icinga2-checks/check_systemd_service.sh

#!/bin/bash

function usage {
  echo "Usage:
  -u [UNIT name]
  -t Service is triggered by a timer and is allowed to be inactive"
}

# Initialize variables
UNIT=""
IS_TIMER=false

# Parse command line arguments
while getopts "u:t" opt; do
  case ${opt} in
    u )
      UNIT=$OPTARG
      ;;
    t )
      IS_TIMER=true
      ;;
    \? )
      echo "Invalid option: $OPTARG" 1>&2
      exit 1
      ;;
    : )
      echo "Invalid option: $OPTARG requires an argument" 1>&2
      exit 1
      ;;
  esac
done
shift $((OPTIND -1))

# Check if UNIT name is provided
if [ -z "$UNIT" ]; then
    usage
    exit -1
fi

# Check if the unit is enabled
enabled=$(systemctl is-enabled "$UNIT")
if [ "$enabled" != "enabled" ]; then
    echo "CRITICAL - $UNIT is not enabled"
    exit 2
fi

# Check if the unit is active
active=$(systemctl is-active "$UNIT")
substate=$(systemctl show "$UNIT" --property=SubState --value)

if [ "$active" = "activating" ]; then
    echo "WARNING - $UNIT is activating"
    exit 1
elif [ "$active" != "active" ] || { [ "$substate" = "exited" ] && [ "$IS_TIMER" = false ]; }; then
    echo "CRITICAL - $UNIT is not active"
    exit 2
fi

if [ "$IS_TIMER" = true ] && [ "$substate" = "exited" ]; then
    echo "OK - $UNIT is active (exited) and enabled"
else
    echo "OK - $UNIT is active and enabled"
fi
exit 0