Terraform Provider CronMath

The CronMath provider allows you to perform time arithmetic operations on cron expressions within your Terraform configurations. It uses the cronmath library for cron expression manipulation.

Features

• ➕ Add minutes or hours to cron expressions
• ➖ Subtract minutes or hours from cron expressions
• 🔄 Handle day boundary transitions automatically
• 🌍 Perfect for timezone adjustments
• ⏰ Create staggered schedules easily

Requirements

• Terraform >= 1.0
• Go >= 1.21 (for development)

Installation

From Terraform Registry

terraform {
  required_providers {
    cronmath = {
      source  = "ryutaro-asada/cronmath"
      version = "~> 1.0"
    }
  }
}

provider "cronmath" {
  # No configuration required
}

Manual Installation

1. Download the latest release from the releases page
2. Extract the archive
3. Move the binary to ~/.terraform.d/plugins/registry.terraform.io/ryutaro-asada/cronmath/1.0.0/[OS]_[ARCH]/

Usage

Data Source: cronmath_calculate

Calculate a new cron expression by applying time operations:

data "cronmath_calculate" "morning_job" {
  input = "30 9 * * *"  # 9:30 AM
  
  operations {
    type  = "sub"
    value = 30
    unit  = "minutes"
  }
}

output "adjusted_schedule" {
  value = data.cronmath_calculate.morning_job.result  # "0 9 * * *"
}

Examples

Timezone Adjustment

# Convert UTC to EST (UTC-5)
data "cronmath_calculate" "est_schedule" {
  input = "0 15 * * *"  # 3:00 PM UTC
  
  operations {
    type  = "sub"
    value = 5
    unit  = "hours"
  }
}

# Convert UTC to JST (UTC+9)
data "cronmath_calculate" "jst_schedule" {
  input = "0 10 * * *"  # 10:00 AM UTC
  
  operations {
    type  = "add"
    value = 9
    unit  = "hours"
  }
}

Building the Provider

# Clone the repository
git clone https://github.com/ryutaro-asada/terraform-provider-cronmath.git
cd terraform-provider-cronmath

# Download dependencies
go mod download

# Build the provider
make build

# Install locally for testing
make install

Running Tests

# Run unit tests
make test

# Run acceptance tests
make testacc

# Run specific test
go test -v -run TestCronMathDataSource ./internal/provider/

License

This project is licensed under the Mozilla Public License 2.0 - see the LICENSE file for details.

Support

For bugs and feature requests, please open an issue.

Related Projects

• cronmath - The underlying library for cron expression manipulation
• Terraform Plugin Framework - Framework used to build this provider

Acknowledgments

• Built with Terraform Plugin Framework
• Cron expression manipulation powered by cronmath