#!/bin/bash
#
# Author: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
# Date: 2009-10-08
# License: GPL v3+

#set -x

CMD="$1"
shift

NAME="$1"
# FIXME: make this default to the only vg (if only one vg exists), or to vg_$(hostname0) or $(hostname), if those VGs exist
VG="${2:-vg_$(hostname)0}"
SIZE="${3:-3G}"
RAM="${4:-512}"
DISK="/dev/mapper/${VG}-${NAME}"

if [ -z "$CREATE_USER" ]; then    
    CREATE_USER="yes"
fi

# for managing udev (we want to make sure that logical volumes get
# created with ownership by the controlling user:
UDEV_RULES_FILE="/etc/udev/rules.d/92-kvm_creator-%s.rules"
# Why choose 92?  /usr/share/doc/udev/README.Debian.gz says after 91
# default permissions and ownership are set.

[ "$CMD" == "create" ] && mkdir -p /etc/sv/kvm

usage() {
	die "USAGE: kvm-creator create|destroy|demo guestname [volumegroup [disksize [ram] ] ]"
}

die() {
  echo "$1"
  exit_code=1
  [ -n "$2" ] && exit_code="$2"
  exit $exit_code
}

destroy() {
    update-service --remove "/etc/sv/kvm/$NAME"
    rm -rf "/etc/sv/kvm/$NAME"
    deluser --remove-home "$NAME"
    lvremove "$VG/$NAME"
    rm -f "$(udevrulename "$NAME")"
}

validate() {
  errors=""

  # Make sure none of the pieces already exist.
  [ -z "$NAME" ] && errors=$(printf "%s\n%s" "$errors" "Please pass the name of the virtual server to create") || :
  [ -z "$VG" ] && errors=$(printf "%s\n%s" "$errors"  "Please pass the name of the volume group to use") || :
  vgs --noheadings --unbuffered -o name | tr -d ' ' | grep -q -F -x "$VG" || errors=$(printf "%s\n%s" "$errors"  "Please pass the name of the volume group to use") || :
  if [ "$CREATE_USER" = "yes" ]; then
      getent passwd "$NAME" > /dev/null && errors=$(printf "%s\n%s" "$errors" "The username '$NAME' already exists.") || :
      getent group "$NAME" > /dev/null && errors=$(printf "%s\n%s" "The group '$NAME' already exists.") || :
      [ -d /home/"$NAME" ] && errors=$(printf "%s\n%s" "The directory '/home/$NAME' already exists.") || :
  fi
  [ -d /etc/sv/kvm/"$NAME" ] && errors=$(printf "%s\n%s" "The directory '/etc/sv/kvm/$NAME' already exists.") || :
  [ -e $DISK ] && errors=$(printf "%s\n%s" "The logical volume $NAME already exists.") || :
  [ -e "$(udevrulename "$NAME")" ] && errors=$(printf "%s\n%s" "The udev rules file '$(udevrulename "$NAME")' already exists.") || :

  [ -z "$errors" ] || die "$errors"
}

udevrule() {
    VOLUME_GROUP="$1"
    LOGICAL_VOLUME="$2"
    GROUP="$3"

    # this appears to be the way that a udev rule to control the LVM device gets created:
    printf 'ACTION=="change", SUBSYSTEM=="block", ATTR{dm/name}=="%s-%s", GROUP="%s"\n' "$VOLUME_GROUP" "$LOGICAL_VOLUME" "$GROUP" 

    # unfortunately, kernel 2.6.26-2-amd64 (from debian) does not
    # appear to export /sys/block/dm-%d/dm/name ; nether does
    # 2.6.28-16-generic (ubuntu);  2.6.30-2-686 *does* export that
    # label, so the above line works on squeeze at the moment.

    # not sure what to do about this for lenny systems.  See:
    # http://bugs.debian.org/450793
}

udevrulename() {
    printf "$UDEV_RULES_FILE" "$1"
}

create() {
    set -e
    validate
    if [ "$CREATE_USER" = "yes" ]; then
        adduser "$NAME" --disabled-password --gecos "$NAME KVM user,,,"
    fi
    USERHOMEDIR=$(getent passwd "$NAME" | cut -f6 -d:)
    chpst -u "$NAME:$NAME" mkdir -p "$USERHOMEDIR/"{.ssh,vms,"vms/$NAME"}
    if [ -f /root/.ssh/authorized_keys ]; then
        # is this really the right thing to do?
        cp /root/.ssh/authorized_keys "$USERHOMEDIR/.ssh/"
    fi
    USERGID="$(getent passwd "$NAME")"
    USERGID="$(cut -f4 -d: <<<$USERGID)"
    USERGROUP="$(getent group "$USERGID")"
    USERGROUP="${USERGROUP%%:*}"
 
    udevrule "$VG" "$NAME" "$USERGROUP" > $(udevrulename "$NAME")

    lvcreate --name "$NAME" --size "$SIZE" $VG
    mkdir "/etc/sv/kvm/$NAME"{,/log,/env}
    cat > "/etc/sv/kvm/$NAME/log/run" <<EOF
#!/bin/sh

exec 2>&1
exec chpst -e ../env /usr/local/sbin/kvm-manager log
EOF
    cat > "/etc/sv/kvm/$NAME/run" <<EOF
#!/bin/sh

exec 2>&1
exec chpst -e ./env /usr/local/sbin/kvm-manager up
EOF
    cat > "/etc/sv/kvm/$NAME/finish" <<EOF
#!/bin/sh

exec 2>&1
exec chpst -e ./env /usr/local/sbin/kvm-manager down
EOF
    chmod a+x "/etc/sv/kvm/$NAME/"{run,finish,log/run}
    echo "$NAME" > "/etc/sv/kvm/$NAME/env/OWNER"
    echo "$NAME" > "/etc/sv/kvm/$NAME/env/VMNAME"
    echo "$RAM" > "/etc/sv/kvm/$NAME/env/RAM"
    echo "$DISK" > "/etc/sv/kvm/$NAME/env/HDA"
}

demo() {
    validate
    for foo in NAME VG SIZE RAM DISK ; do
      echo "$foo : ${!foo}"
    done
}

[ "$CMD" != "create" ] && [ "$CMD" != "destroy" ] && [ "$CMD" != "demo" ] && usage

"$CMD"