# 方案1：一个 Dockerfile，最终镜像巨大
FROM golang:1.21
WORKDIR /build
COPY . .
RUN go build -o myapp .
# 镜像包含 Go 编译器、编译工具链，>1GB

# 方案2：两个 Dockerfile，脚本串联（繁琐）
# Dockerfile.build
FROM golang:1.21 AS builder
WORKDIR /build
COPY . .
RUN go build -o myapp .

# Dockerfile.prod
FROM alpine:3.18
COPY --from=builder /build/myapp /myapp
# 需要外部构建流程来配合

flowchart LR
    subgraph "传统方式（~1.2GB）"
        A1[golang:1.21] --> A2[编译工具+依赖]
        A2 --> A3[二进制作品]
        A3 --> A4["最终镜像\n（包含编译器！）"]
    end

    subgraph "多阶段构建（~15MB）"
        B1["阶段1: golang:1.21"] --> B2[编译]
        B2 --> B3["阶段2: alpine:3.18"]
        B3 --> B4["仅复制二进制\n最终镜像极小"]
    end

# === 阶段1：构建 ===
FROM golang:1.21 AS builder
WORKDIR /app

# 利用缓存：先复制依赖文件
COPY go.mod go.sum ./
RUN go mod download

# 构建二进制
COPY . .
RUN CGO_ENABLED=0 GOOS=linux go build -o /app/server .

# === 阶段2：运行 ===
FROM alpine:3.18
RUN apk --no-cache add ca-certificates tzdata

WORKDIR /app
COPY --from=builder /app/server .

EXPOSE 8080
CMD ["./server"]

docker build -t myapp:latest .
docker images myapp
# REPOSITORY   TAG       IMAGE ID       SIZE
# myapp       latest    abc123def456    15.2MB

# === 阶段1：安装依赖和构建 ===
FROM node:18-alpine AS builder
WORKDIR /build

COPY package*.json ./
RUN npm ci

COPY . .
RUN npm run build  # 假设生成 dist/ 目录

# === 阶段2：生产运行 ===
FROM node:18-alpine
WORKDIR /app

# 只复制生产依赖和构建产物
COPY --from=builder /build/node_modules ./node_modules
COPY --from=builder /build/dist ./dist
COPY --from=builder /build/package.json .

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

# === 阶段1：构建依赖 ===
FROM python:3.11-slim AS builder

RUN apt-get update && \
    apt-get install -y --no-install-recommends \
    build-essential && \
    rm -rf /var/lib/apt/lists/*

WORKDIR /build
COPY requirements.txt .
RUN pip install --user -r requirements.txt

# === 阶段2：运行 ===
FROM python:3.11-slim

COPY --from=builder /root/.local /root/.local
COPY . /app
WORKDIR /app

# 确保 local/bin 在 PATH 中
ENV PATH=/root/.local/bin:$PATH

CMD ["python", "app.py"]

# 可以给每个阶段命名，通过名字复制
FROM maven:3.9-eclipse-temurin-17 AS builder
WORKDIR /build
COPY pom.xml .
RUN mvn dependency:go-offline
COPY src ./src
RUN mvn package -DskipTests

FROM eclipse-temurin:17-jre-alpine
COPY --from=builder /build/target/*.jar /app/app.jar
CMD ["java", "-jar", "/app/app.jar"]

FROM --platform=$BUILDPLATFORM golang:1.21 AS builder
ARG TARGETOS TARGETARCH
WORKDIR /app
COPY . .
RUN GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o server .

FROM alpine:3.18
COPY --from=builder /app/server /server
CMD ["/server"]

# 构建多架构镜像
docker buildx build --platform linux/amd64,linux/arm64 -t myapp:latest --push .

FROM ubuntu:22.04 AS base
RUN apt update && apt install -y curl  # 可能很大
RUN echo "shared script" > /script.sh

FROM alpine:3.18
# 只复制脚本文件，跳过 curl
COPY --from=base /script.sh /script.sh
RUN cat /script.sh && rm /script.sh
CMD ["echo", "hello"]

# 如果你只需要编译产物，不需要最终镜像
docker build --target builder -t myapp-builder .
# 构建在 builder 阶段结束后停止

flowchart TD
    A[Go Web 应用] --> B[单阶段构建: golang:1.21]
    A --> C[多阶段构建: alpine:3.18]
    A --> D[多阶段构建: scratch]

    B --> B1["~1.2GB"]
    C --> C1["~15MB"]
    D --> D1["~8MB"]

    C1 --> E["减少 98.7%"]
    D1 --> F["减少 99.3%"]

    style B1 fill:#ffcdd2
    style C1 fill:#c8e6c9
    style D1 fill:#c8e6c9