File vm-snapshot-disk of Package virt-utils
#!/bin/bash
#============================================================================
# vm-snapshot-disk
#
# Version = 0.4.0
# Date = 2010-02-12
#
# Copyright - Ron Terry
# License - GPL
#
# Maintainer(s) = Ron Terry - roncterry (at) gmail (dot) com
#
# The latest version can be found at:
#
# http://pronetworkconsulting.com/linux/scripts/virt-tools.html
#
# Description:
# This script creates and manages snapshots of qcow2 virtual disks.
#
# Individual snapshots and snapshot trees are supported. The names
# of the snapshots in the snapshot tree are stored in the actual
# filenames of the snapshots themselves. Descriptions of each
# snapshot can be provided and will be stored in a file named
# .$DISK.snap_descriptions
#
# The following operations can be performed:
#
# create -creates a new snapshot from the current position in the
# snapshot tree
# branch -creates a new branch of the snapshot tree from the
# specified snapshot
# revert -reverts to the specified snapshot and deletes all linked
# snapshots from the snapshot tree
# remove -removes all snapshosts and snapshot descriptions from
# the disk image
# list -list all snapshots and their descriptions
# help -displays the description and usage
#
#============================================================================
###################################################################################
# Read config files and set variables
###################################################################################
if which qemu-img > /dev/null 2>&1
then
QEMU_IMG_CMD=qemu-img
elif which qemu-img-xen > /dev/null 2>&1
then
QEMU_IMG_CMD=qemu-img-xen
fi
###################################################################################
# Script Functions
###################################################################################
########## Function: description ###############################
description() {
echo "
================================================================================
Description:
This script creates and manages snapshots of qcow2 virtual disks
Individual snapshots and snapshot trees are supported. The names
of the snapshots in the snapshot tree are stored in the actual
filenames of the snapshots themselves. Descriptions of each
snapshot can be provided and will be stored in a file named
.\$DISK.snap_descriptions
The following operations can be performed:
create -creates a new snapshot from the current position in the
snapshot tree
branch -creates a new branch of the snapshot tree from the
specified snapshot
revert -reverts to the specified snapshot and deletes all linked
snapshots from the snapshot tree
remove -removes all snapshosts and snapshot descriptions from
the disk image
list -list all snapshots and their descriptions
help -displays the description and usage
================================================================================
"
# delete -deletes the specified snapshot and all linked snapshots
# from the snapshot tree
}
########## Function: usage ###########################################
usage() {
echo
echo "Usage: vm-snapshot-disk [create|branch|revert|remove|list|help] options"
echo
echo "Examples:"
echo " vm-snapshot-disk create disk=<DISK_NAME> [snapname=<SNAPSHOT_NAME> description=\"<SNAPSHOT_DESCRIPTION>\"]"
echo " vm-snapshot-disk branch disk=<DISK_NAME> snapname=<SNAPSHOT_NAME> [description=\"<SNAPSHOT_DESCRIPTION>\"]"
echo " vm-snapshot-disk revert disk=<DISK_NAME> snapname=<SNAPSHOT_NAME>"
echo " vm-snapshot-disk remove disk=<DISK_NAME>"
echo " vm-snapshot-disk list disk=<DISK_NAME>"
echo " vm-snapshot-disk help"
echo
}
########## Function: get_options #####################################
get_options() {
case "$1" in
#create|branch|revert|delete|help)
create|branch|revert|remove|list)
MODE="$1"
;;
help|-h|--help)
MODE=help
;;
*)
echo
echo "ERROR: You must provide a valid mode!"
usage
exit 1
;;
esac
if echo "$*" | grep -q "disk="
then
local DISK_IMAGE_FULL=`echo "$*" | grep -o "disk=.*" | cut -d '=' -f 2 | cut -d ' ' -f 1`
fi
if echo $* | grep -q "snapname="
then
SNAPSHOT_NAME=`echo $* | grep -o "snapname=.*" | cut -d '=' -f 2 | cut -d ' ' -f 1`
fi
if echo $* | grep -q "description="
then
#SNAPSHOT_DESCR=`echo $* | grep -o "description=.*" | cut -d '=' -f 2 | cut -d ' ' -f 1`
SNAPSHOT_DESCR=`echo $* | grep -o "description=.*" | cut -d '=' -f 2`
fi
if [ -z "$DISK_IMAGE_FULL" ]
then
case "$MODE" in
help|-h)
MODE=help
description
usage
exit 99
;;
*)
echo
echo "ERROR: You must supply a disk image!"
