# 拉取并查看镜像大小
$ docker images
REPOSITORY   TAG          SIZE
busybox      latest       1.24MB
alpine       3.19         5.61MB
debian       slim         74.1MB
ubuntu       22.04        77.8MB

# Dockerfile - 基于 scratch 的最小镜像
FROM scratch

# 复制静态编译的 BusyBox
COPY busybox /busybox

# 创建基本目录
RUN ["/busybox", "mkdir", "-p", "/bin", "/sbin", "/usr/bin", "/usr/sbin", \
     "/tmp", "/proc", "/sys", "/dev", "/etc", "/var", "/root"]

# 创建符号链接
RUN ["/busybox", "--install", "-s"]

# 设置默认 Shell
CMD ["/bin/sh"]

# 编译静态 BusyBox
$ make defconfig
$ sed -i 's/# CONFIG_STATIC is not set/CONFIG_STATIC=y/' .config
$ make -j$(nproc)

# 构建镜像
$ docker build -t my-busybox .

# 查看大小
$ docker images my-busybox
REPOSITORY   TAG       SIZE
my-busybox   latest    1.24MB

# 运行
$ docker run -it my-busybox
/ # ls
bin      dev      etc      proc     root     sbin     sys      tmp      usr      var
/ # echo "Hello from BusyBox container!"
Hello from BusyBox container!

# Dockerfile - 多阶段构建（从源码编译 BusyBox）
# 阶段一：编译
FROM ubuntu:22.04 AS builder

RUN apt-get update && \
    apt-get install -y build-essential gcc make wget bzip2 && \
    rm -rf /var/lib/apt/lists/*

ARG BUSYBOX_VERSION=1.36.1

RUN wget https://busybox.net/downloads/busybox-${BUSYBOX_VERSION}.tar.bz2 && \
    tar xjf busybox-${BUSYBOX_VERSION}.tar.bz2 && \
    cd busybox-${BUSYBOX_VERSION} && \
    make defconfig && \
    sed -i 's/# CONFIG_STATIC is not set/CONFIG_STATIC=y/' .config && \
    make -j$(nproc) && \
    make CONFIG_PREFIX=/output install

# 阶段二：运行时
FROM scratch

COPY --from=builder /output /

CMD ["/bin/sh"]

# Dockerfile - 运行 Go 应用的最小镜像
FROM golang:1.21-alpine AS builder

WORKDIR /app
COPY go.mod go.sum ./
RUN go mod download

COPY . .
RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /myapp .

# 运行时镜像
FROM busybox

COPY --from=builder /myapp /usr/local/bin/myapp

# 使用 mdev 设备管理
RUN mkdir -p /etc/init.d && \
    echo '#!/bin/sh' > /etc/init.d/rcS && \
    chmod +x /etc/init.d/rcS

EXPOSE 8080
USER nobody
CMD ["/usr/local/bin/myapp"]

FROM scratch

# 从 builder 阶段复制 CA 证书
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY busybox /busybox
RUN ["/busybox", "--install", "-s"]

# 现在可以使用 HTTPS
RUN ["/bin/wget", "https://example.com"]

FROM busybox

# 复制应用和配置
COPY myapp /usr/local/bin/
COPY config.yml /etc/myapp/
COPY entrypoint.sh /entrypoint.sh

RUN chmod +x /entrypoint.sh /usr/local/bin/myapp

EXPOSE 8080
ENTRYPOINT ["/entrypoint.sh"]
CMD ["--config", "/etc/myapp/config.yml"]

# Alpine 基础镜像
FROM alpine:3.19

# 安装软件包
RUN apk add --no-cache \
    curl \
    wget \
    bash \
    python3 \
    nodejs

# 使用 apk 搜索包
# docker run -it alpine:3.19
/ # apk search python3
python3-3.11.6-r0
python3-dev-3.11.6-r0
...

# 仅需要单一静态二进制 → busybox
FROM busybox
COPY myapp /myapp
CMD ["/myapp"]

# 需要运行时环境 → alpine
FROM alpine
RUN apk add --no-cache python3 py3-pip
COPY app.py /app.py
CMD ["python3", "/app.py"]

# 需要完整生态 → debian
FROM debian:slim
RUN apt-get update && apt-get install -y python3 python3-pip

# 1. 使用多阶段构建
FROM golang:1.21 AS builder
RUN go build -ldflags="-s -w" -o /app .

FROM busybox
COPY --from=builder /app /app

# 2. 合并 RUN 指令
RUN mkdir -p /app && \
    cp file1 /app/ && \
    cp file2 /app/ && \
    rm -rf /tmp/*

# 3. 使用 .dockerignore
# .dockerignore
.git
*.md
test/
vendor/

# 4. 清理包管理器缓存
RUN apk add --no-cache package  # Alpine
RUN apt-get clean && rm -rf /var/lib/apt/lists/*  # Debian

FROM busybox

# 不以 root 运行
RUN adduser -D -u 1000 appuser
USER appuser

# 只读文件系统（运行时）
# docker run --read-only ...

# 限制资源
# docker run --memory=100m --cpus=0.5 ...

# 丢弃能力
# docker run --cap-drop=ALL ...

# 在 ARM 设备上运行 Docker
# 1. 安装 Docker
$ curl -fsSL https://get.docker.com | sh

# 2. 拉取 ARM 镜像
$ docker pull busybox:latest  # 自动选择架构

# 3. 运行
$ docker run -it busybox

# Dockerfile.arm32v7
FROM arm32v7/busybox:latest

COPY qemu-arm-static /usr/bin/
COPY myapp /usr/local/bin/

CMD ["/usr/local/bin/myapp"]

# 交叉构建镜像
$ docker buildx build --platform linux/arm/v7 -t myapp:arm32 .

# debug-pod.yaml - 调试 Pod
apiVersion: v1
kind: Pod
metadata:
  name: debug
spec:
  containers:
  - name: debug
    image: busybox
    command: ['sleep', '3600']
    resources:
      limits:
        memory: "64Mi"
        cpu: "100m"
  restartPolicy: Never

# 创建调试 Pod
$ kubectl apply -f debug-pod.yaml

# 进入调试容器
$ kubectl exec -it debug -- /bin/sh

# 网络诊断
$ kubectl exec debug -- nslookup kubernetes.default
$ kubectl exec debug -- wget -qO- http://service:8080/health

# 交互式运行
$ docker run -it busybox /bin/sh

# 后台运行
$ docker run -d --name myapp busybox sleep 3600

# 进入运行中的容器
$ docker exec -it myapp /bin/sh

# 查看容器日志
$ docker logs myapp

# 复制文件
$ docker cp myapp:/etc/hosts ./hosts

# 容器导出为 tar
$ docker export myapp > myapp.tar

# 从 tar 导入镜像
$ docker import myapp.tar myapp:latest

# 查看容器资源使用
$ docker stats myapp