Let’s break down what this script does in detail. The script is named cronjob_template.sh, authored by GJS (homelab-alpha), and its purpose is to provide a template for a cron job that sends a ping to a monitoring server for system health checks.

Here’s a detailed explanation:

Script Metadata

  • Filename: cronjob_template.sh
  • Author: GJS (homelab-alpha)
  • Date: May 18, 2024
  • Version: 1.0.1
  • Description: This script serves as a cron job template that sends a ping to a monitoring server to check system health.
  • Usage: The script should be executed with root privileges using sudo.
  • RAW Script: cronjob_template.sh

Script Header

The header includes metadata such as the filename, author, date, version, and a brief description of its functionality.


Usage Instructions

The script provides usage instructions, emphasizing the need for curl to be installed and the script to be run with root privileges. It also includes an example of how to set up a cron job to execute the script at specified intervals.


Cron Job Example

The script includes a template for setting up a cron job. This example runs the script every 3 hours from 07:00 to 23:00:

10 07-23/3 * * * /bin/bash /path/to/.bash_script/cronjob_template.sh

Logging Functions

Several functions handle logging messages to a file:

  • log_message(): Logs a generic message with a timestamp.
  • log_verbose(): Logs verbose messages if the verbose flag is set.
  • log_debug(): Logs debug messages if the debug flag is set.
  • log_warning(): Logs warning messages.

Ping Function

The function send_ping_to_monitor_server() handles sending a ping to the monitoring server:

  • It first attempts to send a ping without using a self-signed certificate.
  • If the first attempt fails, it retries using a specified certificate.
  • Responses from the server are logged for debugging purposes.

Main Program

The main part of the script handles:

Command-Line Options

The script parses command-line options to enable verbose and debug logging:

while [[ $# -gt 0 ]]; do
  key="$1"
  case $key in
    -v | --verbose)
      verbose="true"
      shift
      ;;
    -d | --debug)
      debug="true"
      shift
      ;;
    *)
      shift
      ;;
  esac
done

Log Directory and File Setup

The script sets up paths for the log directory and file:

log_dir="$HOME/.bash_script"
log_file="$log_dir/cronjob_template_cron.log"

Monitoring Server URL and Certificate

It sets up the monitoring server URL and the certificate name:

monitoring_server_url="<insert_url>"
cert_name="<insert_cert.crt>"

Root Privileges Check

The script checks if it is being run with root privileges:

if [ "$EUID" -ne 0 ]; then
  log_message "ERROR: This script must be run as root or with sudo."
  exit 1
fi

Certificate File Path

It determines the path to the certificate file based on the operating system:

if [ -f /usr/local/share/ca-certificates/$cert_name ]; then
  cert_file="/usr/local/share/ca-certificates/$cert_name"
elif [ -f /etc/pki/ca-trust/source/anchors/$cert_name ]; then
  cert_file="/etc/pki/ca-trust/source/anchors/$cert_name"
else
  log_message "ERROR: Certificate file not found for this operating system."
  exit 1
fi

Log Directory and File Creation

It ensures the log directory and file exist, creating them if necessary:

if [ ! -d "$log_dir" ]; then
  mkdir -p "$log_dir"
fi

if [ ! -f "$log_file" ]; then
  touch "$log_file"
fi

Sending the Ping

Finally, the script sends a ping to the monitoring server and logs the result:

send_ping_to_monitor_server
log_message "INFO: Script execution completed successfully."

Conclusion

This script is a robust template for setting up a cron job that sends a system health check ping to a monitoring server. It includes detailed logging, error handling, and flexibility for different environments through command-line options and certificate management.

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Last updated 01 Sep 2024, 10:22 CEST . history