# !/bin/bash -e
# nrpe client installer for CentOS and Ubuntu
# Info: This script installs a NRPE client, following [1]
# [1] https://support.nagios.com/kb/article.php?id=515
# For use on clean CentOS or Ubuntu box only
# Usage:
# wget https://raw.githubusercontent.com/DavidGhedini/nagios-webmin-module/master/scripts/pre-install.sh
# chmod +x pre-installer
# ./pre-installer.sh



#Nagious server, that will monitor this client node
NAGIOS_MON_HOST='1.2.3.4'
NAGIOS_HOME='/usr/local/nagios/'

function detect_distro(){
  if [ -f /etc/centos-release ]; then
		DISTRO='centos'
		DISTRO_VER=$(grep VERSION_ID /etc/os-release | tr -d '"' | cut -f2 -d= | cut -f1 -d.)

  #opensuse,debian,slackware, ubuntu
	elif [ -f /etc/os-release ]; then
		DISTRO=$(grep -m 1 ID /etc/os-release | cut -f2 -d= | tr -d '"')
		DISTRO_VER=$(grep VERSION_ID /etc/os-release | tr -d '"' | cut -f2 -d= | cut -f1 -d.)
	else
		echo "Error: Failed to detect distribution"; exit 1;
	fi
}

function install_deps(){

  if [ ${DISTRO} == 'centos' ]; then
    yum install -y gcc glibc glibc-common openssl openssl-devel perl wget
  elif [ ${DISTRO} == 'ubuntu' ]; then
    export DEBIAN_FRONTEND=noninteractive
    if [ ${DISTRO_VER} -eq 18 ]; then
      apt-add-repository universe
    fi
    apt-get install -y autoconf automake gcc libc6 libmcrypt-dev make libssl-dev wget openssl make
  fi
}

function install_nrpe(){
  NRPE_VER='3.2.1'

  if [ $(grep -m 1 -c '^nagios:' /etc/passwd) -eq 0 ]; then
    useradd -s /bin/false nagios
  fi

  pushd ${HOME}
    if [ ! -f nrpe-${NRPE_VER}.tar.gz ]; then
      wget --no-check-certificate https://github.com/NagiosEnterprises/nrpe/archive/nrpe-${NRPE_VER}.tar.gz
    fi

    tar xzf nrpe-${NRPE_VER}.tar.gz
    rm -f nrpe-${NRPE_VER}.tar.gz

    pushd nrpe-nrpe-${NRPE_VER}/

      if [ $(which systemctl 2>/dev/null | grep -c yum) -eq 1 ]; then
        ./configure --enable-command-args --with-init-type=systemd
      else
        ./configure --enable-command-args
      fi

      make all install install-groups-users install-plugin install-config install-init
    popd
    rm -f nrpe-nrpe-${NRPE_VER}/
  popd
}

function config_nrpe(){

  sed -i "/^allowed_hosts=/s/\$/,${NAGIOS_MON_HOST}/" ${NAGIOS_HOME}/etc/nrpe.cfg
  sed -i 's/^dont_blame_nrpe=.*/dont_blame_nrpe=1/g'  ${NAGIOS_HOME}/etc/nrpe.cfg

  #Standard command found in source/package plugins
  cat >> ${NAGIOS_HOME}/etc/nrpe.cfg <<CMD_EOF
  command[check_disk_root]=${CUSTOM_PLUGINS_HOME}/check_disk -w 30% -c 10% -p /
CMD_EOF

  cat >> ${NAGIOS_HOME}/etc/nrpe.cfg <<CMD_EOF
command[check_linuxdiskspace]=${CUSTOM_PLUGINS_HOME}/check_linuxdiskspace
CMD_EOF

  #Linux S.M.A.R.T Checks
  #NOTE: we may have /dev/vda1 for virtual disk
  for sd in $(find /dev -type b -name 'sd[a-z][0-9]' | cut -f3 -d/); do
    echo "command[check_linux_smart_${sd}]=${CUSTOM_PLUGINS_HOME}/check_ide_smart -d /dev/${sd}" >> ${NAGIOS_HOME}/etc/nrpe.cfg
  done


  if [ $(which systemctl 2>/dev/null | grep -c systemctl) -eq 1 ]; then
    systemctl enable nrpe.service
    systemctl start nrpe
  else
    chkconfig --set nrpe on
    service nrpe start
  fi
}

function install_plugins_source(){
  PLUG_VER='2.3.1'

  if [ ${DISTRO} == 'centos' ]; then
    yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils epel-release perl-Net-SNMP
  elif [ ${DISTRO} == 'ubuntu' ]; then
    apt-get install -y autoconf gcc libc6 libmcrypt-dev make libssl-dev wget bc gawk dc build-essential snmp libnet-snmp-perl gettext
  fi

  pushd ${HOME}
    wget --no-check-certificate https://github.com/nagios-plugins/nagios-plugins/archive/release-${PLUG_VER}.tar.gz
    tar xzf release-${PLUG_VER}.tar.gz
    rm -f release-${PLUG_VER}.tar.gz

    pushd nagios-plugins-release-${PLUG_VER}/
      ./tools/setup
      ./configure
      make
      make install
    popd
    rm -rf nagios-plugins-release-${PLUG_VER}/
  popd

  NAGIOS_PLUGINS_HOME='/usr/local/nagios/libexec/'
}

#Install plugins not found in source or packages
function install_plugins(){

  install_plugins_source
}

function test_nrpe(){

  if [ ! -f ${NAGIOS_HOME}/etc/nrpe.cfg ]; then
    echo 'Error: nrpe.cfg is missing!'
  fi

  OUT=$(${NAGIOS_HOME}/libexec/check_nrpe -H 127.0.0.1)
  if [ "${OUT}" == "NRPE v${NRPE_VER}" ]; then
    echo "NRPE Test OK"
  else
    echo "NRPE Test FAILED"
    exit 1;
  fi
}

detect_distro;
install_deps;
install_nrpe;
install_plugins;
config_nrpe;

test_nrpe;