Chr*nMaster

A modern, web-based interface for managing cron jobs.

Built with Next.js, TypeScript, and Tailwind CSS.

Features

• Modern UI: Beautiful, responsive interface with dark/light mode.
• System Information: Display hostname, IP address, uptime, memory, network and CPU info.
• Cron Job Management: View, create, and delete cron jobs with comments.
• Script management: View, create, and delete bash scripts on the go to use within your cron jobs.
• Docker Support: Runs entirely from a Docker container.
• Easy Setup: Quick presets for common cron schedules.

Quick Start

Using Docker (Recommended)

1. Create a docker-compose.yml file with this content:

services:
  cronjob-manager:
    image: ghcr.io/fccview/cronmaster:main
    container_name: cronmaster
    user: "root"
    network_mode: host
    pid: "host"
    environment:
      - NODE_ENV=production
      - DOCKER=true
      - NEXT_PUBLIC_CLOCK_UPDATE_INTERVAL=30000
      # Feel free to change port, as we're running this as host you won't be able to externally map it
      - PORT=40123
      # Enter the FULL relative path to the project directory where this docker-compose.yml file is located (use `pwd` to find it)
      - NEXT_PUBLIC_HOST_PROJECT_DIR=/path/to/cronmaster/directory
    volumes:
      # Mount the host's crontab for Linux/Unix systems
      - /var/spool/cron/crontabs:/host/cron/crontabs
      - /etc/crontab:/host/crontab:ro
      # Mount system information directories
      - /proc:/host/proc:ro
      - /sys:/host/sys:ro
      - /etc:/host/etc:ro
      - /usr:/host/usr:ro
      # Mount scripts directory for script execution
      - ./scripts:/app/scripts
      # Mount data directory for persistence
      - ./data:/app/data
      # Mount snippets directory for user-defined snippets
      - ./snippets:/app/snippets
    restart: unless-stopped
    security_opt:
      - no-new-privileges:true
    cap_add:
      - SYS_ADMIN
    init: true

2. Build and run with Docker Compose:

docker compose up --build

3. Open your browser and navigate to http://localhost:40123

Note: The Docker implementation uses direct file access to read and write crontab files, ensuring real-time synchronization with the host system's cron jobs. This approach bypasses the traditional crontab command limitations in containerized environments.

Local Development

1. Install dependencies:

yarn install

2. Run the development server:

yarn dev

3. Open your browser and navigate to http://localhost:3000

Environment Variables

The following environment variables can be configured:

Variable	Default	Description
NEXT_PUBLIC_CLOCK_UPDATE_INTERVAL	30000	Clock update interval in milliseconds (30 seconds)
NEXT_PUBLIC_HOST_PROJECT_DIR	N/A	Mandatory variable to make sure cron runs on the right path.

Example: To change the clock update interval to 60 seconds:

NEXT_PUBLIC_CLOCK_UPDATE_INTERVAL=60000 docker-compose up

Important Notes for Docker

• The container runs with network_mode: host and pid: "host" to access system information
• Root user is required for cron operations and direct file access
• System directories are mounted as read-only for security
• Crontab files are accessed directly via file system mounts at /host/cron/crontabs and /host/crontab for real-time reading and writing
• NEXT_PUBLIC_HOST_PROJECT_DIR is required in order for the scripts created within the app to run properly
• The DOCKER=true environment variable enables direct file access mode for crontab operations

Usage

Viewing System Information

The application automatically detects your operating system and displays:

• Platform (Linux/macOS/Windows - not supported)
• Hostname
• IP Address
• System Uptime
• Memory Usage
• CPU Information

Managing Cron Jobs

1. View Existing Jobs: All current cron jobs are displayed with their schedules and commands
2. Create New Jobs: Use the form on the right side to create new cron jobs
3. Quick Presets: Click on preset buttons for common schedules
4. Add Comments: Include descriptions for your cron jobs
5. Delete Jobs: Remove unwanted cron jobs with the delete button
6. Clone Jobs: Clone jobs to quickly edit the command in case it's similar

Cron Schedule Format

The application uses standard cron format: * * * * *

• First field: Minute (0-59)
• Second field: Hour (0-23)
• Third field: Day of month (1-31)
• Fourth field: Month (1-12)
• Fifth field: Day of week (0-7, where 0 and 7 are Sunday)

Managing Scripts

1. View Existing Scripts: All current user created scripts are displayed with their name and descriptions
2. Create New Script: Use the editor and snippets to quickly create scripts for your cron jobs.
3. Quick Snippets: Pre-set of snippets, with ability to add new ones. Check README.md in ./snippets
4. Delete Scripts: Remove unwanted scripts (this won't delete the cronjob, you will need to manually remove these yourself)
5. Clone Scripts: Clone scripts to quickly edit them in case they are similar to one another.

Technologies Used

• Next.js 14: React framework with App Router
• TypeScript: Type-safe JavaScript
• Tailwind CSS: Utility-first CSS framework
• Lucide React: Beautiful icons
• next-themes: Dark/light mode support
• Docker: Containerization

Security Considerations

• The application requires root access for cron operations
• System directories are mounted as read-only
• Input validation is implemented for all user inputs

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

License

This project is licensed under the MIT License.

Support

For issues and questions, please open an issue on the GitHub repository.