create-chroot

#!/bin/bash -eu
#
# Create a (kernel build) chroot
#


# -----------------------------------------------------------------------------
# Include the following packages

# The base DEB packages
DEB_INCLUDE=(
	fakeroot
	less
	perl-openssl-defaults  # [arm64] required due to dependency problems
	sudo
	tzdata
)

# Additional DEB packages (primarily for kernel builds)
DEB_PACKAGES=(
	asciidoc
	autoconf
	automake
	bc
	binutils-dev
	bison
	build-essential
	debhelper
	devscripts
	dh-systemd
	docbook-utils
	dpkg-dev
	flex
	gawk
	gcc-aarch64-linux-gnu
	gcc-arm-linux-gnueabihf
	gcc-i686-linux-gnu
	gcc-powerpc64le-linux-gnu
	gcc-s390x-linux-gnu gcc
	ghostscript
	git
	kernel-wedge
	kmod
	kpatch-build
	libaudit-dev
	libbabeltrace-devel
	libdistro-info-perl
	libdw-dev
	libelf-dev
	libiberty-dev
	liblzma-dev
	libmnl-devel
	libnewt-dev
	libnuma-dev
	libpci-dev
	libpng12-dev
	libssl-dev
	libtool
	libudev-dev
	libunwind8-dev
	liburi-perl
	makedumpfile
	openssl
	pkg-config
	python-dev
	python3-apt
	python3-launchpadlib
	python3-requests
	rsync
	sbsigntool
	sharutils
	transfig
	uuid-dev
	wget
	xmlto
)

# The base RPM packages
RPM_INCLUDE=(
	dnf-plugins-core
	fakeroot
	less
	sudo
	tzdata
)

# Additional RPM packages
RPM_PACKAGES=(
	fedora-packager
	rpmdevtools
	wget
	# Packages for kernel builds
	asciidoc
	audit-libs-devel
	bc
	binutils-devel
	bison
	bpftool
	dwarves
	elfutils-devel
	flex
	gcc
	git
	hostname
	java-devel
	kabi-dw
	libbpf-devel
	libcap-devel
	libcap-ng-devel
	llvm-toolset
	m4
	make
	ncurses-devel
	net-tools
	newt-devel
	nss-tools
	numactl-devel
	openssl-devel
	pciutils-devel
	perl-ExtUtils-Embed
	perl-devel
	perl-generators
	pesign
	python3-devel
	python3-docutils
	rsync
	xmlto
	xz-devel
	zlib-devel
)


# -----------------------------------------------------------------------------
# Exit handler

function out()
{
	local rc=${?}

	trap - EXIT INT HUP TERM

	# Unmount bound directories in case debootstrap failed
	if mount | grep -q " on ${BASEDIR}/" ; then
		mount | grep " on ${BASEDIR}/" | awk '{ print $3 }' | xargs umount
	fi

	# Emit a status message
	if [ "${rc}" -eq 0 ] ; then
		echo -e "\e[92mChroot created successfully\e[0m"
	else
		# Purge the chroot and config file
		if [ "${KEEP}" -eq 0 ] ; then
			rm -rf "${BASEDIR}" "/etc/schroot/chroot.d/${NAME}"
		fi
		echo -e "\e[91mError: Failed to create chroot!\e[0m" >&2
	fi

	exit "${rc}"
}


# -----------------------------------------------------------------------------
# Print variables

function print_vars()
{
	local var

	for var in "${@}" ; do
		printf "%-8s: %s\n" "${var}" "${!var}"
	done
}


# -----------------------------------------------------------------------------
# Create a Debian chroot

function debian_create_chroot()
{
	local components opts tz package

	case "${VENDOR}" in
		ubuntu)
			components="main,universe"
			;;
		*)
			components="main"
			;;
	esac

	if [ "${NO_CHECK_GPG}" -eq 1 ] ; then
		opts=("--no-check-gpg")
	fi

	if [ "${RELEASE}" = "precise" ] ; then
		# Debootstrap fails for Precise. Don't bail out in this case so we can
		# fix up the chroot later.
		set +e
	fi

	# Create the base chroot
	debootstrap \
		"${opts[@]}" \
		--include="$(IFS=, ; echo "${DEB_INCLUDE[*]}")" \
		--components="${components}" \
		--arch="${ARCH}" \
		"${RELEASE}" \
		"${BASEDIR}"

	if [ "${RELEASE}" = "precise" ] ; then
		# Fix the Precise chroot
		${SCHROOT} dpkg-divert --local --rename --add /sbin/initctl
		${SCHROOT} ln -s /bin/true /sbin/initctl
		set -e
	fi

