如何从头构建一个只有bash的镜像

说明：本次生成的镜像是centos7版本的

从官网下载对应的脚本：

https://github.com/moby/moby/blob/master/contrib/mkimage-yum.sh

上面这个脚本就是centos官网用于创建docker镜像的

1、脚本具体的信息如下：

#!/usr/bin/env bash
#
# Create a base CentOS Docker image.
#
# This script is useful on systems with yum installed (e.g., building
# a CentOS image on CentOS).  See contrib/mkimage-rinse.sh for a way
# to build CentOS images on other systems.

set -e

usage() {
    cat << EOOPTS
$(basename $0) [OPTIONS] <name>
OPTIONS:
  -p "<packages>"  The list of packages to install in the container.
                   The default is blank. Can use multiple times.
  -g "<groups>"    The groups of packages to install in the container.
                   The default is "Core". Can use multiple times.
  -y <yumconf>     The path to the yum config to install packages from. The
                   default is /etc/yum.conf for Centos/RHEL and /etc/dnf/dnf.conf for Fedora
  -t <tag>         Specify Tag information.
                   default is reffered at /etc/{redhat,system}-release
EOOPTS
    exit 1
}

# option defaults
yum_config=/etc/yum.conf
if [ -f /etc/dnf/dnf.conf ] && command -v dnf &> /dev/null; then
    yum_config=/etc/dnf/dnf.conf
    alias yum=dnf
fi
# for names with spaces, use double quotes (") as install_groups=('Core' '"Compute Node"')
install_groups=()
install_packages=()
version=
while getopts ":y:p:g:t:h" opt; do
    case $opt in
        y)
            yum_config=$OPTARG
            ;;
        h)
            usage
            ;;
        p)
            install_packages+=("$OPTARG")
            ;;
        g)
            install_groups+=("$OPTARG")
            ;;
        t)
            version="$OPTARG"
            ;;
        \?)
            echo "Invalid option: -$OPTARG"
            usage
            ;;
    esac
done
shift $((OPTIND - 1))
name=$1

if [[ -z $name ]]; then
    usage
fi

# default to Core group if not specified otherwise
if [ ${#install_groups[*]} -eq 0 ]; then
    install_groups=('Core')
fi

target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)

set -x

mkdir -m 755 "$target"/dev
mknod -m 600 "$target"/dev/console c 5 1
mknod -m 600 "$target"/dev/initctl p
mknod -m 666 "$target"/dev/full c 1 7
mknod -m 666 "$target"/dev/null c 1 3
mknod -m 666 "$target"/dev/ptmx c 5 2
mknod -m 666 "$target"/dev/random c 1 8
mknod -m 666 "$target"/dev/tty c 5 0
mknod -m 666 "$target"/dev/tty0 c 4 0
mknod -m 666 "$target"/dev/urandom c 1 9
mknod -m 666 "$target"/dev/zero c 1 5

# amazon linux yum will fail without vars set
if [ -d /etc/yum/vars ]; then
    mkdir -p -m 755 "$target"/etc/yum
    cp -a /etc/yum/vars "$target"/etc/yum/
fi

if [[ -n "$install_groups" ]]; then
    yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
        --setopt=group_package_types=mandatory -y groupinstall "${install_groups[@]}"
fi

if [[ -n "$install_packages" ]]; then
    yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
        --setopt=group_package_types=mandatory -y install "${install_packages[@]}"
fi

yum -c "$yum_config" --installroot="$target" -y clean all

cat > "$target"/etc/sysconfig/network << EOF
NETWORKING=yes
HOSTNAME=localhost.localdomain
EOF

# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb --keep-services "$target".
#  locales
rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
#  docs and man pages
rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
#  cracklib
rm -rf "$target"/usr/share/cracklib
#  i18n
rm -rf "$target"/usr/share/i18n
#  yum cache
rm -rf "$target"/var/cache/yum
mkdir -p --mode=0755 "$target"/var/cache/yum
#  sln
rm -rf "$target"/sbin/sln
#  ldconfig
rm -rf "$target"/etc/ld.so.cache "$target"/var/cache/ldconfig
mkdir -p --mode=0755 "$target"/var/cache/ldconfig

if [ -z "$version" ]; then
    for file in "$target"/etc/{redhat,system}-release; do
        if [ -r "$file" ]; then
            version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' "$file")"
            break
        fi
    done
fi

if [ -z "$version" ]; then
    echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
    version=$name
fi

tar --numeric-owner -c -C "$target" . | docker import - $name:$version

docker run -i -t --rm $name:$version /bin/bash -c 'echo success'

rm -rf "$target"

 

该脚本的具体用法如下：

bash 脚本名字 -p "包名" -g "组名"  镜像名字

2、修改官方的脚本

修改以后脚本如下：

#!/usr/bin/env bash
#
# Create a base CentOS Docker image.
#
# This script is useful on systems with yum installed (e.g., building
# a CentOS image on CentOS).  See contrib/mkimage-rinse.sh for a way
# to build CentOS images on other systems.

