Docker镜像构建与优化技巧：减小镜像体积

基础优化策略

1. 选择合适的基础镜像

• Alpine Linux：基于musl libc和busybox，镜像体积极小（约5MB）
• Distroless：Google提供的只包含应用程序及其依赖的镜像
• Slim版本：如python:slim、node:alpine

# 不推荐
FROM ubuntu:latest

# 推荐
FROM alpine:latest
# 或
FROM gcr.io/distroless/base

2. 多阶段构建（Multi-stage builds）

# 第一阶段：构建环境
FROM golang:1.16 AS builder
WORKDIR /app
COPY . .
RUN go build -o myapp .

# 第二阶段：运行环境
FROM alpine:latest
WORKDIR /app
COPY --from=builder /app/myapp .
CMD ["./myapp"]

3. 合并RUN指令减少镜像层

# 不推荐
RUN apt-get update
RUN apt-get install -y package1
RUN apt-get install -y package2
RUN rm -rf /var/lib/apt/lists/*

# 推荐
RUN apt-get update && \
    apt-get install -y package1 package2 && \
    rm -rf /var/lib/apt/lists/*

进阶优化技巧

4. 清理不必要的文件

RUN apt-get update && \
    apt-get install -y --no-install-recommends package1 && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

5. 使用.dockerignore文件

.git
node_modules
*.log
*.tmp
Dockerfile
README.md

6. 最小化COPY/ADD操作

# 不推荐
COPY . .

# 推荐
COPY package.json .
COPY src/ src/

7. 压缩静态资源

FROM node:alpine AS builder
WORKDIR /app
COPY . .
RUN npm install && npm run build

FROM nginx:alpine
COPY --from=builder /app/dist /usr/share/nginx/html
RUN gzip -k /usr/share/nginx/html/*

特定语言优化

8. Python应用优化

FROM python:3.9-slim

# 使用虚拟环境
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# 先安装依赖，再复制代码
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

COPY . .

9. Node.js应用优化

FROM node:alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci --production

FROM node:alpine
WORKDIR /app
COPY --from=builder /app/node_modules ./node_modules
COPY . .

10. Java应用优化

FROM maven:3.6-jdk-11 AS build
WORKDIR /app
COPY pom.xml .
RUN mvn dependency:go-offline
COPY src ./src
RUN mvn package

FROM openjdk:11-jre-slim
COPY --from=build /app/target/app.jar /app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

镜像分析工具

1. Dive：分析镜像各层内容

   dive <image-name>
   

2. docker history：查看镜像构建历史

   docker history <image-name>
   

3. docker-slim：自动优化镜像

   docker-slim build --target <image-name>
   

通过综合应用这些技巧，通常可以将镜像体积减小50%-90%，同时保持应用功能的完整性。