add check systemd failed

files/nrpe/check_systemd_failed

@@ -0,0 +1,63 @@
+#!/bin/bash
+#
+# =============================================================================
+#
+# Nagios plugin to check for failed systemd services.
+#
+# Author: GitHub Copilot
+# Version: 1.1
+#
+# =============================================================================
+#
+# This script checks for any systemd services that have entered a "failed"
+# state. It is designed to be used as a Nagios check command.
+#
+# It correctly parses the output from 'systemctl' to identify the service
+# name, even if the output line starts with a special character like '●'.
+#
+# Nagios Exit Codes:
+# 0 - OK: No failed services found.
+# 1 - WARNING: (Not used by this script)
+# 2 - CRITICAL: One or more services are in a failed state.
+# 3 - UNKNOWN: The script could not determine the status of services.
+#
+# =============================================================================
+
+# --- Nagios Exit Codes ---
+STATE_OK=0
+STATE_WARNING=1
+STATE_CRITICAL=2
+STATE_UNKNOWN=3
+
+# --- Script ---
+
+# Use systemctl to find failed services.
+# The --plain option removes special characters and formatting, making output more stable.
+# The output of this command will be lines like:
+# prometheus-nginx-exporter.service loaded failed failed Prometheus Nginx Exporter
+failed_services_output=$(systemctl list-units --type=service --state=failed --no-legend --plain)
+
+# Check if the systemctl command executed successfully.
+if [ $? -ne 0 ]; then
+    echo "UNKNOWN: Could not query systemd for failed services. Is systemctl available?"
+    exit $STATE_UNKNOWN
+fi
+
+# Check if the output is empty, which means no failed services.
+if [ -z "$failed_services_output" ]; then
+    echo "OK: All systemd services are running correctly."
+    exit $STATE_OK
+else
+    # Use awk to extract the first column (the service name) from each line.
+    failed_service_names=$(echo "$failed_services_output" | awk '{print $1}')
+
+    # Count the number of failed services.
+    service_count=$(echo "$failed_service_names" | wc -l)
+
+    # Join the service names with a comma and space for a clean list.
+    service_list_formatted=$(echo "$failed_service_names" | tr '\n' ',' | sed 's/,/, /g' | sed 's/, $//')
+
+    # Output the critical message for Nagios.
+    echo "CRITICAL: Found $service_count failed systemd service(s): $service_list_formatted"
+    exit $STATE_CRITICAL
+fi