snap-guest

#!/bin/bash

usage() {
cat <<USAGE
usage: $0 options

Tool for ultra-fast copy-on-write image provisioning. Prepare a base image (or
download a cloud image) and then spawn an COW instance. Then again, and again.

OPTIONS:
  --help | -h
        Show this message
  --list | -l
        List avaiable images (with "base" in the name)
  --list-all
        List all images
  --base [image] | -b [image]
        Base image name (template) - required
  --target [name] | -t [name]
        Target image name (and hostname) - required
  --network [opts] | -n [opts]
        Network options for virt-install (default: "network=default")
  --network2 [opts]
        Second network NIC settings (none by default)
  --memory [MB] | -m [MB]
        Memory (default: 800 MiB)
  --cpus [CPUs] | -c [CPUs]
        Number of CPUs (default: 1)
  --image-dir [path] | -p [path]
        Target images path (default: /var/lib/libvirt/images/)
  --base-image-dir [path]
        Base images path (default: /var/lib/libvirt/images/)
  --domain [domain] | -d [domain]
        Domain suffix like "mycompany.com" (default: none)
  --domain-prefix [prefix]
        Domain prefix like "test-" -> "test-NAME.lan" (default: none)
  --force | -f
        Force creating new guest (destroy existing, no questions, DANGEROUS!)
  --add-ip | -w
        Add IP address to /etc/hosts on the host machine (works only with NAT)
  --graphics [opts] | -g [opts]
        Graphics options passed to virt-install via --graphics
        (default is vnc,listen=0.0.0.0)
  --swap [MBs] | -s [MBs]
        Creates RAW disk and connects and mounts it as swap of given size.
        The created virtual disc is NOT parititioned (it is used raw).
        For cloud-image provisioning swap is created but ignored and
        you need to do this manually in user-data script (swapon /dev/vdb).
  --firstboot [command] | -1 [command]
        Command to execute during first boot in /root dir
        (logfile available in /root/firstboot.log)
  --cloud-image
        Disables image manipulation and enables cloud-init seed via CD-ROM
  --cloud-preconf
        Run image manipulation (MAC address, hostname setting, fstab) even
        when operating in the cloud mode
  --user-data-file [file]
        Reads cloud-init user-data from file
  --user-data-ssh
        Generate primitive user-data file with only your public ssh key
  --user-data-stdin
        Reads cloud-init user-data from standard input
        (overrides all --user-data-* options)
  --boot-script [filename] | -i [filename]
        Appends a bash bootstrip to the user-data. Can be used multiple times.
  --boot-script-prefix [directory]
        Prepend directory to each boot script (so -i options can be shorter).
  --static-ipaddr
        It is possible to configure static network setup (only Fedora/RHEL).
  --static-netmask
        It is possible to configure static network setup (only Fedora/RHEL).
  --static-gateway
        It is possible to configure static network setup (only Fedora/RHEL).
  --cpu-feature
        Configure the CPU model and CPU features exposed to the guest.

EXAMPLE:

  $0 --list
  $0 -p /mnt/data/images --list-all
  $0 -b fedora-17-base -t test-vm -s 4098
  $0 -b fedora-17-base -t test-vm2 -n bridge=br0 -d example.com
  $0 -b rhel-6-base -t test-vm -m 2048 -c 4 -p /mnt/data/images
  echo "my user data" | $0 -b f19 -t aa --cloud-image --user-data-stdin \\
    -n bridge=br0 -d xxx.redhat.com --domain-prefix 'lzap-' -s 2048 -f
USAGE
}

# determine script directory
SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do
  DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
  SOURCE="$(readlink "$SOURCE")"
  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE"
done
SCRIPTDIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"

SOURCE_NAME=""
TARGET_NAME=""
NETWORK="network=default"
NETWORK2=""
MEM="800"
SWAP=0
CPUS="1"
IMAGE_DIR="/var/lib/libvirt/images"
BASE_IMAGE_DIR="/var/lib/libvirt/images"
DOMAIN=""
PREFIX=""
FORCE=0
LIST=0
LIST_ALL=0
ADD_IP=0
GRAPHICS_OPTS="vnc,listen=0.0.0.0"
COMMAND=""
CLOUD=0
CLOUD_PRECONF=0
USER_DATA_STDIN=0
USER_DATA_FILE=""
USER_DATA_SSH=0
BOOT_SCRIPTS=()
BOOT_SCRIPT_PREFIX=""
STATIC_IPADDR=""
STATIC_NETMASK=""
STATIC_GATEWAY=""
CPU_FEATURE=""

