snapshot-lxc

#!/bin/bash
set -eu -o pipefail
safe_source () { [[ ! -z ${1:-} ]] && source $1; _dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"; _sdir=$(dirname "$(readlink -f "$0")"); }; safe_source


safe_source $_sdir/dcs-tools/aktos-bash-lib/all.sh

rm_folder(){
	if is_btrfs $1; then
		btrfs sub del $1
	else
		rm -r $1
	fi
}

cp_folder(){
	local target
	[[ -d $2 ]] && target=$2 || target=$(dirname $2)
	if is_btrfs $1 && is_btrfs $target; then
		btrfs sub snap $1 $2
	else
		cp -al $1 $2
	fi
}


# show help
show_help(){
    cat <<HELP

    Usage:

    	$(basename $0) ...options


    Options

        --src /path/to/subvolume      : Subvolume source
        --name your-container-name    : Container name

        --delete your-container-name  : Delete the container
        --keep-ssh-keys               : Do not regenerate SSH keys
        --config                      : Open config file after creating the container
        --list	                      : List currently assigned IP's

HELP
    exit
}

die(){
    echo_red "$1"
    show_help
    exit 1
}

# Parse command line arguments
# ---------------------------
# Initialize parameters
new_keys=true
NAME=
SUBVOL=
delete_vm=false
open_config=false
list=false
# ---------------------------
args=("$@")
_count=1
while :; do
    key="${1:-}"
    case $key in
        -h|-\?|--help|'')
            show_help    # Display a usage synopsis.
            exit
            ;;
        # --------------------------------------------------------
        --name) shift
            if [[ ! -z ${1:-} ]]; then
                NAME=$1
                shift
            fi
            ;;

        --src) shift
            if [[ ! -z ${1:-} ]]; then
                SUBVOL=$1
                shift
            fi
            ;;
        --keep-ssh-keys) shift
            new_keys=false
            ;;
        --config) shift
            open_config=true
            ;;
        --list) shift
            list=true
            ;;
        --delete) shift
            delete_vm=true
            if [[ ! -z ${1:-} ]]; then
                NAME=$1
                shift
            fi
            ;;
        # --------------------------------------------------------
        -*) # Handle unrecognized options
            echo
            echo "Unknown option: $1"
            show_help
            exit 1
            ;;
        *)  # generate the positional arguments
            declare _arg$((_count++))="$1"
            shift
    esac
    [[ -z ${1:-} ]] && break
done; set -- "${args[@]}"
# use $_arg1 in place of $1, $_arg2 in place of $2 and so on, "$@" is intact

lxc_major=$(lxc-ls --version | cut -d. -f1)

if [[ $list = true ]]; then
    [[ $(whoami) = "root" ]] || { sudo $0 "$@"; exit 0; }
    echo "List of containers:"
    echo "------------------"
    set +e
    for vm_conf in /var/lib/lxc/*/config; do
        [[ -f $vm_conf ]] || continue
        vm_name=$(basename $(dirname $vm_conf))
        if [[ "$lxc_major" == "2" ]]; then
        	ip=$(cat $vm_conf | egrep "^lxc\.network\.ipv4\s*=" | cut -d "=" -f 2)
        elif [[ "$lxc_major" == "3" ]] || [[ "$lxc_major" == "4" ]] || [[ "$lxc_major" == "5" ]]; then
        	ip=$(cat $vm_conf | egrep "^lxc\.net.*\.ipv4.address\s*=" | cut -d "=" -f 2)
        fi
    	echo -e "$vm_name\t\t: $ip"
    done
    exit 0
fi


# Check parameters
[[ -z $NAME ]] && die "Name of VM is required."
[[ $delete_vm = false ]] && [[ -z $SUBVOL ]] && die "Source directory (rootfs) is required"

# All checks are done, run as root.
[[ $(whoami) = "root" ]] || { sudo $0 "$@"; exit 0; }

if ! is_btrfs /var/lib/lxc; then
    echo_info "This is a non-BTRFS file system."
else
    echo_info "BTRFS file system"
fi

GUEST_ROOT="/var/lib/lxc/$NAME/rootfs"

if [[ $delete_vm = true ]]; then
    read -p "Press enter to stop and delete LXC container: $NAME"
    set +e
    if [[ $(lxc-info -n $NAME | awk '$1 ~ /State/ {print $2}') == "RUNNING" ]]; then
        lxc-stop -n $NAME
    fi
    rm_folder $GUEST_ROOT
    rm -r $(dirname $GUEST_ROOT)
    echo_green "Removed $NAME"
	exit
fi

