#!/bin/bash
# Creates a new virtual machine from the given stage3 tarball

DOMNAME="$1"
STAGE_TBZ="$2"
VMNAME=$(echo "${DOMNAME}" | tr '[:upper:]' '[:lower:]')
VM_FQDN="${VMNAME}.$(hostname -d)"

if [[ -z $STAGE_TBZ || -z $VMNAME ]]; then
	echo "Usage: $(basename $0) <vmname> <stage3-tarball>" >&2
	exit 2
fi

: ${VG:=vmachines}
: ${POOL:=LVM}
: ${DOMXML_TMPL:=/etc/libvirt/qemu/_template.xml}
: ${MOUNTPOINT:=/mnt/new_vmachine}
: ${PORTAGE_PROFILE:="default/linux/amd64/13.0"}

set -e

PORTDIR=$(portageq envvar PORTDIR)
DISTDIR=$(portageq envvar DISTDIR)
PKGDIR=$(portageq envvar PKGDIR)

if lvdisplay ${VG}/${VMNAME} >/dev/null 2>&1; then
	echo "ERROR: Logical volume ${VMNAME} already exists in group ${VG}" >&2
	exit 1
fi

echo "Creating storage volume..."
virsh -c qemu:///system vol-create-as ${POOL} ${VMNAME} 2G

echo "Creating LVM volumes..."
pvcreate /dev/${VG}/${VMNAME}
vgcreate ${VMNAME} /dev/${VG}/${VMNAME}
lvcreate -nhome -L200M ${VMNAME}
lvcreate -nvar -L400M ${VMNAME}
lvcreate -nroot -l100%FREE ${VMNAME}

echo "Creating XFS filesystems..."
for fs in root home var; do
	mkfs.xfs -L$fs -q /dev/${VMNAME}/$fs
done

echo "Mounting filesystems..."
[[ ! -d "${MOUNTPOINT}" ]] && mkdir -p "${MOUNTPOINT}"
mount /dev/${VMNAME}/root "${MOUNTPOINT}"
for fs in home var; do
	mkdir "${MOUNTPOINT}"/$fs
	mount /dev/${VMNAME}/$fs "${MOUNTPOINT}"/$fs
done
mkdir "${MOUNTPOINT}"/run
mount -t tmpfs tmpfs "${MOUNTPOINT}"/run

echo "Extracting stage tarball..."
tar -xjpf "${STAGE_TBZ}" -C "${MOUNTPOINT}"

cp -L /etc/resolv.conf "${MOUNTPOINT}/etc/resolv.conf"

echo "Installing critical packages..."
# Installing packages must be done in a chroot instead of using the $ROOT
# Portage environment variable because several ebuilds use enewuser/enewgroup
# to create system users, which creates the user on the host system, not the
# target system. See Gentoo bug #53269 for details on the problem.

mkdir "${MOUNTPOINT}"/usr/portage
mount -obind "${PORTDIR}" "${MOUNTPOINT}"/usr/portage
mount -obind "${DISTDIR}" "${MOUNTPOINT}"/usr/portage/distfiles
mount -obind "${PKGDIR}" "${MOUNTPOINT}"/usr/portage/packages
mount -t tmpfs tmpfs "${MOUNTPOINT}"/tmp
mount -t proc proc "${MOUNTPOINT}"/proc
mount -t sysfs sysfs "${MOUNTPOINT}"/sys

cat <<EOF > "${MOUNTPOINT}"/build-base.sh
#!/bin/bash

set -e

export EMERGE_DEFAULT_OPTS="--binpkg-respect-use=y"
export FEATURES="-news"

env-update
USE=-thin emerge -jkv xfsprogs nfs-utils lvm2
rc-update add lvm boot
EOF
chmod u+x "${MOUNTPOINT}"/build-base.sh
chroot "${MOUNTPOINT}" /build-base.sh
rm "${MOUNTPOINT}"/build-base.sh

echo "Setting hostname..."
sed -i "s/localhost/${VMNAME}/" "${MOUNTPOINT}"/etc/conf.d/hostname

echo "Configuring network..."
echo 'config_eth0="dhcp"' > "${MOUNTPOINT}"/etc/conf.d/net
echo 'dhcpcd_eth0="-q"' >> "${MOUNTPOINT}"/etc/conf.d/net
ln -s net.lo "${MOUNTPOINT}"/etc/init.d/net.eth0
ln -s /etc/init.d/net.eth0 "${MOUNTPOINT}"/etc/runlevels/default/
ln -s /etc/init.d/sshd "${MOUNTPOINT}"/etc/runlevels/default/

echo "Configuring fstab..."
cat << EOF > "${MOUNTPOINT}"/etc/fstab
LABEL=root		/		xfs		noatime		0 1
LABEL=var		/var		xfs		noatime		0 2
LABEL=home		/home		xfs		noatime		0 2
tmpfs			/tmp		tmpfs		defaults	0 0
EOF

echo "Creating read-only root filesystem compatibility symlinks..."
rm -f "${MOUNTPOINT}"/etc/{resolv,ntp}.conf
rm -f "${MOUNTPOINT}"/etc/mtab
ln -s /proc/mounts "${MOUNTPOINT}"/etc/mtab
ln -s /run/resolv.conf "${MOUNTPOINT}"/etc/resolv.conf
ln -s /run/ntp.conf "${MOUNTPOINT}"/etc/ntp.conf

echo "Blanking root password..."
sed -i 's/^root:.*/root::0:0:::::/' "${MOUNTPOINT}"/etc/shadow

echo "Enabling serial console..."
sed -i 's/#s0/s0/' "${MOUNTPOINT}"/etc/inittab

echo "Cleaning up..."
umount "${MOUNTPOINT}"/usr/portage/{packages,distfiles,}
rmdir "${MOUNTPOINT}"/usr/portage
umount "${MOUNTPOINT}"/{tmp,proc,sys,run,var,home,}
vgchange -an ${VMNAME}

echo "Creating libvirt domain..."
virsh -c qemu:///system define <(m4 -P -DNAME="${DOMNAME}" "${DOMXML_TMPL}")
echo "Starting virtual machine..."
virsh -c qemu:///system start ${DOMNAME}