	# Refresh the chroot
	${SCHROOT} apt-get -y update
	${SCHROOT} apt-get -y upgrade
	${SCHROOT} apt-get -y dist-upgrade

	# Set the chroot timezone to match the host
	tz=$(cat /etc/timezone)
	ln -fs "/usr/share/zoneinfo/${tz}" "${BASEDIR}/etc/localtime"
	${SCHROOT} dpkg-reconfigure -f noninteractive tzdata

	# Preseed kexec-tools
	${SCHROOT} bash -c "echo kexec-tools kexec-tools/load_kexec boolean false | debconf-set-selections"

	# Install the additional packages
	if [ "${BASE}" -eq 0 ] ; then
		for package in "${DEB_PACKAGES[@]}" ; do
			${SCHROOT} apt-get -y install "${package}" 2>/dev/null || true
		done
	fi

	# Clean the cache
	${SCHROOT} apt-get clean
}


# -----------------------------------------------------------------------------
# Create a Fedora chroot

function fedora_create_chroot()
{
	local pkg_manager powertools

	cat <<EOF >/tmp/repo.config
[centos-7]
name=centos-7
baseurl=http://mirror.centos.org/centos/7/os/${ARCH}
gpgcheck=0

[centos-8]
name=centos-8
baseurl=http://mirror.centos.org/centos/8-stream/BaseOS/${ARCH}/os
gpgcheck=0

[centos-9]
name=centos-9
baseurl=http://mirror.stream.centos.org/9-stream/BaseOS/${ARCH}/os
gpgcheck=0

[fedora-${RELEASE}]
name=fedora-${RELEASE}
baseurl=https://dl.fedoraproject.org/pub/archive/fedora/linux/releases/${RELEASE}/Everything/${ARCH}/os
gpgcheck=0

[opensuse-${RELEASE}]
name=opensuse-${RELEASE}
baseurl=http://download.opensuse.org/distribution/leap/${RELEASE}/repo/oss
gpgcheck=0
EOF

	pkg_manager=dnf
	powertools=0

	case "${DIST}" in
		centos-7)
			pkg_manager=yum
			;;
		centos-8)
			powertools=1
			;;
	esac

	# Install the base system
	mkdir -p "${BASEDIR}"
	dnf --config=/tmp/repo.config --assumeyes --nogpgcheck \
		--releasever="${RELEASE}" \
		--disablerepo=* --enablerepo="${DIST}" \
		--installroot="${BASEDIR}" install "${pkg_manager}"

	# We need to reinstall the base system because the original installation
	# put the RPM database in ~/.rpmdb
	${SCHROOT} "${pkg_manager}" --releasever="${RELEASE}" --assumeyes \
			   --nogpgcheck install "${pkg_manager}"

	# Install the base packages
	${SCHROOT} "${pkg_manager}" --assumeyes install epel-release || true
	for package in "${RPM_INCLUDE[@]}" ; do
		${SCHROOT} "${pkg_manager}" --assumeyes install "${package}" || true
	done

	# Install the additional packages
	if [ "${BASE}" -eq 0 ] ; then
		if [ ${powertools} -eq 1 ] ; then
			${SCHROOT} dnf config-manager --set-enabled powertools
		fi
		for package in "${RPM_PACKAGES[@]}" ; do
			${SCHROOT} "${pkg_manager}" --assumeyes install "${package}" || true
		done
	fi

	# Clean the cache
	${SCHROOT} "${pkg_manager}" clean all

	# TODO: Enable the debuginfo repos
}


# -----------------------------------------------------------------------------
# Usage

function usage()
{
	cat <<EOF
Usage: create-chroot [-a ARCH] [-b] [-d] [-f] [-h] [-k] [-n] DIST [NAME]

Create a chroot for kernel package builds.

Positional arguments:
  DIST  A recognized distribution, like bionic, stretch, fedora-26, ...
  NAME  The name of the chroot, defaults to <DIST>-<ARCH> if not specified.

Optional arguments:
  -a, --arch ARCH     Architecture of the chroot (defaults to the host
                      architecture).
  -b, --base          Create a base chroot without additional packages.
  -d, --debug         Enable debugging (set -x).
  -f, --force         Force the recreation of an existing chroot.
  -h, --help          Show this help text.
  -k, --keep          Keep the chroot and config file after a build failure.
  -n, --no-check-gpg  Don't check GPG signatures of retrieved Release files.