set -e

usage() {
    cat << EOOPTS
$(basename $0) [OPTIONS] <name>
OPTIONS:
  -p "<packages>"  The list of packages to install in the container.
                   The default is blank. Can use multiple times.
  -g "<groups>"    The groups of packages to install in the container.
                   The default is "Core". Can use multiple times.
  -y <yumconf>     The path to the yum config to install packages from. The
                   default is /etc/yum.conf for Centos/RHEL and /etc/dnf/dnf.conf for Fedora
  -t <tag>         Specify Tag information.
                   default is reffered at /etc/{redhat,system}-release
EOOPTS
    exit 1
}

# option defaults
yum_config=/etc/yum.conf
if [ -f /etc/dnf/dnf.conf ] && command -v dnf &> /dev/null; then
    yum_config=/etc/dnf/dnf.conf
    alias yum=dnf
fi
# for names with spaces, use double quotes (") as install_groups=('Core' '"Compute Node"')
install_groups=()
install_packages=()
version=
while getopts ":y:p:g:t:h" opt; do
    case $opt in
        y)
            yum_config=$OPTARG
            ;;
        h)
            usage
            ;;
        p)
            install_packages+=("$OPTARG")
            ;;
        g)
            install_groups+=("$OPTARG")
            ;;
        t)
            version="$OPTARG"
            ;;
        \?)
            echo "Invalid option: -$OPTARG"
            usage
            ;;
    esac
done
shift $((OPTIND - 1))
name=$1

if [[ -z $name ]]; then
    usage
fi

# default to Core group if not specified otherwise
#if [ ${#install_groups[*]} -eq 0 ]; then
#    install_groups=('Core')
#fi

target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)

set -x

#mkdir -m 755 "$target"/dev
#mknod -m 600 "$target"/dev/console c 5 1
#mknod -m 600 "$target"/dev/initctl p
#mknod -m 666 "$target"/dev/full c 1 7
#mknod -m 666 "$target"/dev/null c 1 3
#mknod -m 666 "$target"/dev/ptmx c 5 2
#mknod -m 666 "$target"/dev/random c 1 8
#mknod -m 666 "$target"/dev/tty c 5 0
#mknod -m 666 "$target"/dev/tty0 c 4 0
#mknod -m 666 "$target"/dev/urandom c 1 9
#mknod -m 666 "$target"/dev/zero c 1 5

# amazon linux yum will fail without vars set
#if [ -d /etc/yum/vars ]; then
#    mkdir -p -m 755 "$target"/etc/yum
#    cp -a /etc/yum/vars "$target"/etc/yum/
#fi

#if [[ -n "$install_groups" ]]; then
#    yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
#        --setopt=group_package_types=mandatory -y groupinstall "${install_groups[@]}"
#fi

if [[ -n "$install_packages" ]]; then
    yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
        --setopt=group_package_types=mandatory -y install "${install_packages[@]}"
fi

yum -c "$yum_config" --installroot="$target" -y clean all

#cat > "$target"/etc/sysconfig/network << EOF
#NETWORKING=yes
#HOSTNAME=localhost.localdomain
#EOF

# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb --keep-services "$target".
#  locales
rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
#  docs and man pages
rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
#  cracklib
rm -rf "$target"/usr/share/cracklib
#  i18n
rm -rf "$target"/usr/share/i18n
#  yum cache
rm -rf "$target"/var/cache/yum
#mkdir -p --mode=0755 "$target"/var/cache/yum
#  sln
rm -rf "$target"/sbin/sln
#  ldconfig
rm -rf "$target"/etc/ld.so.cache "$target"/var/cache/ldconfig
mkdir -p --mode=0755 "$target"/var/cache/ldconfig

if [ -z "$version" ]; then
    for file in "$target"/etc/{redhat,system}-release; do
        if [ -r "$file" ]; then
            version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' "$file")"
            break
        fi
    done
fi

if [ -z "$version" ]; then
    echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
    version=$name
fi

#tar --numeric-owner -c -C "$target"      . | docker import - $name:$version
tar -cvf centos7_bash_new.tar   "$target"
#docker run -i -t --rm $name:$version /bin/bash -c 'echo success'

rm -rf "$target"

该脚本删除了官方脚本内部默认安装的Core组

脚本执行：

bash 脚本名字  -p "bash" centos7  // centos7这个没有实际的用处了，，这里只是为了脚本不报错，没来的既修改脚本

说明 ：上述的命令会只执行安装bash，然后在当前的目录下生成centos7_bash_new.tar包，

使用刚才生成的包创建docker镜像

# cat create_centos_new.sh |docker import - centos7_bash:7.7.1908

2、1查看生成的镜像