monitoring/check_dhcp.sh

#!/usr/bin/env bash

# - Which Service should be checkked
# -
# - This parameter MUST be given
# -
_service_name="DHCP"

# - The binary of the service
# -
# - If not given, script dries to determin it.
# -
_check_binary="$(which dhcpd)"

# - The systemd service file
# -
# - If not given, script dries to determin it.
#
#_SYSTEMD_SERVICE="isc-dhcp-server"

# - The sysv init script of the service
# -
# - If not given, script dries to determin it.
#
_SYSV_INIT_SCRIPT="isc-dhcp-server"


#---------------------------------------
#-----------------------------
# Base Function(s)
#-----------------------------
#---------------------------------------

fatal(){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[31m\033[1mFatal\033[m ] $*"
   else
      echo -e "   [ Fatal ] $*"
   fi
   echo ""
   if $terminal ; then
      echo -e "             \033[1mScript terminated\033[m.."
   else
      echo -e "             Script terminated.."
   fi
   echo ""
   rm -rf $LOCK_DIR
   exit 1
}

error (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[31m\033[1mError\033[m ] $*"
   else
      echo "   [ Error ] $*"
   fi
   echo ""
}

warn (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[33m\033[1mWarn\033[m ]  $*"
   else
      echo "   [ Warn ]  $*"
   fi
   echo ""
}

info (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[32m\033[1mInfo\033[m ]  $*"
   else
      echo "   [ Info ]  $*"
   fi
   echo ""
}

ok (){
   echo ""
   if $terminal ; then
      echo -e "   [ \033[32m\033[1mOk\033[m ]    $*"
   else
      echo "   [ Ok ]    $*"
   fi
   echo ""
}

trim() {
    local var="$*"
    var="${var#"${var%%[![:space:]]*}"}"   # remove leading whitespace characters
    var="${var%"${var##*[![:space:]]}"}"   # remove trailing whitespace characters
    echo -n "$var"
}


#---------------------------------------
#-----------------------------
# Check some prerequisites
#-----------------------------
#---------------------------------------

LOCK_DIR=`mktemp -d`

# - Running in a terminal?
# -
if [[ -t 1 ]] ; then
   terminal=true
   LOGGING=true
else
   terminal=false
   LOGGING=false
fi

if [[ -n "$_service_name" ]]; then
   service_name=$_service_name
else
   fatal "$(basename $0): No Service given"
fi

# - Is Service installed ?
# -
if [[ -z "$_check_binary" ]]; then
   _check_binary="$(which ${service_name,,}d)"
   if [[ -z "$_check_binary" ]] ; then
      _check_binary="$(which ${service_name,,})"
   fi
fi


if [[ -z "$_check_binary" ]]; then
   fatal "$(basename $0): $service_name Service seems NOT to be installed"
else
   check_binary="$_check_binary"
   check_string_ps="$check_binary"
fi


# - Systemd supported ?
# -
systemd=$(which systemd)
systemctl=$(which systemctl)

systemd_supported=false
if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
   systemd_supported=true
fi

SYSTEMD_SERVICE=
SYSV_INIT_SCRIPT=

if $systemd_supported ; then
   if [[ -n "$_SYSTEMD_SERVICE" ]] ; then
         if systemctl -t service list-unit-files \
               | grep -e "^$_SYSTEMD_SERVICE" \
               | grep -q -E "(enabled|disabled)" 2> /devnull ; then

            SYSTEMD_SERVICE="$(systemctl -t service list-unit-files | grep -e "^$_SYSTEMD_SERVICE" | awk '{print$1}' | head -1)"
         fi
   else
      if systemctl -t service list-unit-files \
            | grep -e "^${service_name,,}d" \
            | grep -q -E "(enabled|disabled)" 2> /devnull ; then

         SYSTEMD_SERVICE="$(systemctl -t service list-unit-files | grep -e "^${service_name,,}d" | awk '{print$1}' | head -1)"
      elif systemctl -t service list-unit-files \
            | grep -e "^${service_name,,}" \
            | grep -q -E "(enabled|disabled)" 2> /devnull ; then

         SYSTEMD_SERVICE="$(systemctl -t service list-unit-files | grep -e "^${service_name,,}" | awk '{print$1}' | head -1)"
      fi
   fi
fi

if [[ -z "$SYSTEMD_SERVICE" ]]; then
   if [[ -n "$_SYSV_INIT_SCRIPT" ]]; then
      if [[ -x "/etc/init.d/$_SYSV_INIT_SCRIPT" ]]; then
         SYSV_INIT_SCRIPT="/etc/init.d/$_SYSV_INIT_SCRIPT"
      fi
   fi
   if [[ -z "$SYSV_INIT_SCRIPT" ]] ; then
      if [[ -x "/etc/init.d/${service_name,,}" ]]; then
         SYSV_INIT_SCRIPT="/etc/init.d/${service_name,,}"
      elif [[ -x "/etc/init.d/${service_name,,}d" ]]; then
         SYSV_INIT_SCRIPT="/etc/init.d/${service_name,,}d"
      fi
   fi
fi

if [[ -z "$SYSTEMD_SERVICE" ]] && [[ -z "$SYSV_INIT_SCRIPT" ]] ; then
   fatal "Neither an init-script nor a service file for $service_name found!"
fi


#---------------------------------------
#-----------------------------
# Check if SSH service is running
#-----------------------------
#---------------------------------------

if $LOGGING ; then
   echo -e "\n   Check if $service_name service is running.."
   echo -e "   ================================="
fi
if ! ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}" | grep -v grep > /dev/null ; then
   error "$service_name service seems to be down! Trying to restart service now.."

   if [[ -n "$SYSTEMD_SERVICE" ]] ; then
      $systemctl daemon-reload > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
      sleep 2
      $systemctl stop $SYSTEMD_SERVICE > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
      sleep 10
      $systemctl start $SYSTEMD_SERVICE > /dev/null 2> ${LOCK_DIR}/err_msg.log
      if [[ $? -ne 0 ]]; then
         error "$(cat ${LOCK_DIR}/err_msg.log)"
      fi
   else
      $SYSV_INIT_SCRIPT stop > /dev/null 2>&1
      if [[ $? -ne 0 ]]; then
         error "Stopping $service_name service failed!"
      fi
      sleep 10
      $SYSV_INIT_SCRIPT start > /dev/null 2>&1
      if [[ $? -ne 0 ]]; then
         error "Starting $service_name service failed!"
      fi
   fi

   declare -i counter=0
   PID=$(ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}"| grep -v grep | awk '{print$2}')
   while [[ "X${PID}" = "X" ]]; do
      sleep 1
      PID=$(ps -e f | grep -E "[[:digit:]]\ ${check_string_ps}"| grep -v grep | awk '{print$2}')
      if [[ $counter -gt 10 ]]; then
         break
      else 
         ((counter++))
      fi
   done

   if [[ "X${PID}" = "X" ]] ; then
      error "Restarting $service_name service failed!"
   else
      ok "$service_name service is up and running."
   fi
         
else
   if $LOGGING ; then
      ok "$service_name service is up and running."
   fi
fi

rm -rf $LOCK_DIR
exit 0