usage
exit 1
esac
else
DISK_IMAGE=`get_file_name $DISK_IMAGE_FULL`
DISK_PATH=`get_file_path $DISK_IMAGE_FULL`
fi
}
########## Function: get_file_path ######################################
get_file_path() {
if [ -z $1 ]
then
echo "Usage: get_file_path <absolute|relative_path_to_file>"
return 1
else
local FILE="$1"
fi
local DIR_COUNT=`echo $FILE|grep -o "/"|wc -l`
((DIR_COUNT++))
local FILE_NAME=`echo $FILE|cut -d "/" -f $DIR_COUNT`
local FILE_DIR=`echo $FILE|sed "s/$FILE_NAME$//g"`
echo $FILE_DIR
}
########## Function: get_file_name ######################################
get_file_name() {
if [ -z $1 ]
then
echo "Usage: get_file_name <absolute|relative_path_to_file>"
return 1
else
local FILE="$1"
fi
local DIR_COUNT=`echo $FILE|grep -o "/"|wc -l`
((DIR_COUNT++))
local FILE_NAME=`echo $FILE|cut -d "/" -f $DIR_COUNT`
local FILE_DIR=`echo $FILE|sed "s/$FILE_NAME$//g"`
echo $FILE_NAME
}
########## Function: test_disk ###########################################
test_disk() {
local DISK="$1"
if ! [ -e "$DISK" ]
then
echo
echo "ERROR: The specified disk \"$DISK\" does not exist!"
echo
exit 2
fi
if ! ($QEMU_IMG_CMD info $DISK | grep "file format" | cut -d ' ' -f 3 | grep -q qcow2) 2> /dev/null
then
echo
echo "ERROR: The specified disk \"$DISK\" does not appear to be of type qcow2"
echo " You cannot snpashot this disk!"
exit 3
fi
}
########## Function: get_backing_disk #####################################
get_backing_disk() {
"$QEMU_IMG_CMD" info "$1" | grep "backing file" | cut -d : -f 3 | sed 's/^ *//g' | sed 's/)//g'
}
########## Function: find_unused_snap_name ################################
find_unused_snap_name() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
if [ -z "$SNAPNAME" ]
then
#echo "Finding and unused snap name"
SNAMECOUNT=1
SNAPNAME=snap"$SNAMECOUNT"
until ! ls "$DISK".* | grep -q snap"$SNAMECOUNT"
do
((SNAMECOUNT++))
SNAPNAME=snap"$SNAMECOUNT"
done
fi
echo "$SNAPNAME"
}
########## Function: create_first_snapshot ################################
create_first_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
local BDISK="$DISK".base
mv "$DISK" "$BDISK"
SNAPNAME=`find_unused_snap_name "$DISK" "$SNAPNAME" "$SNAP_DESCR"`
echo " Creating new snapshot: $BDISK.$SNAPNAME"
echo "*****************************************************************"
ln "$BDISK" "$BDISK"."$SNAPNAME"
chmod a-w "$BDISK"
chmod a-w "$BDISK"."$SNAPNAME"
"$QEMU_IMG_CMD" create -f qcow2 -b "$BDISK" "$BDISK"."$SNAPNAME"._working
ln -s "$BDISK"."$SNAPNAME"._working "$DISK"
# add snapshot description
echo `echo "$BDISK.$SNAPNAME" | sed 's/\./_/g' | sed 's/__working//g'`"='$SNAP_DESCR'" >> ."$DISK".snap_descriptions
}
########## Function: create_additional_snapshot ###########################
create_additional_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
local BDISK=`ls -l "$DISK" |cut -d ">" -f 2 | sed 's/^ *//g'`
rm -f "$DISK"
SNAPNAME=`find_unused_snap_name "$DISK" "$SNAPNAME" "$SNAP_DESCR"`
BASE_BDISK="`echo "$BDISK" | sed 's/\._working//g'`"
echo " Creating new snapshot: $BASE_BDISK.$SNAPNAME"
echo "*****************************************************************"
mv "$BDISK" "$BASE_BDISK"."$SNAPNAME"
chmod a-w "$BASE_BDISK"."$SNAPNAME"
"$QEMU_IMG_CMD" create -f qcow2 -b "$BASE_BDISK"."$SNAPNAME" "$BASE_BDISK"."$SNAPNAME"._working
ln -s "$BASE_BDISK"."$SNAPNAME"._working "$DISK"
# add snapshot description
echo `echo "$BDISK.$SNAPNAME" | sed 's/\./_/g' | sed 's/__working//g'`"='$SNAP_DESCR'" >> ."$DISK".snap_descriptions
}
########## Function: create_snapshot ######################################
create_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
#echo "Testing for base disk image file"
if ! [ -e "$DISK".base ]
then
create_first_snapshot "$DISK" "$SNAPNAME" "$SNAP_DESCR"
#return
elif [ -L "$DISK" ]
then
create_additional_snapshot "$DISK" "$SNAPNAME" "$SNAP_DESCR"
#return
fi
}
########## Function: branch_at_snapshot #####################################
branch_at_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
if [ -z "$SNAPNAME" ]
then
echo
echo "ERROR: You must supply a snapshot name to branch from!"