START_TIME=$SECONDS

echo "creating the container directory: $NAME"
mkdir -p $(dirname $GUEST_ROOT)

echo "creating a writable snapshot of given subvolume"
cp_folder $SUBVOL $GUEST_ROOT

_param=
[[ $new_keys = false ]] && _param="--skip-ssh-keys"

$_sdir/dcs-tools/give-new-id \
    --hostname $NAME \
    --root-dir $GUEST_ROOT \
    $_param

if [[ -f $GUEST_ROOT/etc/fstab ]]; then
    echo "emptying the /etc/fstab file"
    mv $GUEST_ROOT/etc/fstab $GUEST_ROOT/etc/fstab.real
    touch $GUEST_ROOT/etc/fstab
else
    echo "No /etc/fstab file found, skipping removal."
fi

echo "remove the LXC specific entry from GUEST/etc/network/interfaces file"
IFACE_FILE=$GUEST_ROOT/etc/network/interfaces
mv $IFACE_FILE $IFACE_FILE.real

awk '/lxc-bridge/ {do_print=0}
     do_print==1 {print}
     NF==0 {do_print=1}' $IFACE_FILE.real > $IFACE_FILE


echo "creating the config file"

if [[ "$lxc_major" == "2" ]]; then
	cat <<- CONFIG2 > $(dirname $GUEST_ROOT)/config

	# Template used to create this container: /usr/share/lxc/templates/lxc-download
	# Parameters passed to the template:
	# Template script checksum (SHA-1): 740c51206e35463362b735e68b867876048a8baf
	# For additional config options, please look at lxc.container.conf(5)
	# Uncomment the following line to support nesting containers:
	#lxc.include = /usr/share/lxc/config/nesting.conf
	# (Be aware this has security implications)
	# Distribution configuration
	lxc.include = /usr/share/lxc/config/debian.common.conf
	lxc.arch = $(uname -m)

	# Container specific configuration
	lxc.rootfs = /var/lib/lxc/$NAME/rootfs
	lxc.rootfs.backend = dir
	lxc.utsname = $NAME

	# Network configuration
	lxc.network.type = veth
	lxc.network.link = lxc-bridge
	lxc.network.flags = up
	#lxc.network.ipv4.gateway = 10.0.8.1
	#lxc.network.ipv4 = 10.0.8.8

	# External mounts
	#lxc.mount.entry = /path/to/host/folder     path/to/folder/in/container     none    bind    0 0
CONFIG2
elif [[ "$lxc_major" == "3" ]] || [[ "$lxc_major" == "4" ]] || [[ "$lxc_major" == "5" ]]; then
	cat <<- CONFIG3 > $(dirname $GUEST_ROOT)/config
	# Template used to create this container: /usr/share/lxc/templates/lxc-download
	# Parameters passed to the template:
	# Template script checksum (SHA-1): 740c51206e35463362b735e68b867876048a8baf
	# For additional config options, please look at lxc.container.conf(5)

	# Uncomment the following line to support nesting containers:
	#lxc.include = /usr/share/lxc/config/nesting.conf
	# (Be aware this has security implications)

	# Distribution configuration
	lxc.include = /usr/share/lxc/config/debian.common.conf
	lxc.arch = $(uname -m)

	# Container specific configuration
	lxc.rootfs.path = /var/lib/lxc/$NAME/rootfs
	lxc.uts.name = $NAME

	# Network configuration
	lxc.net.0.type = veth
	lxc.net.0.link = lxc-bridge
	lxc.net.0.flags = up
	#lxc.net.0.ipv4.gateway = 10.0.8.1
	#lxc.net.0.ipv4.address = 10.0.8.8

	# External mounts
	#lxc.mount.entry = /path/to/host/folder     path/to/folder/in/container     none    bind    0 0

CONFIG3
else
	echo_red "Unknown lxc version: $lxc_major"
	echo_red "No configuration file is generated."
    echo_yellow "For config options, please look at lxc.container.conf(5)"
fi

echo_green "done in $(($SECONDS - $START_TIME)) seconds..."

cat <<USAGE

to run the vm:

	sudo lxc-start -n $NAME

to attach the root console:

	sudo lxc-attach -n $NAME

to run GUI applications, make SSH with X forwarding:

    ssh -X youruser@container-ip

---------------------------------------------------
                  NOTE:

* Configure network in /var/lib/lxc/$NAME/config

---------------------------------------------------
USAGE

# Open configuration file
[[ $open_config = true ]] && nano /var/lib/lxc/$NAME/config