chroot script for testing aarch64

alpine-chroot.sh

#!/bin/sh
#
# This simple script is setting up a Alpine Linux installation in a chroot.
# chroot will be placed in the current working directory.
#
# Most parts of this script are written down at
# http://wiki.alpinelinux.org/wiki/Setting_up_the_build_environment_in_chroot
#
# Licensed under GPLv2
#
# Copyright (c) 2011-2019 Fabian Affolter <fabian at affolter-engineering.ch>
# Copyright (c) 2019 Lorenzo Giuliani <lorenzo at frenzart.com>

# default variables
MIRROR=http://dl-5.alpinelinux.org/alpine
ARCH=${ARCH:-"armhf"}
VERSION=v3.9
APK_TOOL_VERSION=${APK_TOOL_VERSION:-"2.10.3-r1"}

# Check if root
checkroot() {
    # Root has $UID 0
    ROOT_UID=0
    if [ "$UID" != "$ROOT_UID" ]
    then
        echo "You are not root. Please use su to become root."
        exit 0
    fi
}

checkdir() {
    if [ -d $CHROOT ]
    then
        echo "$CHROOT already exists."
        echo "To start your Alpine chroot:"
        echo "sudo chroot $CHROOT /bin/sh -l"
        exit 0
    else
        mkdir -p $CHROOT
    fi
}

usage() {
    cat <<EUSAGE

USAGE: ./alpine-chroot [flags] <command>

Flags:
    -h --help               this message
    --arch=<value>          CPU architecture [aarch64 armhf armv7 ppc64le s390x x86 x86_64] (default=${ARCH})
    --apk-tool-version      apk-tool version (default=${APK_TOOL_VERSION})
    --mirror                Alpine linux mirror (default=${MIRROR})
EUSAGE
}

while [ "$1" != "" ]; do
    PARAM=`echo $1 | awk -F= '{print $1}'`
    VALUE=`echo $1 | awk -F= '{print $2}'`
    case $PARAM in
        -h | --help)
            usage
            exit 0
            ;;
        --mirror)
            MIRROR=$VALUE
            ;;
        --arch)
            ARCH=$VALUE
            ;;
        --apk-tool-version)
            APK_TOOL_VERSION=$VALUE
            ;;
        enter | create)
            ACTION=$PARAM
            ;;
        *)
            echo "ERROR: unknown parameter \"$PARAM\""
            usage
            exit 1
            ;;
    esac
    shift
done

CHROOT=alpine-chroot-${ARCH}
APK_TOOL="apk-tools-static-${APK_TOOL_VERSION}.apk"

# create a new chroot
create() {
    # download apk-tool
    wget -O - $MIRROR/$VERSION/main/$ARCH/$APK_TOOL | tar -xzf -
    ./sbin/apk.static \
        -X $MIRROR/$VERSION/main \
        -U \
        --allow-untrusted \
        --root ././$CHROOT \
        --initdb add alpine-base alpine-sdk

    mkdir -p $CHROOT{/root,/etc/apk,/proc}
    mount --bind /proc $CHROOT/proc
    mknod -m 666 $CHROOT/dev/full c 1 7
    mknod -m 666 $CHROOT/dev/ptmx c 5 2
    mknod -m 644 $CHROOT/dev/random c 1 8
    mknod -m 644 $CHROOT/dev/urandom c 1 9
    mknod -m 666 $CHROOT/dev/zero c 1 5
    mknod -m 666 $CHROOT/dev/tty c 5 0
    rm -f $CHROOT/dev/null
    mknod -m 666 $CHROOT/dev/null c 1 3
    chmod 777 /dev/shm

    cp /etc/resolv.conf $CHROOT/etc/
    echo "$MIRROR/$VERSION/main" >  $CHROOT/etc/apk/repositories

    # Cleaning up
    rm -rf sbin
    rm -f APK_TOOL

    cat <<EEND

Your Alpine Linux installation in '$CHROOT' is ready.

To start Alpine execute as root:

    $0 --arch=$ARCH start

or manually:

    mount -o bind ./aports $CHROOT/aports
    chroot $CHROOT /bin/sh -l

EEND
}


case $ACTION in
    enter)
        checkroot
        echo "mounting ./aports as /aports"
        mount -o bind ./aports $CHROOT/aports
        echo "entering chroot..."
        chroot $CHROOT /bin/sh -l
        ;;
    create)
        checkroot
        checkdir
        create
        ;;
    *)
        usage
        ;;
esac