echo
exit 4
fi
if ! ls "$DISK".* | grep -q "$SNAPNAME$"
then
echo
echo "ERROR: The specified snapshot \"$SNAPNAME\" does not appear to exist!"
echo
exit 5
fi
local SNAP_POINT=`ls "$DISK".* | grep "$SNAPNAME$"`
#echo "Finding and unused snap name"
local SNAMECOUNT=1
until ! ls "$DISK".* | grep -q "$SNAPNAME"-"$SNAMECOUNT"$
do
((SNAMECOUNT++))
done
SUB_SNAPNAME="$SNAPNAME"-"$SNAMECOUNT"
echo "*****************************************************************"
echo " Branching from snapshot: $SNAP_POINT"
rm -f "$DISK"
rm -f "$DISK".*._working
#ln -s "$SNAP_POINT" "$DISK"
#create_snapshot "$DISK" "$SUB_SNAPNAME" "$SNAP_DESCR"
"$QEMU_IMG_CMD" create -f qcow2 -b "$SNAP_POINT" "$SNAP_POINT"."$SUB_SNAPNAME"._working
ln -s "$SNAP_POINT"."$SUB_SNAPNAME"._working "$DISK"
chmod a-w "$SNAP_POINT"
}
########## Function: revert_to_snapshot #####################################
revert_to_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
if [ -z "$SNAPNAME" ]
then
echo
echo "ERROR: You must supply a snapshot name to revert to!"
echo
exit 4
fi
if ! ls "$DISK".* | grep -q "$SNAPNAME$"
then
echo
echo "ERROR: The specified snapshot \"$SNAPNAME\" does not appear to exist!"
echo
exit 5
fi
local SNAP_POINT=`ls "$DISK".* | grep "$SNAPNAME$"`
echo "*****************************************************************"
echo " Reverting to snapshot: $SNAP_POINT"
echo "*****************************************************************"
rm -f "$DISK"
rm -f "$DISK".*._working
rm -f "$SNAP_POINT".*
"$QEMU_IMG_CMD" create -f qcow2 -b "$SNAP_POINT" "$SNAP_POINT"._working
ln -s "$SNAP_POINT"._working "$DISK"
chmod a-w "$SNAP_POINT"
# remove snapshot description
sed -i "/$SNAP_POINT\..*/d" ."$DISK".snap_descriptions
}
########## Function: remove_snapshot #####################################
remove_snapshots() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
#echo "Testing for base disk image file"
if ! [ -e "$DISK".base ]
then
echo "$DISK doesn't appear to have any snapshots"
else
echo "*****************************************************************"
echo " Removing all snapshots from: $DISK"
echo "*****************************************************************"
rm -f "$DISK"
chmod u+w "$DISK".base.*
rm -r "$DISK".base.*
# remove snapshot description
rm -f ."$DISK".snap_descriptions
mv "$DISK".base "$DISK"
fi
}
########## Function: list_snapshots ######################################
list_snapshots() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESCR="$3"
#echo "Testing for base disk image file"
if ! [ -e "$DISK".base ]
then
echo "$DISK doesn't appear to have any snapshots"
else
for SNAP in `ls "$DISK".base.*`
do
#echo "SNAP=$SNAP";read
if ! echo "$SNAP" | grep -q "_working"
then
local DOT_COUNT=`echo $SNAP | grep -o \\\. | wc -l`
((DOT_COUNT++))
local SNAP_NAME=`echo "$SNAP" | cut -d \. -f "$DOT_COUNT"`
local SNAP_ENTRY=`echo $SNAP | sed 's/\./_/g'`
echo -n "$SNAP_NAME = ";grep "$SNAP_ENTRY=" ."$DISK".snap_descriptions | cut -d '=' -f 2
fi
done
fi
}
########## Function: delete_snapshot #####################################
# Disabled until I can figure out how to 'merge' cow snapshots
delete_snapshot() {
local DISK="$1"
local SNAPNAME="$2"
local SNAP_DESC="$3"
if [ -z "$SNAPNAME" ]
then
echo
echo "ERROR: You must supply a snapshot name to delete!"
