chronornd-job

README

chronornd-job

A command-line tool that executes specified commands at random times throughout the day, using a time-based queue implementation.

Overview

chronornd-job schedules and executes commands at random times during a 24-hour period. It maintains a sorted queue of jobs and fires each one at its scheduled time.

This makes it useful for:

• Random testing and monitoring
• Distributed task execution
• Load testing

Use with cron for daily scheduling:

# Schedule 5 random executions daily
0 0 * * * /usr/local/bin/chronornd-job -command="/path/to/script.sh" -n=5

# Schedule 5 random executions daily with serial execution
0 0 * * * /usr/local/bin/chronornd-job -command="/path/to/script.sh" -n=5 -serial

Installation

Build from source:

$ go build

Usage

Basic command format:

$ chronornd-job [OPTIONS] [-- COMMAND_ARGS]

Options

Option	Description	Default
-command	Command to execute	echo "Job executed at random time"
-n	Number of executions per day	10
-serial	Execute jobs serially (skip if previous job is running)	false

Examples

Run a backup script 5 times throughout the day:

$ chronornd-job -command="./backup.sh" -n=5

Execute rsync with arguments 3 times:

$ chronornd-job -command="rsync" -n=3 -- -av /src /dst

Execute shell commands with pipes:

$ chronornd-job -command="sh" -n=2 -- -c "date | tee /tmp/timestamp.log"

Run in serial mode (skip jobs if previous is still running):

$ chronornd-job -command="./long-running-task.sh" -n=5 -serial

Design

Features

• Random Scheduling: Jobs are scheduled at random times throughout the day
• Accurate Firing: Each job fires at its scheduled wall-clock time without drift, even if an earlier job is still running
• Serial Execution Mode: Optional mode to skip a job if the previous job is still running
• Signal Handling: Graceful shutdown on SIGINT and SIGTERM
• Command Arguments: Full support for command-line arguments and pipes

Job Queue Implementation

The program uses a simple queue-based design:

1. Generates the specified number of random execution times
2. Sorts them chronologically
3. Waits for each scheduled time and fires the job in the background, so firing never drifts behind a long-running job
4. In serial mode, skips a job if the previous job is still running

Logging

The program provides detailed logging of:

• Startup configuration
• Planned execution times
• Job execution status
• Error conditions
• Skipped jobs (when running in serial mode)

Example output (normal mode):

2024/11/25 10:00:00 Starting chronornd-job (Command: ./backup.sh, Executions: 5, Serial: false)
2024/11/25 10:00:00 Planned execution times:
2024/11/25 10:00:00   11:23:45
2024/11/25 10:00:00   14:15:30
2024/11/25 10:00:00   16:48:12

Example output (serial mode):

2024/11/25 10:00:00 Starting chronornd-job (Command: ./long-job.sh, Executions: 3, Serial: true)
2024/11/25 10:00:00 Planned execution times:
2024/11/25 10:00:00   11:00:00
2024/11/25 10:00:00   11:05:00
2024/11/25 10:00:00   11:10:00
2024/11/25 11:00:00 Executing command: ./long-job.sh
2024/11/25 11:05:00 Skipping job at 11:05:00: previous job is still running
2024/11/25 11:10:00 Skipping job at 11:10:00: previous job is still running

License

This project is licensed under the MIT License.