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Mark C's questions

Martin Hope
Mark C
Asked: 2020-03-26 06:45:41 +0800 CST
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我正在努力将现有的 CentOS 7 Docker 映像构建过程转换为使用 Buildah，但我遇到了mknod.

目前我使用以下 Dockerfile 来构建一个新图像。所以基本上是用一个镜像来构建一个镜像，以避免对构建主机的依赖。我这样运行它：

docker build -f Dockerfile.builder -t centosbuilder:latest . && \
docker run --rm centosbuilder:latest | docker import - mycentos:latest

这是 Dockerfile：

FROM centos:7

ENV ROOTFS /image_build_root
ENV TMPDIR /tmp/image_build

WORKDIR ${TMPDIR}
RUN mkdir -p ${ROOTFS}
RUN mkdir -m 755 ${ROOTFS}/dev && \
    mknod -m 600 ${ROOTFS}/dev/console c 5 1 && \
    mknod -m 600 ${ROOTFS}/dev/initctl p && \
    mknod -m 666 ${ROOTFS}/dev/full c 1 7 && \
    mknod -m 666 ${ROOTFS}/dev/null c 1 3 && \
    mknod -m 666 ${ROOTFS}/dev/ptmx c 5 2 && \
    mknod -m 666 ${ROOTFS}/dev/random c 1 8 && \
    mknod -m 666 ${ROOTFS}/dev/tty c 5 0 && \
    mknod -m 666 ${ROOTFS}/dev/tty0 c 4 0 && \
    mknod -m 666 ${ROOTFS}/dev/urandom c 1 9 && \
    mknod -m 666 ${ROOTFS}/dev/zero c 1 5
RUN yum --installroot=${ROOTFS} --releasever=7 --setopt=tsflags=nodocs --setopt=group_package_types=mandatory -y groupinstall Core
RUN yum --installroot=${ROOTFS} -y clean all
RUN echo "NETWORKING=yes" > ${ROOTFS}/etc/sysconfig/network && \
    echo "HOSTNAME=localhost.localdomain" > ${ROOTFS}/etc/sysconfig/network
RUN rm -rf ${ROOTFS}/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive} && \
    #  docs and man pages
    rm -rf ${ROOTFS}/usr/share/{man,doc,info,gnome/help} && \
    #  cracklib
    rm -rf ${ROOTFS}/usr/share/cracklib && \
    #  i18n
    rm -rf ${ROOTFS}/usr/share/i18n && \
    #  yum cache
    rm -rf ${ROOTFS}/var/cache/yum && \
    mkdir -p --mode=0755 ${ROOTFS}/var/cache/yum && \
    #  sln
    rm -rf ${ROOTFS}/sbin/sln && \
    #  ldconfig
    rm -rf ${ROOTFS}/etc/ld.so.cache ${ROOTFS}/var/cache/ldconfig && \
    mkdir -p --mode=0755 ${ROOTFS}/var/cache/ldconfig
CMD /usr/bin/tar -cf - -C ${ROOTFS} .

使用 Buildah，我在这一行遇到了我的第一个错误：

$ buildah run "${BUILDER}" mknod -m 600 "${ROOTFS}/dev/console" c 5 1
/usr/bin/mknod: '/image_build_root/dev/console': Operation not permitted
ERRO exit status 1

我尝试以 root 身份运行我的构建脚本（见下文），但无济于事。我假设可能CAP_MKNOD没有设置该功能，但即使我手动启用它，我也会收到相同的错误。

构建脚本：

#!/bin/bash -x

set -e

ROOTFS=/image_build_root
TMPDIR=/tmp/image_build

BUILDER="$(buildah from docker.io/library/centos:7)"
buildah config --workingdir "${TMPDIR}" "${BUILDER}"
buildah run "${BUILDER}" mkdir -p "${ROOTFS}"
buildah run "${BUILDER}" mkdir -m 755 "${ROOTFS}/dev"
buildah run --cap-add=CAP_MKNOD "${BUILDER}" mknod -m 600 "${ROOTFS}/dev/console" c 5 1
buildah run "${BUILDER}" mknod -m 600 "${ROOTFS}/dev/initctl" p
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/full" c 1 7
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/null" c 1 3
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/ptmx" c 5 2
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/random" c 1 8
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/tty" c 5 0
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/tty0" c 4 0
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/urandom" c 1 9
buildah run "${BUILDER}" mknod -m 666 "${ROOTFS}/dev/zero" c 1 5
buildah run "${BUILDER}" yum \
    --installroot="${ROOTFS}" \
    --releasever=7 \
    --setopt=tsflags=nodocs \
    --setopt=group_package_types=mandatory \
    -y \
    groupinstall Core
buildah run "${BUILDER}" yum --installroot="${ROOTFS}" -y clean all
buildah run "${BUILDER}" echo "NETWORKING=yes" > "${ROOTFS}/etc/sysconfig/network"
buildah run "${BUILDER}" echo "HOSTNAME=localhost.localdomain" > "${ROOTFS}/etc/sysconfig/network"
buildah run "${BUILDER}" rm -rf \
    "${ROOTFS}/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}" \
    "${ROOTFS}/usr/share/{man,doc,info,gnome/help}" \
    "${ROOTFS}/usr/share/cracklib" \
    "${ROOTFS}/usr/share/i18n" \
    "${ROOTFS}/var/cache/yum" \
    "${ROOTFS}/sbin/sln" \
    "${ROOTFS}/etc/ld.so.cache" \
    "${ROOTFS}/var/cache/ldconfig"
buildah run "${BUILDER}" mkdir -p --mode=0755 "${ROOTFS}/var/cache/yum"
buildah run "${BUILDER}" mkdir -p --mode=0755 "${ROOTFS}/var/cache/ldconfig"
buildah config --cmd /usr/bin/tar -cf - -C "${ROOTFS}" . "${BUILDER}"
buildah commit "${BUILDER}" centos7builder
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