echo
exit 4
fi
if ! ls "$DISK".* | grep -q "$SNAPNAME$"
then
echo
echo "ERROR: The specified snapshot \"$SNAPNAME\" does not appear to exist!"
echo
exit 5
fi
if [ "$DISK.$SNAPNAME" = "$DISK.base" ]
then
echo
echo "ERROR: You cannot delete the base image!"
echo
exit 6
fi
local SNAP_DEL=`ls "$DISK".* | grep "$SNAPNAME$"`
local SNAP_POINT=`echo $SNAP_DEL | sed "s/\.$SNAPNAME$//g"`
if [ "$SNAP_POINT" = "$DISK.base" ]
then
echo > /dev/null
#echo "Guess its the base"
#continue
elif ls "$SNAP_POINT".* > /dev/null 2>&1
then
#echo "SNAP_POINT=$SNAP_POINT, looking for end of snap train"
local SNAP_POINT_OPTIONS=`ls "$SNAP_POINT".*`
#echo "My choices are: $SNAP_POINT_OPTIONS"
if ! [ "$SNAP_POINT_OPTIONS" = "$SNAP_DEL" ]
then
for SP in $SNAP_POINT_OPTIONS
do
if ! ls "$SP".* > /dev/null 2>&1
then
if ! [ "$SP" = "$SNAP_DEL" ]
then
SNAP_POINT="$SP"
fi
fi
done
#else
# echo "Oops. guess I don't need to look after all"
fi
elif [ "$SNAP_POINT" = "$SNAP_DEL" ]
then
#echo "Opps. Del point = Snap point. trying to fix..."
local FCOUNT=`echo $SNAP_POINT | grep -o "\." | wc -l`
((FCOUNT++))
LAST_FLD=`echo $SNAP_POINT | cut -d '.' -f $FCOUNT`
SNAP_POINT=`echo $SNAP_POINT | sed "s/\.$LAST_FLD//g"`
fi
echo "*****************************************************************"
echo " Deleting snapshot: $SNAP_DEL"
echo " Reverting to snapshot: $SNAP_POINT"
echo "*****************************************************************"
if [ -L "$DISK" ]
then
rm -f "$DISK"
fi
rm -f "$DISK".*._working
rm -f "$SNAP_DEL"*
"$QEMU_IMG_CMD" create -f qcow2 -b "$SNAP_POINT" "$SNAP_POINT"._working
ln -s "$SNAP_POINT"._working "$DISK"
# remove snapshot description
sed -i "/$SNAP_DEL.*/d" ."$DISK".snap_descriptions
}
###################################################################################
# Main Code Body
###################################################################################
get_options $*
cd "$DISK_PATH"
test_disk "$DISK_IMAGE"
case "$MODE" in
create)
echo "*****************************************************************"
create_snapshot "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
;;
branch)
branch_at_snapshot "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
;;
revert)
revert_to_snapshot "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
;;
remove)
remove_snapshots "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
;;
list)
list_snapshots "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
;;
# Disabled until I can figure out how to merge cow snapshots
# delete)
# delete_snapshot "$DISK_IMAGE" "$SNAPSHOT_NAME" "$SNAPSHOT_DESCR"
# ;;
help)
description
usage
;;
esac
exit 0
