#!/bin/bash
#

sanity_check() {
  # check if there are more than one LV
  lvs=$(lvs | grep -c "_img.*Xen")
  if [ "${lvs}" -gt 1 ]; then
    echo "guest_status - found more than 1 LV image - please remove the unused one"
    exit 1
  fi

  # check if there's LV existing
  if [[ -n ${guest_lv} ]]; then
    # check if domU is not running
    if [ -z "${xl_list}" ]; then
      xen_vm_running=0
    # othewise let's compare the two variables below to see if their values match, which means there's a guest VM provisioned and it's running
    elif [[ ${xl_list} == "${guest_lv}" ]]; then
      xen_vm_running=1
    fi

    xl_cfg=/home/xen/${guest_lv}/${guest_lv}.cfg
    guest_vm_ip=$(grep ^vif "${xl_cfg}" | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}' | head -1)
    guest_vm_hostname=$(grep hostname "${xl_cfg}" | sed "s/hostname   = '//g; s/'//g" | tr -d '\n' )
  else
    echo "guest_status - No VM is provisioned"
    exit 1
  fi
}

check_guest() {
  guest_lv=$(lvs | grep img | awk '{print $1}' | sed 's/_img//g')
  xl_list=$(xl list | grep vm | awk '{print $1}')

  sanity_check
}

check_status() {
  status=0

  # different status checks, each with 2 seconds timeout to speed it up and prevent unexpected issues in #nag
  if ping -c 1 -w 2 "${guest_vm_ip}" &> /dev/null; then
    # guest VM is responding to Ping check
    status=1
  elif nc -zv -w 2 "${guest_vm_ip}" 80 &> /dev/null; then
    # guest VM is responding to HTTP check
    status=1
  elif nc -zv -w 2 "${guest_vm_ip}" 7822 &> /dev/null; then
    # guest VM is responding to SSH check
    status=1
  fi
}

main() {
  # first check if a2_status file is present - this will prevent flooding #nag for CRIT alerts
  if [ -f "/root/a2_status" ]; then
    # check if the guest VM is now responding to any of the checks, then delete the a2_status file
    check_status
    if [ ${status} == 1 ]; then
      echo "guest_status - ${guest_vm_ip} [${guest_vm_hostname}] is running and responding to status checks"
      exit 0

      # delete the a2_status file
      rm -f /root/a2_status
    elif [ ${status} == 0 ]; then
      echo "guest_status - ${guest_vm_ip} [${guest_vm_hostname}] is offline and ACK'd - $(cat /root/a2_status)"
      exit 1
    fi
  # if there's no a2_status file is present, then check if the guest VM is not running
  elif [[ ${xen_vm_running} == 0 ]]; then
    # at this stage, monitoring guys will just need to power ON the guest VM (only if it's Active in WHMCS)
    echo "guest_status - ${guest_vm_ip} [${guest_vm_hostname}] is offline - please check the server"
    exit 2
  # otherwise if the guest VM is running - run check_status function
  elif [[ ${xen_vm_running} == 1 ]]; then
    check_status
    if [ ${status} == 1 ]; then
      echo "guest_status - ${guest_vm_ip} [${guest_vm_hostname}] is running and responding to status checks"
      exit 0
    elif [ ${status} == 0 ]; then
      # this is the time when monitoring guys will touch a2_status file in /root dir and put the bug-ID, then investigate the issue
      echo "2 guest_status - ${guest_vm_ip} [${guest_vm_hostname}] is not responding to status checks - please check the server"
      exit 2
    fi
  fi
}

check_guest
main