terraform-scheduled-scaling

Automatically stop dev/staging EC2 and RDS instances at night, start them in the morning. Save up to 65% on non-production AWS costs.

The Problem

Your dev and staging environments run 24/7 but are only used 10 hours a day, 5 days a week. That's 70% waste.

Without scheduling:  24h × 7d = 168 hours/week (paying for all)
With scheduling:     10h × 5d =  50 hours/week (paying for usage)
Savings:             70% reduction

How It Works

                    Lambda (Start)              Lambda (Stop)
                         │                           │
  8:30 AM IST ──► Start EC2 + RDS      8:00 PM IST ──► Stop EC2 + RDS
  (Mon-Fri)          instances          (Mon-Fri)         instances
                         │                           │
                    EventBridge                  EventBridge
                    Cron Schedule                Cron Schedule

Usage

module "scheduler" {
  source = "github.com/akshayghalme/terraform-scheduled-scaling"

  name = "dev-env"

  ec2_instance_ids = ["i-0abc123", "i-0def456"]
  rds_instance_ids = ["dev-database"]

  # Start at 8:30 AM IST (3:00 AM UTC) Mon-Fri
  start_cron = "0 3 ? * MON-FRI *"

  # Stop at 8:00 PM IST (2:30 PM UTC) Mon-Fri
  stop_cron = "30 14 ? * MON-FRI *"

  tags = { Environment = "dev" }
}

Common Schedules (UTC)

Work Hours (Local)	Timezone	start_cron	stop_cron
9 AM – 6 PM	IST (UTC+5:30)	30 3 ? * MON-FRI *	30 12 ? * MON-FRI *
9 AM – 6 PM	UTC	0 9 ? * MON-FRI *	0 18 ? * MON-FRI *
9 AM – 6 PM	EST (UTC-5)	0 14 ? * MON-FRI *	0 23 ? * MON-FRI *
9 AM – 6 PM	PST (UTC-8)	0 17 ? * MON-FRI *	0 2 ? * TUE-SAT *

Savings Examples

Resource	Monthly (24/7)	Monthly (scheduled)	Savings
t3.medium EC2	$30.40	$9.10	$21.30/mo
db.t3.medium RDS	$49.60	$14.90	$34.70/mo
3 EC2 + 1 RDS dev env	$140.80	$42.20	$98.60/mo
Annual (above)	$1,689	$507	$1,182/year

Inputs

Name	Description	Default
name	Name prefix	required
ec2_instance_ids	EC2 IDs to schedule	[]
rds_instance_ids	RDS identifiers to schedule	[]
start_cron	Start cron (UTC)	0 3 ? * MON-FRI *
stop_cron	Stop cron (UTC)	30 14 ? * MON-FRI *

Important Notes

• All cron times are in UTC
• RDS instances take 5-10 minutes to start/stop
• RDS auto-restarts after 7 days if stopped — this module handles re-stopping
• Tag your EC2 instances with ScheduledScaling = true

License

MIT

Author

Akshay Ghalme — akshayghalme.com