EOF
}


# -----------------------------------------------------------------------------
# Main entry point

ARCH=
BASE=0
FORCE=0
DIST=
KEEP=0
NAME=
NO_CHECK_GPG=0

while [ ${#} -gt 0 ] ; do
	case ${1} in
		-a|--arch)
			ARCH="${2}"
			shift
			;;
		-b|--base)
			BASE=1
			;;
		-d|--debug)
			set -x
			;;
		-f|--force)
			FORCE=1
			;;
		-h|--help)
			usage
			exit
			;;
		-k|--keep)
			KEEP=1
			;;
		-n|--no-check-gpg)
			NO_CHECK_GPG=1
			;;
		-*)
			echo "Error: Unexpected option: ${1}" >&2
			exit 2
			;;
		*)
			if [ -z "${DIST}" ] ; then
				DIST="${1}"
			elif [ -z "${NAME}" ] ; then
				NAME="${1}"
			else
				echo "Error: Unexpected argument: ${1}" >&2
				exit 2
			fi
			;;
	esac
	shift
done

if [ -z "${DIST}" ] ; then
	usage
	exit 2
fi

case "${DIST}" in
	fedora-*|centos-*|opensuse-*)
		BASE_NAME=${DIST/-/}
		BASE_DIST=fedora
		VENDOR=${DIST%%-*}
		if [ -z "${ARCH}" ] ; then
			ARCH=x86_64
		fi
		;;
	debian-*|ubuntu-*)
		BASE_NAME=${DIST#*-}
		BASE_DIST=debian
		VENDOR=${DIST%%-*}
		;;
	stretch|buster|bullseye|bookworm|sid)
		BASE_NAME=${DIST}
		BASE_DIST=debian
		VENDOR=debian
		;;
	*)
		BASE_NAME=${DIST}
		BASE_DIST=debian
		VENDOR=ubuntu
		;;
esac

if [ "${BASE_DIST}" = "debian" ] ; then
	echo "Deprecated for Debian/Ubuntu! Use 'run-chroot'."
	exit 1
fi

RELEASE=${DIST#*-}

if [ -z "${ARCH}" ] ; then
	ARCH=amd64
fi

if [ -z "${NAME}" ] ; then
	NAME="${BASE_NAME}-${ARCH}"
fi

SCHROOT="schroot -c ${NAME} --"

print_vars DIST VENDOR RELEASE ARCH NAME

# -----------------------------------------------------------------------------
# Verify that we're root

if [ "$(id -u)" -ne 0 ] ; then
	echo "Error: This script needs to be run as root" >&2
	exit 1
fi

# -----------------------------------------------------------------------------
# Sanity checks

# Check if the chroot is currently in use
if mount | grep -E -q "/run/schroot/mount/${NAME}-[0-9a-f]{8}-" ; then
	echo "Error: The chroot is currently mounted and in use" >&2
	exit 1
fi

BASEDIR=/var/lib/schroot/chroots/${NAME}

# Verify the chroot directory
if ! [ -d "${BASEDIR%/*}" ] ; then
	echo "Error: No such directory: ${BASEDIR%/*}"
	exit 1
fi

# Check if the chroot directory exists already
if [ -d "${BASEDIR}" ] ; then
	if [ "${FORCE}" -eq 0 ] ; then
		echo "Error: Chroot directory exists already" >&2
		echo "       Use -f, --force to recreate it" >&2
		exit 1
	else
		rm -rf "${BASEDIR}"
	fi
fi

trap out EXIT INT HUP TERM

# -----------------------------------------------------------------------------
# Add a config file to /etc/schroot/chroot.d/

cat <<EOF >"/etc/schroot/chroot.d/${NAME}"
[${NAME}]
type=directory
directory=${BASEDIR}
root-users=${SUDO_USER}
preserve-environment=true
EOF

# -----------------------------------------------------------------------------
# Create the chroot

"${BASE_DIST}_create_chroot"

# -----------------------------------------------------------------------------
# Add a sudo user to the chroot

sudoer="${BASEDIR}/etc/sudoers.d/${SUDO_USER}"
cat <<EOF >"${sudoer}"
${SUDO_USER} ALL = NOPASSWD: ALL
EOF
chmod 440 "${sudoer}"

# -----------------------------------------------------------------------------
# Create /etc/hosts

cat <<EOF >"${BASEDIR}"/etc/hosts
127.0.0.1  localhost
127.0.1.1  $(hostname)
EOF