if ! options=$(getopt -o hlfwb:t:n:m:c:d:p:s:1:g:i: -l list,list-all,force,add-ip,image-dir:,base-image-dir:,base:,graphics:,target:,network:,network2:,memory:,cpus:,domain:,domain-prefix:,swap:,firstboot:,cloud-image,cloud-preconf,user-data-ssh,user-data-stdin,user-data-file:,boot-script,boot-script-prefix:,static-ipaddr:,static-netmask:,static-gateway:,cpu-feature:,help -- "$@"); then
  exit 1
fi

eval set -- $options

while [ $# -gt 0 ]; do
    case $1 in
    --list|-l) LIST=1 ;;
    --list-all) LIST_ALL=1 ;;
    --force|-f) FORCE=1 ;;
    --add-ip|-w) ADD_IP=1 ;;
    --image-dir|-p) IMAGE_DIR="$2" ; shift ;;
    --base-image-dir) BASE_IMAGE_DIR="$2" ; shift ;;
    --base|-b) SOURCE_NAME="$2" ; shift ;;
    --graphics|-g) GRAPHICS_OPTS="$2" ; shift ;;
    --target|-t) TARGET_NAME="$2" ; shift ;;
    --network|-n) NETWORK="$2" ; shift ;;
    --network2) NETWORK2="--network=$2" ; shift ;;
    --memory|-m) MEM="$2" ; shift ;;
    --cpus|-c) CPUS="$2" ; shift ;;
    --domain|-d) DOMAIN=".$2" ; shift ;;
    --domain-prefix) PREFIX="$2" ; shift ;;
    --swap|-s) SWAP="$2" ; shift ;;
    --firstboot|-1) COMMAND="$2" ; shift ;;
    --cloud-image) CLOUD=1 ;;
    --cloud-preconf) CLOUD_PRECONF=1 ;;
    --user-data-stdin) USER_DATA_STDIN=1 ;;
    --user-data-ssh) USER_DATA_SSH=1 ;;
    --user-data-file) USER_DATA_FILE="$2" ; shift ;;
    --boot-script|-i) BOOT_SCRIPTS+=("$BOOT_SCRIPT_PREFIX$2:text/x-shellscript") ; shift ;;
    --boot-script-prefix) BOOT_SCRIPT_PREFIX="$2/" ; shift ;;
    --static-ipaddr) STATIC_IPADDR="$2" ; shift ;;
    --static-netmask) STATIC_NETMASK="$2" ; shift ;;
    --static-gateway) STATIC_GATEWAY="$2" ; shift ;;
    --cpu-feature) CPU_FEATURE="--cpu=$2" ; shift ;;
    --help|-h) usage;  exit ;;
    (--) shift; break;;
    (-*) echo "$0: error - unrecognized option $1" 1>&2; exit 1;;
    (*) break;;
    esac
    shift
done

[ $LIST -eq 1 ] && ls "$BASE_IMAGE_DIR" | grep '\.img' | grep base | sed 's/\.img//g' && exit 0
[ $LIST_ALL -eq 1 ] && ls "$BASE_IMAGE_DIR" | grep '\.img' | sed 's/\.img//g' && exit 0

if [ -z "$SOURCE_NAME" -o -z "$TARGET_NAME" ]; then
  usage; exit 1
fi

# Check prerequisites
for BINARY in getopt virsh qemu-img mkswap sed tail openssl hexdump perl genisoimage virt-install; do
  if ! type -p $BINARY >/dev/null ; then
    echo "Please install '$BINARY' first to use snap-guest!" 1>&2
    echo "See https://github.com/lzap/snap-guest#installation" 1>&2
    exit 1
  fi
done

SOURCE_IMG=$(ls -v1 $BASE_IMAGE_DIR/${SOURCE_NAME}*.img | tail -n1)
TARGET_IMG=$IMAGE_DIR/$TARGET_NAME.img
TARGET_IMG_SWAP=$IMAGE_DIR/$TARGET_NAME-swap.img
MAC="52:54:00$(echo "$(hostname)$TARGET_NAME" | openssl dgst -md5 -binary | hexdump -e '/1 ":%02x"' -n 3)"
TARGET_HOSTNAME="$PREFIX$TARGET_NAME$DOMAIN"

if [ ! -f "$SOURCE_IMG" ]; then
  echo "Base image $SOURCE_IMG not found!"
  exit 1
fi

if [ -f "$TARGET_IMG" ]; then
  echo "Target image already exists!"
  if [ $FORCE -eq 1 ]; then
    REPLY="y"
  else
    read -p "Shutdown and remove host with this name first (y/[n])? "
  fi
  [ "$REPLY" != "y" ] && \
    # need to do it twice (sometimes this fail)
    virsh destroy "$TARGET_NAME" 2>/dev/null; sleep 2s; \
    virsh destroy "$TARGET_NAME" 2>/dev/null; sleep 1s; \
    virsh undefine "$TARGET_NAME"
fi

echo "Creating snapshot guest $TARGET_NAME"

# -- Image Creation --------------

echo "Creating snapshot image"
qemu-img create -f qcow2 -b $SOURCE_IMG $TARGET_IMG

