FlashCron

A lightning-fast, ultra-efficient cron daemon written in Rust

Schedule tasks at the speed of light

Features | Installation | Quick Start | Documentation | Contributing

Why FlashCron?

Traditional cron daemons get the job done, but they weren't built for speed. FlashCron is engineered from the ground up for blazing-fast performance:

Metric	FlashCron	Traditional cron	Improvement
Scheduler Init (1000 jobs)	~400 μs	10-50 ms	Up to 125x faster
Next Run Calculation	~500 ns	10-100 μs	Up to 200x faster
Memory Usage	2-5 MB	10-50 MB	Up to 90% less
Startup Time	<10 ms	50-200 ms	Up to 20x faster
CPU at Idle	<0.1%	0.5-2%	Up to 95% less

The Flash Philosophy

Priority Queue Scheduling: O(log n) operations, no polling loops
Zero-Copy Parsing: Minimal allocations in hot paths
Precise Sleep: CPU stays idle until the exact moment needed
Concurrent Execution: Configurable parallelism with async I/O
Optimized Binaries: LTO, stripped symbols, maximum optimization

Features

Core Functionality

Standard Cron Expressions: Full 5-field cron syntax support
TOML Configuration: Human-readable, version-control friendly
Hot Reload: Automatic config reload on file changes
Graceful Shutdown: Waits for running jobs to complete

Job Management

Timeout Handling: Kill runaway jobs automatically
Retry Support: Configurable retry count and delay
Environment Variables: Per-job environment injection
Working Directory: Per-job working directory
Concurrent Limits: Prevent resource exhaustion

Observability

Structured Logging: Human-readable or JSON format
Execution History: Track job success/failure rates
Prometheus Metrics: Optional metrics endpoint (feature flag)

Cross-Platform

Linux: Native support, systemd integration
macOS: Full support including Apple Silicon
Windows: Native Windows support

Installation

From Releases (Recommended)

Linux (x86_64)

curl -LO https://github.com/alfredo-baratta/flashcron/releases/latest/download/flashcron-linux-x86_64.tar.gz
tar xzf flashcron-linux-x86_64.tar.gz
sudo mv flashcron /usr/local/bin/

Linux (ARM64)

curl -LO https://github.com/alfredo-baratta/flashcron/releases/latest/download/flashcron-linux-aarch64.tar.gz
tar xzf flashcron-linux-aarch64.tar.gz
sudo mv flashcron /usr/local/bin/

macOS (Intel)

curl -LO https://github.com/alfredo-baratta/flashcron/releases/latest/download/flashcron-macos-x86_64.tar.gz
tar xzf flashcron-macos-x86_64.tar.gz
sudo mv flashcron /usr/local/bin/

macOS (Apple Silicon)

curl -LO https://github.com/alfredo-baratta/flashcron/releases/latest/download/flashcron-macos-aarch64.tar.gz
tar xzf flashcron-macos-aarch64.tar.gz
sudo mv flashcron /usr/local/bin/

Windows Download flashcron-windows-x86_64.zip from releases and extract to a directory in your PATH.

From Cargo

cargo install flashcron

From Source

git clone https://github.com/alfredo-baratta/flashcron
cd flashcron
cargo build --release

Docker

docker pull ghcr.io/alfredo-baratta/flashcron:latest

Quick Start

1. Generate Configuration

flashcron init -o flashcron.toml

2. Edit Configuration

[settings]
log_level = "info"
max_concurrent_jobs = 10

[jobs.backup]
schedule = "0 2 * * *"  # Daily at 2 AM
command = "/usr/local/bin/backup.sh"
description = "Daily backup"
timeout = 3600
retry_count = 3

[jobs.cleanup]
schedule = "0 */6 * * *"  # Every 6 hours
command = "find /tmp -mtime +7 -delete"
description = "Clean old temp files"
enabled = true

3. Validate Configuration

flashcron validate -c flashcron.toml

4. Start the Daemon

flashcron run -c flashcron.toml

CLI Reference

Command	Description
`flashcron run -c config.toml`	Start the daemon
`flashcron validate -c config.toml`	Validate configuration
`flashcron list -c config.toml`	List all jobs
`flashcron schedule -c config.toml`	Show upcoming runs
`flashcron trigger <job> -c config.toml`	Trigger job manually
`flashcron init -o config.toml`	Generate default config

Options

Option	Description
`-c, --config <PATH>`	Configuration file path
`-l, --log-level <LEVEL>`	Log level (trace, debug, info, warn, error)
`--json`	Output logs in JSON format
`--foreground`	Run in foreground (don't daemonize)

Configuration Reference

Global Settings

[settings]
log_level = "info"           # trace, debug, info, warn, error
json_logs = false            # JSON format for log aggregators
max_concurrent_jobs = 10     # 0 = unlimited
shell = "/bin/sh"            # Default shell
watch_config = true          # Hot reload on config changes
history_size = 1000          # Job execution history size
shutdown_grace_period = 30   # Seconds to wait on shutdown

