userns.sh

#!/bin/bash

if [ ! -f /usr/bin/uidmapshift ]; then
	wget https://bazaar.launchpad.net/~serge-hallyn/+junk/nsexec/download/head:/uidmapshift.c-20121030152620-2zy9rkac9y6htoia-8/uidmapshift.c
	gcc -o uidmapshift uidmapshift.c
	sudo mv uidmapshift /usr/bin/uidmapshift
	rm -f uidmapshift.c
fi

uid=$(grep $USER /etc/subuid | cut -d : -f 2)
gid=$(grep $USER /etc/subgid | cut -d : -f 2)
range=$(grep $USER /etc/subuid | cut -d : -f 3)

NOCOLOR="\033[0m"
OKCOLOR="\033[0;32m"

ORIGINAL="original"
CLONE="clone"
LXCPATH="$HOME/lxcpath"

lxc_conf() {
	mkdir -p $LXCPATH

	cat > $LXCPATH/lxc.conf << EOF
lxc.network.type = veth
lxc.network.link = lxcbr0
lxc.network.flags = up

lxc.id_map = u 0 $uid $range
lxc.id_map = g 0 $gid $range
EOF
}

start_attach_stop() {
	CONTAINER=$1

	echo -e "$OKCOLOR\tStarting/Attaching/Stopping to $CONTAINER $NOCOLOR"
	sudo lxc-start -d -n $CONTAINER -P $LXCPATH -l debug -o $CONTAINER.log
	sudo lxc-attach -n $CONTAINER -P $LXCPATH -- hostname
	sudo lxc-stop -n $CONTAINER -P $LXCPATH
}

destroy() {
	echo -e "$OKCOLOR\tDestroying $ORIGINAL and $CLONE $NOCOLOR"

	sudo lxc-destroy -n $CLONE -P $LXCPATH
	sudo lxc-destroy -n $ORIGINAL -P $LXCPATH
	sudo rm -f $ORIGINAL.log $CLONE.log
	sudo rm -rf $LXCPATH
}

uidshift() {
	CONTAINER=$1
	DIRECTORY=$2

	sudo uidmapshift -u $LXCPATH/$CONTAINER/$DIRECTORY 0 $uid $range
	sudo uidmapshift -g $LXCPATH/$CONTAINER/$DIRECTORY 0 $gid $range
}

original() {
	BACKEND=$1
	echo -e "$OKCOLOR\tCreating $ORIGINAL with $BACKEND $NOCOLOR"

	lxc_conf

	sudo lxc-create -q -B $BACKEND -t ubuntu -n $ORIGINAL -P $LXCPATH -f $LXCPATH/lxc.conf
	if [ $? -eq 0 ]; then
		uidshift $ORIGINAL rootfs

		start_attach_stop $ORIGINAL
	fi
}

clone() {
	BACKEND=$1
	echo -e "$OKCOLOR\tCloning $CLONE with $BACKEND $NOCOLOR"

	sudo lxc-clone -s -B $BACKEND -p $LXCPATH $ORIGINAL $CLONE > /dev/null
	if [ $? -eq 0 ]; then
		uidshift $CLONE rootfs
		if [ $BACKEND == "overlayfs" ]; then
			uidshift $CLONE delta0
		fi

		start_attach_stop $CLONE
	fi
}

original dir
# this will require a patched kernel
clone overlayfs
destroy

original btrfs
clone btrfs
destroy