# -- Image Manipulation ----------

if [ $CLOUD -eq 0 -o $CLOUD_PRECONF -eq 1 ]; then
  export COMMAND TARGET_HOSTNAME MAC SOURCE_NAME SWAP TARGET_IMG TARGET_NAME \
    STATIC_IPADDR STATIC_NETMASK STATIC_GATEWAY
  perl -w "$SCRIPTDIR/prepare-image.pl"
fi

# -- Cloud Init -----------------

if [ $CLOUD -eq 1 ]; then
  echo "Generating cloud-init seed"
  TARGET_IMG_SEED="$IMAGE_DIR/seed-$TARGET_NAME.iso"
  CITEMP=$(mktemp -d)
  trap "rm -rf $CITEMP" EXIT
  # prepare metadata
  cat > "$CITEMP/meta-data" <<EOS
instance-id: $TARGET_HOSTNAME
local-hostname: $TARGET_HOSTNAME
EOS
  # prepare userdata
  [ ! -z "$USER_DATA_FILE" ] && cp "$USER_DATA_FILE" "$CITEMP/user-data"
  [ $USER_DATA_SSH -eq 1 ] && cat > "$CITEMP/user-data" <<EOS
#cloud-config
disable_root: 0
ssh_authorized_keys:
 - $(cat ~/.ssh/id_rsa.pub)
EOS
  [ $USER_DATA_STDIN -eq 1 ] && cat > "$CITEMP/user-data" </dev/stdin
  if [ ! -f "$CITEMP/user-data" ]; then
    echo "Please provide at least one --user-data option" 1>&2; exit 1
  fi
  # concatenate user-data
  if [ ${#BOOT_SCRIPTS[@]} -gt 0 ]; then
    mv "$CITEMP/user-data" "$CITEMP/user-data-main"
    write-mime-multipart ${BOOT_SCRIPTS[@]} "$CITEMP/user-data-main" > "$CITEMP/user-data"
  fi

  pushd "$CITEMP" 2>/dev/null
  genisoimage -output $TARGET_IMG_SEED -volid cidata -joliet -rock user-data meta-data
  popd 2>/dev/null
  cat "$CITEMP/user-data"
  DISK_SEED="--disk $TARGET_IMG_SEED,device=cdrom"
else
  DISK_SEED=""
fi

# -- Swap Creation --------------

if [ $SWAP -gt 0 ]; then
  qemu-img create -f raw $TARGET_IMG_SWAP ${SWAP}M
  mkswap -f $TARGET_IMG_SWAP
  DISK_SWAP="--disk $TARGET_IMG_SWAP,device=disk,bus=virtio,format=raw"
else
  DISK_SWAP=""
fi

# -- Image Provisioning ---------

echo "Provisioning guest $TARGET_NAME"
echo "Hostname: $TARGET_HOSTNAME"
echo "CPUs:     $CPUS"
echo "Memory:   $MEM MB"
echo "Swap:     $MEM MB"
echo "MAC:      $MAC"
virt-install --vcpus $CPUS \
  --ram $MEM --import \
  --name $TARGET_NAME \
  --disk $TARGET_IMG,device=disk,bus=virtio,format=qcow2 $DISK_SWAP $DISK_SEED \
  --graphics "$GRAPHICS_OPTS" \
  --noautoconsole --force \
  --network=$NETWORK,mac=$MAC \
  $NETWORK2 \
  $CPU_FEATURE

# -- IP Determining -------------
# TODO: Use this instead: http://rwmj.wordpress.com/2010/10/26/tip-find-the-ip-address-of-a-virtual-machine/

if [ $ADD_IP -eq 1 ]; then
  echo "Waiting for IP"
  i=0
  until [ $i -ge 100 ] || IP_LINE=`cat /var/lib/libvirt/dnsmasq/${NETWORK/network=}.leases /var/lib/dnsmasq/dnsmasq.leases 2>/dev/null | grep "$MAC"`; do
    i=$((i + 1))
    sleep 1
  done

  if [[ -n $IP_LINE ]]; then
    IP=`echo  $IP_LINE | awk '{print $3}'`
    if ! grep -q "$TARGET_HOSTNAME\$" /etc/hosts; then
      echo "Writing into /etc/hosts ip: $IP"
      echo "$IP $TARGET_HOSTNAME $TARGET_NAME" >> /etc/hosts
    else
      echo "Host $TARGET_HOSTNAME already in hosts"
      OLD_IP=`grep "$TARGET_HOSTNAME\$" /etc/hosts | head -n 1 | awk '{print $1}'`
      if [[ $IP = $OLD_IP ]]; then
        echo "and these ip's match"
      else
        echo "with different ip: $OLD_IP instead of $IP"
      fi
    fi
  fi
fi

# -- EOF --