Job Configuration

[jobs.example]
schedule = "*/5 * * * *"     # Cron expression (required)
command = "echo 'Hello'"     # Command to execute (required)
description = "Example job"  # Optional description
enabled = true               # Enable/disable job
working_dir = "/app"         # Working directory
environment = { KEY = "value" }  # Environment variables
timeout = 300                # Timeout in seconds (0 = none)
shell = "/bin/bash"          # Override default shell
retry_count = 3              # Retry on failure
retry_delay = 60             # Seconds between retries
max_output_size = 1048576    # Max stdout/stderr capture (bytes)
run_on_startup = false       # Run immediately on daemon start

Cron Expression Format

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (1-7, Sunday = 7)
│ │ │ │ │
* * * * *

Examples:

Expression	Description
`* * * * *`	Every minute
`/5 * * *`	Every 5 minutes
`0 * * * *`	Every hour
`0 0 * * *`	Daily at midnight
`0 2 * * *`	Daily at 2 AM
`0 0 * * 7`	Weekly on Sunday
`0 0 1 * *`	Monthly on the 1st
`0 9-17 * * 1-5`	Weekdays 9 AM - 5 PM hourly
`30 4 1,15 * *`	At 4:30 on 1st and 15th

Performance Benchmarks

Measured on AMD Ryzen 5 / Intel i7 equivalent:

Operation	Time	Notes
Cron expression parsing	1.8-4.9 μs	Depending on complexity
Next occurrence calculation	400-500 ns	Sub-microsecond
Scheduler init (10 jobs)	~10 μs	Instant startup
Scheduler init (100 jobs)	~50 μs	Scales linearly
Scheduler init (1000 jobs)	~400 μs	Still under 1ms
Config parsing (50 jobs)	~566 μs	TOML parsing included
Config parsing (200 jobs)	~2.9 ms	Large configs handled

Memory Profile

State	Memory
Idle (10 jobs)	~2 MB
Idle (100 jobs)	~3 MB
Running (10 concurrent)	~5 MB

Deployment

systemd Service

# /etc/systemd/system/flashcron.service
[Unit]
Description=FlashCron - Lightning-fast Cron Daemon
After=network.target

[Service]
Type=simple
User=flashcron
ExecStart=/usr/local/bin/flashcron run -c /etc/flashcron/config.toml
Restart=on-failure
RestartSec=5
Environment=RUST_LOG=info

[Install]
WantedBy=multi-user.target

sudo systemctl enable flashcron
sudo systemctl start flashcron

Docker Compose

version: '3.8'
services:
  flashcron:
    image: ghcr.io/alfredo-baratta/flashcron:latest
    volumes:
      - ./flashcron.toml:/app/config/flashcron.toml:ro
      - ./scripts:/scripts:ro
    restart: unless-stopped
    logging:
      driver: json-file
      options:
        max-size: "10m"
        max-file: "3"

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: flashcron
spec:
  replicas: 1
  selector:
    matchLabels:
      app: flashcron
  template:
    metadata:
      labels:
        app: flashcron
    spec:
      containers:
      - name: flashcron
        image: ghcr.io/alfredo-baratta/flashcron:latest
        resources:
          requests:
            memory: "8Mi"
            cpu: "10m"
          limits:
            memory: "32Mi"
            cpu: "100m"
        volumeMounts:
        - name: config
          mountPath: /app/config
      volumes:
      - name: config
        configMap:
          name: flashcron-config

Comparison with Alternatives

Feature	FlashCron	cron	fcron	systemd-timer
Memory usage	~2-5 MB	~1 MB	~5 MB	N/A (systemd)
Config format	TOML	crontab	fcrontab	unit files
Hot reload	Yes	No	Yes	Yes
Retry support	Yes	No	Yes	Yes
Timeout	Yes	No	Yes	Yes
Concurrent limit	Yes	No	No	No
Cross-platform	Yes	Unix	Unix	Linux
Metrics	Optional	No	No	journald
Performance	Optimized	Standard	Standard	Standard

Contributing

Contributions are welcome! See CONTRIBUTING.md for guidelines.

# Clone the repository
git clone https://github.com/alfredo-baratta/flashcron
cd flashcron

# Run tests
cargo test

# Run benchmarks
cargo bench

# Build release
cargo build --release

License

MIT License - see LICENSE for details.

Author

Alfredo Baratta - [email protected]

Acknowledgments

cron - Cron expression parsing
tokio - Async runtime
clap - CLI framework
tracing - Structured logging

Built for speed

Because every millisecond counts

Name		Name	Last commit message	Last commit date
Latest commit History 1 Commit
.github/workflows		.github/workflows
benches		benches
docs		docs
examples		examples
src		src
tests		tests
.gitignore		.gitignore
Cargo.toml		Cargo.toml
Dockerfile		Dockerfile
LICENSE		LICENSE
README.md		README.md

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FlashCron

Why FlashCron?

The Flash Philosophy

Features

Core Functionality

Job Management

Observability

Cross-Platform

Installation

From Releases (Recommended)

From Cargo

From Source

Docker

Quick Start

1. Generate Configuration

2. Edit Configuration

3. Validate Configuration

4. Start the Daemon

CLI Reference

Options

Configuration Reference

Global Settings

Job Configuration

Cron Expression Format

Performance Benchmarks

Memory Profile

Deployment

systemd Service

Docker Compose

Kubernetes

Comparison with Alternatives

Contributing

License

Author

Acknowledgments

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