image Size Check
on: [push, pull_request]

jobs:
  size-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Build and check size
        run: |
          docker build -t test-image .
          SIZE=$(docker images test-image --format "{{.Size}}")
          echo "Image size: $SIZE"
          # 设置大小阈值告警
          if [[ $(docker images test-image --format "{{.Size}}" | grep -o '[0-9]*') -gt 250 ]]; then
            echo "Warning: Image size exceeds 250MB"
            exit 1
          fi

# 问题1：Alpine镜像缺少glibc
# 解决方案：安装glibc兼容层
RUN apk add --no-cache libc6-compat

# 问题2：Node.js原生模块编译失败
# 解决方案：安装构建工具
RUN apk add --no-cache --virtual .build-deps \
    python3 make g++ && \
    npm install && \
    apk del .build-deps

# 问题3：时区问题
# 解决方案：设置时区
RUN apk add --no-cache tzdata && \
    cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime && \
    echo "Asia/Shanghai" > /etc/timezone && \
    apk del tzdata

# 生产环境优化配置
FROM node:16-alpine

# 设置Node.js生产环境变量
ENV NODE_ENV=production
ENV NODE_OPTIONS="--max-old-space-size=512"

# 优化npm配置
RUN npm config set registry https://registry.npmmirror.com && \
    npm config set cache /tmp/.npm && \
    npm config set prefer-offline true

WORKDIR /app

# 健康检查
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
    CMD node healthcheck.js

EXPOSE 3000
CMD ["node", "dist/index.js"]